Tổng hợp và khảo sát các tính chất của vật liệu nano phát quang nền NaYF4 chứa ion đất hiếm er3+ và yb3+ định hướng ứng dụng trong y sinh tt tiếng anh

s

MINISTRY OF EDUCATION
AND TRAINING

VIETNAM ACADEMY OF SCIENCE
AND TECHNOLOGY

GRADUATE UNIVERSITY SCIENCE AND TECHNOLOGY
-----------------------

Ha Thi Phuong

SYNTHESIS AND LUMINESCENT PROPERTIES
CHARACTERIZATION OF NANOMATERIALS BASED ON
NaYF4 MATRICES CONTAINING Er3+ AND Yb3+ FOR
BIOMEDICAL APPLICATION
Major: Optical, optoelectronic and photonic materials
Code: 9 44 01 27

SUMMARY OF DOCTORAL THESIS IN MATERIAL SCIENCE

Hanoi – 2019


The thesis has been completed at:
Institute of Materials Science - Vietnam Academy of Science
and Technology

Science supervisors:
1. Dr. Tran Thu Huong

2. Prof. Dr. Le Quoc Minh

Reviewer 1: Assoc. Prof. Dr. …..
Reviewer 2: Prof. Dr. …………
Reviewer 3: Assoc. ……………

The thesis was defended at Evaluation Council held at Graduate University of
Science and Technology - Vietnam Academy of Science and Technology on, 2019.

Thesis can be further referred at:
- The Library of Graduate University of Science and Technology.
- National Library of Vietnam.


1
INTRODUCTION

Nowadays, there are many applications of nanomaterials and products made of nanomaterials such as
material science, energy, environment, electronics and especially in biomedical sciences. In biomedical
science, luminescent nanomaterials could make flouorescent labelling possible and effective.
Notably, in the last few years, many types of nanomaterials have become the current subjects of basic
and applied research, such as nanomaterials containing rare-earth upconversion nanophosphors (UCNP).
When stimulating this materialby infrared light, radiant emission will be aborted in the visible region.
Therefore, they have become one of the new and recognized research objects in many sectors such as health
care, security, energy ....
When applying in the health care sector, the UCNP has two specific advantages compared to other
luminescent materials. First of all, using infrared stimulation sources minimizes the object's self-emitting
ability and enhances the contrast of micro-images. In addition, infrared light is safer for human body, which
does not cause cell changes, and it can penetrate a few millimeters into human tissue, which will make a
deeper intervention into the affected area.

There are many published works on UCNP types, in which oxide, fluoride base materials of ytri and
gadoli rare-earth ion-doped Er3+, Yb3+, Tm3+, Ho3+ are more prominent. Studies show that nanometer-sized
NaYF4 network will create upconversion luminescent effect with high, durable and luminescent performance
in different conditions. This material promises many potential applications bio security, optoelectronic and
especially in biomedical as image recognition (bioimaging), biological sensors (biosensing), therapy Cancer
(cancer therapy). Biological identification applications in vitro and in vivo of rare earth ionic doped UCNP
have high contrast ratio. Therefore, UCNP materials have great potential in designing and manufacturing
biological nano complexes. Very accurately identify some types of cancer cells.
In the world, some researchers’ groups collected UCNP materials in sizes ranging from a few tens to
several hundred nm, luminescent green areas, fingerprint recognition applications, drug guides, nanoscale oil
or they could be used in association with biomarkers that could test certain types of cells such as lung cancer
cells, Hela cells. In particular, many UCNP materials of several hundred nm can mark nm-sized cells by
extracellular method. Because the structure, luminescent properties and biological conjugation are some of
the determinants of biomedical application, the study of these factors has always played an important role in
material production.
Studies in Vietnam on luminescent nanomaterials containing rare soil. Although those research have
been just able to access nanotechnology, they have made important changes, creating new attraction for
scientists. For upconversion nanophosphors luminescent nanomaterials, several research groups have
investigated UCNPs containing Er, Yb, Tm ions, with oxides of ytri, sodiumytrifloride substrate. These
works mainly on the synthesis method, structure, size and shape as well as the characteristics and
mechanisms of fluorescence upconversion in a multi-photon form with the orientation of the application in
imaging, optoelectronics, security printing and some research results applied in the energy industry.
However, the problem of applying UCNP in cancer detection and treatment is not much. The question
is how to use upconversion nanophosphors into biomedical and choose which solution is suitable for the
process of functionalization, conjugation with biological activity objects. How does the combination of
nanotechnology and biology allow the application of nano-sized fluorescent materials for the purpose of
detecting and detecting biological molecules used in biomedical sensors and images?


2

For all the above mentioned points, I selected the topic of research on nanomaterials containing rare
earth upconverted luminescence application in medical biology as the content for the thesis with the title:
"Synthesis and luminescent properties characterization of nanomaterials based on NaYF4
matrices containing Er3+ and Yb3+ for biomedical application".
The goal of the thesis:
1. Successfully synthesized upconversion nanophosphors NaYF4: Yb3+, Er3+, hexagonal crystal
structure (β), rod shape, red light emission areas.
2. The morphology, structure and optical properties of NaYF4: Yb3+, Er3+ materials had investigated.
The process of covering, functionalizing, conjugating NaYF4 materials: Yb3+, Er3+ had constructing for
biomedical applications. From there, select the most appropriate material to fabricate the micro-image
fluorescent marker complex.
3. The experimental research and application of biomedical nano complexes of NaYF4: Yb3+, Er3+ @
silica-N = FA to identify breast cancer cells MCF7 through fluorescence immunity technique with reverse
fluorescence microscope
Research methods:
The thesis was conducted by experimental method.
1. The upconversion nanophosphors were synthesized by wet chemical methods (hydrothermal and
hydrothermal assisted soft template PEG) to make.
2. The structure and morphology of the sample was analyzed by modern measurements such as X-ray
diffraction pattern, infrared spectrometry, Field Emission Scanning Electron Microscopy. The luminescent
properties of studied samples were measured on high-resolution steady-state photoluminescent setups.
3. The application of biomedical nano complexes of NaYF4: Yb3+, Er3+ @ silica-N = FA were
investigated by fluorescence immunity technique.
i.

ii.

iii.

Novel contributions of thesis:

NaYF4: Yb3+, Er3+ upconversion nanophosphors with a hexagonal crystal structure (β) form were
successfully synthesized by hydrothermal method. The mean size of the NaYF4: Yb3+, Er3+
upconversion nanophosphors is about 100 nm ÷ 200 nm in diameter and 300 nm ÷ 800 nm in length.
Under an excitation wavelength of 980 nm, luminescence spectra consists of two characteristic emission
bands of Er3+ ion from 510 nm ÷ 570 nm and 630 nm ÷ 700 nm.
The biomedical nano complexes of NaYF4: Yb3+, Er3+ @ silica / TPGS and NaYF4: Yb3+, Er3+ @ silica
– N = FA were successfully synthesized. They have luminescent properties upconversion against
dominant red light emission areas.
The results of experimental research and application of biomedical nano complexes NaYF4: Yb3+, Er3+
@ silica-N = FA to identify breast cancer cells MCF7 through fluorescence immunity technique with

reverse fluorescence microscope shows that the pairing of nano complexes was observed with the cells.
Layout of thesis: The layout of the thesis: In addition to the introduction, conclusion, list of symbols
and abbreviations, list of tables, list of images and drawings, list of published works related to the thesis.
Project, appendices and references. Thesis content is presented in 4 chapters:
Chapter 1: Overview of upconversion nanophosphors containing rare earth ions in NaYF4 matricies
Chapter 2: Experimental techniques
Chapter 3: Presents the results of synthesis and investigate characterization of NaYF4: Yb3+, Er3+
upconversion nanophosphors.
Chapter 4: Presents the results of synthesis and Application of upconversion nanophosphors for
marking, identification of breast cancer cells MCF7


3
CHAPTER 1. OVERVIEW OF UPCONVERSION NANPPHOSPHORS CONTAINING RARE
EARTH IONS IN NAYF4 MATRICIES
1.1. Luminescent nanomaterials containing rare earth ions
1.1.1. General characteristics of rare earth elements
Common electron configurations of rare earth elements:
1s22s22p63s23p63d104s24p64d104fn5s25p65dm6s2 (n = 0 ÷ 14; m = 0 or 1).

The emission characteristic of rare earth ions is due to the presence of electrons inside the 4fn shell
(containing up to 14 electrons) that are not filled, as they are excited to high energy levels, lowering the energy
level down or down to the basics will result in luminescence.
1.1.2. Luminescent nanomaterials containing rare earth ions
Luminescent materials are coming from two main parts: substrate and doped material or luminescence
centers. Substrates are materials that have mechanical, structural stability and optical inertia.
1.1.2.1. Mechanism of luminescence containing rare earth ions
For rare-ion-doped luminescent materials, the luminescence mechanism of rare earth ions doped
basically is to shift the level of electrons in the atom. The luminescent mechanism of the material depends on
the electronic configuration of the rare-earth elements.
1.1.2.2. The separation of energy levels in 4f class of rare earth elements
Consider the influence of the Crystal field of the background. The 4f (not filled) electronic layer of
rare earth ions is covered by 2 layers of 5s25p6, so the effect of the surrounding crystal field is weak, so it is
possible to see the crystal field as a distortion. The key to this phenomenon is less dependent on the RE
background, but different backgrounds will have different levels of energy depending on the different
symmetries of the backgrounds.
1.1.2.3. The luminescence process of Lanthanide
For a fluorescence system based on Lanthanide, two major fluorescent processes occur: excitation
radiation is absorbed directly by the activator and absorbed radiation is absorbed by other ions or groups
of ions.
1.2. Upconversion luminescence process
1.2.1. Upconversion Mechanism of Lanthanide Upconversion Nanophosphors (UCNPs)
Most of these conventional materials exhibit luminescent emission with a Stokes shift (Scheme 1).
That is they emit lower-energy photons under excitation with higher-energy photons. A few processes have
been found to possess the ability to generate anti-Stokes photoluminescence. In these cases the emitted
photons have higher energy than those used for the excitation. Two-photon absorption-based luminescence
and secondharmonic generation are two kinds of anti-Stokes processes, which require coherent lasers as the
excitation sources and which have been well-investigated. Upconversion luminescence is a distinct antiStokes process. This process can be performed by low-power and incoherent excitation sources, such as
continuous-wave (CW) lasers, standard xenon or halogen lamps, or even focused sunlight. The general
principle of the upconversion luminescence process is illustrated in Scheme 1.4 which demonstrates the

difference to the conventional photoluminescence process.


4
The

mechanisms

of

lanthanide
upconversion
processes can be divided into
three main classes: excited-state
absorption,
energy-transfer
upconversion,
and
photon
avalanche.
Because
photon
avalanche is seldom found in
nanoscale lanthanide materials,
we will mainly discuss the
excited-state
absorption
and
energy-transfer
upconversion

processes.

Fig 1.4. Scheme 1. (a) Schematic Principle of Conventional
Photoluminescence and (b) the Upconversion Luminescence
Processes
1.2.2. UCNP composition Host, Activator, and Sensitizer for Lanthanide
UCNPs
1.2.2.1. Host lattice considerations
Selection of appropriate host materials is essential for high efficiency UC emissions. Basically, an
ideal host material should be transparent in the spectral range of interest, have high optical damage threshold,
and be chemically stable. Moreover the host lattice can affect the UC efficiency in two ways: (i) by the
phonon dynamics, and (ii) by the local crystal field.
Lanthanide UCNPs are generally comprised of an inorganic host and lanthanide dopant ions, although
some complexes showed upconversion luminescence in the literature. To date, the upconversion process has
been widely studied in various nanoscale host matrices, such as fluorides and other halides (chlorides,
bromides, and iodides), oxides, oxysulfides, phosphates, vanadates, among others. Ideal host materials
should have low lattice phonon energies so as to minimize nonradiative loss and maximize the radiative
emission. This is because nonradiative energy loss requires the assistance of phonons present in the host
lattice. Heavy halides, such as chlorides, bromides, and iodides generally exhibit low phonon energies of less
than 300 cm−1. However, they are hygroscopic and are of limited use. Oxides show high chemical stability,
but their phonon energies are relatively high, generally larger than 500 cm−1. In comparison, fluorides usually
exhibit low phonon energies (∼500 cm−1) and high chemical stability and thus are often used as host
materials for upconversion processes. To date, NaYF4 has been the most popular host for lanthanide UCNPs.
1.2.2.2. Activators
Since inorganic crystalline host materials do not partake in UC processes luminescent centers, referred
to as activators, are required. Most Ln3+ species can theoretically be used to produce UC emissions as they
have more than one excited 4f energy level (exceptions are La3+, Ce3+, Yb3+, and Lu3+). These Ln3+ species
offer long-lived metastable excited states (up to 0.1s, due to low f-f transition probabilities), as well as
multiple and equally spaced intermediate metastable energy levels in a ladder-like arrangement. This is
exemplified, using the activators of Er3+.

1.2.2.3. Sensitizers
Yb3+ has a larger absorption cross-section than those of the lanthanide activators. The 2F7/2 → 2F5/2
transition of Yb3+ is conveniently resonant with many f−f transitions of Er3+, Tm3+, and Ho3+, thus facilitating
efficient energy transfer from Yb3+ to these ions. Thus, Yb3+ is often codoped with Er3+, Tm3+, or Ho3+ as a
sensitizer to enhance upconversion emission. A CW 980 nm laser is applied as the excitation source to match
the 2F7/2 → 2F5/2 transition of Yb3+ (Scheme 3). Additionally, in this review, we concentrate on summarizing


5
the advances in Yb3+ sensitized UCNPs, although some transition-metal ions have also been reported to serve
as sensitizers or emitters to achieve upconversion emissions.
1.3. Several methods of synthesis luminescent nanomaterials contain rare earth ions for biomedical
applications
The chemical synthesis method controls the uniform size of the nanoparticle but usually produces only
very small amounts, suitable for applications in sophisticated technology, such as in nano electronics, nano
optics, and high-definition television, more recently in biomedical medicine. From different reaction
conditions, it is possible to synthesize nanomaterials with diverse shapes such as particles, rods, fibers, disks,
etc… One of those products is light-emitting nano materials containing rare earth ions such as Y2O3: Eu3+;
YVO4: Eu3+; NaYF4: Yb3+, Er3+ etc. In this thesis, we present three main chemical methods for synthesizing
luminescent nanomaterials containing rare earth ions for biomedical application: hydrothermal, sol-gel and
microwave.
1.4. Application of upconversion nanophosphors (UCNP) in biomedical engineering.
1.4.1. UCNP for Bioimaging
Luminescent imaging is very useful for early diagnosis and treatment of some incurable diseases. Over
the years, much research has been focused on developing new fluorescence imaging techniques and
luminescent labels in order to improve the signal-to-noise ratio (SNR). Due to the special CW-excited
upconversion process, upconversion emissive materials exhibit unique large anti-Stokes shifts. Thus,
upconversion luminescence imaging with UCNPs as labels could be expected to completely eliminate
autofluorescence from biotissues in bioimaging. To date, UCNPs have been successfully applied to the
bioimaging of various biological samples, including living cells and small animals. Because of the high

image contrast, in vitro and in vivo biological format applications of UCNP can be determined with high
accuracy, especially in in vitro conditions.
1.4.2. Lanthanide UCNP for biosensing
Optical sensing and assays play vital roles in theranostics due to the capability to detect hint
biochemical entities or molecular targets as well as to precisely monitor specific fundamental physiological
processes. UCNPs are promising for these endeavors due to the unique frequency converting capability of
biocompatible NIR light that is silent to tissues. They have the potential to reach a high detection sensitivity
deeply located in the living body systems. However, the PL of UCNPs is not directly related to any
biochemical property of a system except for temperature. Therefore, to be useful in a biochemical
recognition process (the fundamental process in chemical sensing), UCNPs have to be used in combination
with suitable recognition elements such as indicator dyes. The recognition element of a biosensor may
consist of an enzyme, an antibody, a polynucleotide, or even living cells. Next, the process of biochemical
recognition has to be transduced into an optical signal given by the UCNPs. The transduction was generally
implemented by a FRET and/or LRET mechanism. In the following, we summarized UCNP-based in vitro
temperature sensing, detection of ions (cyanide, mercury, etc.), sensing of small gas molecules (oxygen,
carbon dioxide, ammonia, etc.), as well as UCNP-based bioassays for biomolecules (avidin, ATP, DNA,
RNA, etc.).
1.4.3. Photothermal therapy (PTT)
Photothermal therapy (PTT) employs photoabsorbers to generate heat from light absorption, leading to
thermal ablation of cancer cells. In recent years, PTT has emerged as an increasingly recognized alternative
to classical cancer therapies such as surgery, radiotherapy, and chemotherapy. Various nanomaterials with
high optical absorbance have been highly successful in this application.


6
1.4.4. Photodynamic therapy (PDT)
Photodynamic therapy (PDT) is a clinical treatment that utilizes phototriggered chemical drugs
(photosensitizers) to produce singlet oxygen (1O2) to kill tumors. Typical PDT treatments involve three
components: the photosensitizer, the light source, and the oxygen within the tissue at the disease site. Under
appropriate light excitation (generally in the visible range), the photosensitizer can be excited from a ground

singlet state to an excited singlet state, which undergoes intersystem crossing to a longer-lived triplet state and
then reacts with a nearby oxygen molecule to produce highly cytotoxic 1O2. PDT has been used for therapy in
prostate, lung, head and neck, or skin cancers. However, conventional PDT is limited by the penetration depth
of visible light needed for its activation. NIR light in the “window of optical transparency” (750-1100 nm) of
tissue can penetrate significantly deeper into tissues than the visible light, because absorbance and light
scattering for most body constituents are minimal in this range. Importantly, UCNPs can efficiently convert the
deeply penetrating near-infrared light to visible wavelengths that can excite photosensitizer to produce
cytotoxic 1O, promising their use in PDT treatment of pertinent located deeply tumors.


7
CHAPTER 2. EXPERIMENTAL TECHNIQUES
2.1. Synthesis of NaYF4: Yb3+, Er3+ nanophosphors by hydrothermal method
NaYF4:Yb3+, Er3+ nanophosphors were prepared by hydrothermal method
2.2. The ways of the synthesis of NaYF4: Yb3+, Er3+ biomedical nanocomposite complexes
To make NaYF4: Yb3+, Er3+ biomedical nanocomposite complexes, it is necessary to first treat the
surface of the material, then the functionalization and conjugation of materials with biological agents.
2.2.1. Functionalization
Bio-compatible property of the UCNPs requires a core shell structure to protect the luminescent
materials and the cells involved. Besides that, the biolabels need to have specific property to target a specific
tumor such as its surface have to have proper ligands that bind to the cells.
2.2.2. Method of surface functionalization and conjugation between upconversion luminescent
nanomaterials and biological agents.
Surface silanization (or silica coating) is an inorganic surface treatment strategy to make nanoparticles
water-dispersible and biocompatible. Silica is known to be highly stable, biocompatible, and optically
transparent. When utilized as a coating material, surface silanization methods can flexibly offer abundant
functional groups (e.g., -COOH, -NH, -SH, etc.) and thus satisfy various needs of conjugation with
biological molecules (e.g., folic acid, peptides, proteins, DNA, succinimid, biotin etc.). There are two types
of related chemistry to coat silica onto the nanoparticles, depending on the polar nature of the capping
ligands on the particle surface. One is the Stober method, which can be utilized to coat silica on hydrophilic

UCNPs. Tetraethyl silicate (TEOS) is added to an excess of water containing a low molar-mass ethanol and
ammonia, together with the hydrophilic UCNPs. A precise control of the amounts of involved reagents as
well the pH value can lead to a uniform growth of silica onto the UCNPs.
2.3. The structure, morphology and luminescent properties of materials.
The morphological observation and crystalline phase identification of all prepared samples were
carried out by the way of using Field Emission Scanning Electron Microscopy (FESEM, Hitachi, S-4800),
(TEM, S-4800-HITACHI và JEOL-1010) and X-ray diffraction (XRD, Siemens. The luminescent properties
of studied samples were measured on high-resolution steady-state photoluminescent setup based on
luminescence spectrum photometer system, MicroSPEC-2356 với Laser He-Cd. FTIR were measured on
IMPACT-410, NICOLET. The microsized images of the specimens which from the virus infected cells
exposure with the conjugates from nanomaterials have been viewed by a fluorescent microscopic equipment
Olympus BX-40 (Japan).


8

CHAPTER 3. THE RESULTS OF SYNTHESIS AND INVESTIGATE
CHARACTERIZATION OF NAYF4: Yb3+, Er3+ UPCONVERSION NANPPHOSPHORS
3.1. The synthesis of NaYF4: Yb3+, Er3+ upconversion nanophosphors
3.1.1. Synthesis process of NaYF4: Yb3+, Er3+ upconversion nanophosphors (Process 1)
Synthesis process of nano materials containing rare earth ions NaYF4: Yb3+, Er3+ (process 1) by
hydrothermal method is shown in Figure 3.1.

Solution NaOH
(200; 4000; 6000; 20000)
Solution A

C2H5OH + PEG

Stir / 30 minutes

Y3+ : Yb3+: Er3+
(79,5: 20,0: 0,5)

Solution B
Stir / 120 minutes

Solution C

Solution NaF

190 oC/ 24 hours

Solution D
Centrifuge, wash, dry

Powder NaYF4: Yb3+, Er3+
Fig 3.1. Synthesis process of nano materials containing rare earth ions NaYF4:Yb3+, Er3 (process 1)
NaYF4: Yb3+, Er3+ samples were synthesized according to process 1 and listed in Table 3.1.
Table 3.1. The list of NaYF4: Yb3+, Er3+samples were synthesized according to process 1.
No.
1
2
3
4

Samples
M1
M2
M3

M4

Y3+ (% mol)
79,00
79,25
79,50
79,75

Yb3+ (% mol)
20,50
20,25
20,00
19,75

Er3+ (% mol)
0,5
0,5
0,5
0,5

3.1.2. The results of Investigate of the structure and morphology of NaYF4: Yb3+, Er3+ upconversion
nanophosphors according to process 1.
3.1.2.1. XRD pattern of the nanophosphors of NaYF4: Yb3+, Er3+ were synthesized according to process1.
XRD pattern of the nanophosphors of NaYF4: Yb3+, Er3+ at 190 oC, 24 hours with different Yb3+/Y3+
ratios : M1 (20,5/79) - line 1; M2 (20,25/79,25) - line 2; M3 (20/79,5) - line 3 and M4 (19,75/79,75) - line 4
were synthesized according to procedure 1 presented in Figure 3.2 .


9
The phase structures of NaYF4:Yb3+,

(1) M1
(2) M2
(3) M3
(4) M4
Cubic NaYF4

Intensity (a.u)

Er3+ nanophosphors were investigated by
X-ray diffraction (XRD) and the results are
showed in Fig. 3.2. In the XRD pattern of
the sample, there are diffraction peaks at
2: 29.5o; 30.8o; 34.7o; 39.5o; 43.5o;
53.2o; 59.8o; 61.2o; 62.2o; 68.3o; 71o;
78.95o equal to hexagonal phase of NaYF4

Hex NaYF4
(4)
(3)
(2)
(1)

(JCPDS card No. 28-1192); at 2: 28,3 o;
32,8 o; 46,9 o; 55,7 o; 58,4 ; 75,7o, 78,06 o
20

40

60

and 87,50 o. equal to hexagonal phase of
2- Theta (degree)
NaYF4 (JCPDS card No. 77-2042 of α – Fig 3.2. XRD pattern of the nanophosphors of NaYF4: Yb3+, Er3+ at
NaYF4 (cubic). We found that all measured
190 oC, 24 hours with different Yb3+/Y3+ ratios: M1 (20,5/79); M2
peaks are belonging to this standard
(20,25/79,25); M3 (20/79,5) và M4 (19,75/79,75)
pattern.
3.1.2.2. The morphology of NaYF4: Yb3+, Er3+ were synthesized according to process 1
FESEM images of the nanophosphors of NaYF4: Yb3+, Er3+ with different Yb3+/Y3+ ratios 20,5/79
(M1); 20,25/ 79,25 (M2); 20,0/79,5 (M3); 19,75/ 79,75 (M4) were presented in Figure 3. 3. The results
showed that all samples were in the form of square blocks with dimensions of about 100 nm 300 nm.

M1

M2

M3

M4

Fig. 3.3. FESEM images of the nanophosphors of NaYF4: Yb3+, Er3+ with different Yb3+/Y3+ ratios 20,5/79
(M1); 20,25/ 79,25 (M2); 20,0/79,5 (M3); 19,75/ 79,75 (M4)
3.1.2.3. The upconversion luminescence (UCL) spectra of NaYF4: Yb3+, Er3+ were synthesized according to
process 1.
Combining morphological and structural studies, we continue to investigate the luminescent properties
of NaYF4: Yb3+, Er3+ samples through upconversion luminescence (UCL) spectra.


10

The

results

of

The

15/2

4
- I

4

4
- I
S
15/2
3/2

11/2

H

2

Indensity (a.u)

4

4
- I
F
15/2
9/2

M1
upconversion
luminescence
M2
(UCL) spectra analysis in Figure
M3
M4
3.4 show that when excited at
980 nm, all samples have a
M3
fluorescence effect that converts
M4
in reverse with blue at
wavelengths (510 nm ÷ 570 nm)
M2
and red at wavelengths (630 nm
÷ 700 nm) corresponding to
2
H11/2 → 4I15/2; 4S3/2 → 4I15/2 and
M1
4
F9/2 → 4I15/2 of Er3+ ions. Thus,
from the results of the
500

550
600
650
700
750
upconversion
luminescence
Wavelength (nm)
(UCL) spectra, the red zone
Fig 3.4. The upconversion luminescence (UCL) spectra of the
emission of the M3 sample
3+
3+
nanophosphors of NaYF4: Yb3+, Er3+ with different Yb3+/Y3+ ratios:
(NaYF4: Yb , Er with molar
ratio Yb3+ / Y3+ = 20.0 / 79.5 is 20,5/79 (M1); 20,25/ 79,25 (M2); 20,0/79,5 (M3) and 19,75/ 79,75 (M4)
under NIR laser excitation at 980 nm
dominant).
Schematic diagram of energy, radiation and non-radiation processes of Yb3+/ Er3+codoped materials
were shown in Figure 3.5.

Fig. 3.5. Schematic diagram of energy, radiation and non-radiation processes of
Yb3+/Er3+codoped materials
3.2. The synthesis of NaYF4: Yb3+, Er3+ upconversion nanophosphors assisted soft template PEG
3.2.1. Synthesis process of NaYF4: Yb3+, Er3+ upconversion nanophosphors assisted soft template PEG
Synthesis process of NaYF4: Yb3+, Er3+ upconversion nanophosphors assisted soft template PEG is
shown in Figure 3.7.


11

Solution NaOH
(200; 4000; 6000; 20000)
Solution A

C2H5OH + PEG

Stir / 30 minutes

Y3+ :

Yb3+:

Er3+

Solution B

(79,5: 20,0: 0,5)

Stir / 120 minutes

Solution C

Solution NaF

190 oC/ 24 hours

Solution D
Centrifuge, wash, dry

Powder NaYF4: Yb3+, Er3+
Fig 3.7. Synthesis process of NaYF4: Yb3+, Er3+nanomaterials assisted soft template PEG
NaYF4: Yb3+, Er3+ - PEG samples were synthesized according to process 1 and listed in Table 3.4.
Table 3.4. The list of NaYF4: Yb3+, Er3+ (Y3+/ Yb3+/ Er3+ = 79,5/ 20/ 0,5)
with PEG =200; 4000; 6000; 20000 were synthesized according to procedure 1.
No.

Sample

%
Y

1

M3

3+

%
3+

Yb

%
Er

3+

MPE
G

79,5

20

0,5

79,5

20

0,5

200

79,5

20

0,5

400

0
2
MP2

0

3

MP4

0

4

0
79,5

MP6

0,5

0

5

600
0

79,5
MP20

20
20

0,5

0

200
00

3+

3+

3.2.2. The results of Investigate of the structure and morphology of NaYF4: Yb , Er - PEG
3.2.2.1. XRD pattern of the nanophosphors of NaYF4: Yb3+, Er3+ - PEG


12
(1) M3
(2) MP2
(3) MP4
(4) MP6
(5) MP20
Cubic-NaYF4

Intensity (a.u)

Hexa-NaYF4

(5)
(4)
(3)
(2)
(1)

30

40

50

60

70

2-Theta (degree)

Fig 3.8. XRD pattern of the nanophosphors of NaYF4: Yb3+, Er3+ at 190 oC, 24 hours (M1 - line 1) ,
NaYF4:Yb3+, Er3+ - PEG 200 (MP2 - line 2); PEG 4000 (MP4 - line 3); PEG 6000 (MP6 - line 4);
PEG 20000 (MP20 - line 5)
3+
3+
NaYF4: Yb , Er assisted soft template PEG with NaYF4: Yb3+, Er3+ at 190 oC, 24 hours (M1 - line
1), NaYF4:Yb3+, Er3+ - PEG 200 (MP2 - line 2); PEG 4000 (MP4 - line 3); PEG 6000 (MP6 - line 4); PEG
20000 (MP20 - line 5) are showed in Fig. 3.8. The analysis results on the X-ray diffraction diagram in Figure
3.10 show the phase structure of M3 (line 1), MP2 (line 2), MP4 (line 3), MP6 (line 4) and MP20 (line 5)
models. ) still has a two-phase mixed structure α, -NaYF4. The diffraction peaks on the diagram are all
sharp to show that the samples are crystallized. This proves that the presence of PEG in the sample does not
change the phase structure of the material.
3.2.2.2. FESEM images of the nanophosphors of NaYF4: Yb3+, Er3+ - PEG
After investigating the structure of the material, we continue to investigate the effect of PEG on the
morphology of NaYF4 materials: Yb3+, Er3+ (Figures 3.11 and 3.12).

(a)

(b)

Fig 3.9. FESEM images of the nanophosphors of NaYF4: Yb3+, Er3+ - PEG 200 (a) and PEG 4000 (b)
FESEM image in Figure 3.9 of the MP2, MP4 samples and Figure 3.10 of the MP6 and MP20 samples
show that the samples are still in the square shape with the size of about 100 nm ÷ 300 nm. This proves that
the presence of soft-forming agent PEG does not change the morphology of the material.


13

(a)

Fig. 3.10. FESEM images of the nanophosphors of NaYF4: Yb3+, Er3+ - PEG 6000 (a) and PEG 20000 (b)
3.2.3. The luminescent properties of the nanophosphors of NaYF4: Yb3+, Er3+ - PEG
Under NIR laser excitation at 980 nm, the upconversion luminescence (UCL) spectra of NaYF4: Yb3+,
Er3+ - PEG were shown in Figure 3.11. Observing the spectra on the samples MP2, MP4, MP6, MP20 all
appear emission peaks in the region with wavelength from 400  700 nm. The emission peaks wavelength
range from 510  570 nm and from 630  700 nm, corresponding to 2H11/2 → 4I15/2; (520nm), 4S3/2 → 4I15/2

4
- I
15/2

(540nm) and 4F9/2 → 4I15/2 (650nm) of Er3+ ions.
λexc = 980 nm

(1) MP2

9/2

(2) MP4

4
F

(3) MP6

4
- I
15/2
4
S

3/2

2

Intensity (a.u)

H11/2 - 4I15/2

(4) MP20

(4)
(3)

500

550

600

650

700

(1)

(2)

750

Wavelength (nm)

Fig 3.11. The upconversion luminescence (UCL) spectra of the nanophosphors of NaYF4: Yb3+,
Er3+- PEG 200 (MP2 - line 1); PEG 4000 (MP4 - line 2); PEG 6000 (MP6 - line 3) and PEG
20000 (MP20 - line 4) under NIR laser excitation at 980 nm.
Observing the emission peaks between the red and blue regions shows that the red zone emission is
more dominant, especially the emission intensity of NaYF4:Yb3+, Er3+ - PEG 20000 emitting red is much
higher than intensity NaYF4: Yb3+, Er3+ - PEG nanomaterial emissions have low molecular weight under
NIR laser excitation at 980 nm.
The β-NaYF4 hexagonal structure material has the ability to luminesce reverse conversion about 10
times larger than the -NaYF4 form. In order to synthesize materials with hexagonal structure β-NaYF4, a
number of factors can be changed such as reaction time, annealing temperature, concentration of sensitizers,
luminescent center concentration, pH, etc. In the thesis, in order to synthesize materials with the desired β-


14
NaYF4 hexagonal structure, we have changed the order of creating NaYF4 matrices in the process of material
synthesis.
3.3. The synthesis of NaYF4: Yb3+, Er3+ upconversion nanophosphors with NaYF4 matrices order

change.
3.3.1. Synthesis process of NaYF4: Yb3+, Er3+ upconversion nanophosphors with NaYF4 matrices order
change (process 2)
Table 3.5. The list of NaYF4: Yb3+, Er3+samples were synthesized according to process 2
No.

Samples

% Y3+

% Yb3+

% Er3+

MPEG

1

EY1

79,75

20,0

0,25

20.000

2

EY2

79,50

20,0

0,50

20.000

3

EY3

79,00

20,0

1,00

20.000

4

EY4

78,00

20,0

2,00

20.000

NaYF4: Yb3+, Er3+ - PEG 20000 samples were synthesized according to process 2 (Fig 3.13) was listed
in Table 3.5
SolutionNaOH

Solution A

C2H5OH + PEG
Y3+ + NaF

Stir / 30 minutes

RE3+

Solution
(Yb3+ + Er3+)

Solution B
Stir / 120 minutes

Solution C
190 oC/ 24 hours

SolutionD
Centrifuge, wash, dry

Powder

NaYF4: Yb3+, Er3+

Fig 3.13. Synthesis process of nanomaterials containing rare earth ions NaYF4: Yb3+, Er3+ with
NaYF4 matrices order change (Process 2)
3.3.2. The result of Investigate of the structure and morphology of NaYF4: Yb3+, Er3+ upconversion
luminescent nanomaterials according to process 2
3.3.2.1. XRD pattern of the nanophosphors of NaYF4: Yb3+, Er3+ were synthesized according to process 2.


15
The results of XRD diagram
EY2
Hexagonal NaYF4

analysis of EY2 sample presented in
Figure 3.14 show at the 2 angles: 17,1 
53,2 ; 55,3 ; 62,3 ; 71,03 ; 86,7 .
There are diffraction peaks equivalent to
the -NaYF4 hexagonal. The XRD
schema results of the EY2 model match
the results on the JCPDS standard card
number 00-028-1192. In addition to the

Intensity (a.u)

; 29,9 ; 30,8 ; 34,7 ; 43,5 ; 46,5 ;

diffraction peaks of the  -NaYF4 phase,

JCPDS No.28-1192

on the XDR diagram of the sample, no
strange peaks were observed. This shows
that NaYF4:Yb3+, Er3+ samples with
PEG 20000 were synthesized according
to the structured procedure 2 with the

30

40

50

60

70

2 - Theta (degree)

-NaYF4 hexagonal phase structure,
indicating that the molar ratio of
Er3+/ Y3+ did not affect the structure
crystal of material.

Intensity (a.u)

Fig 3.14. XRD pattern of the nanophosphors of NaYF4:Yb3+, Er3+ PEG20000 (EY2) at 190 oC, 24 hours synthesized according to
desired -NaYF4 phase structure.
process 2
3+

We continue to investigate the effect of the molar ratio of Er / Y3+ on the crystal structure of the
synthesized samples according to process 2 (Fig 3.15).
The results showed that, with
(1) EY1
(2) EY2
the change of the molar ratio of
(3) EY3
(4) EY4
Er3+/ Y3+, the samples still showed
Hex NaYF4
diffraction peaks equivalent to the

(4)
(3)
(2)
(1)

20

40

60

2 - Theta (degree)

Fig . 3.15: XRD pattern of the nanophosphors of NaYF4:Yb3+, Er3+ PEG20000 (EY2) at 190 oC, 24 hours with change of Er3+/ Y3+ ratio
synthesized according to process 2 ( EY1 = 0,25/ 79,75; EY2 = 0,5/ 79,5;
EY3 = 1,0/ 79,0; EY4 =2,0/ 78,0)
Thus, changing the matricies order in the synthesis process obtained NaYF4: Yb3+, Er3+ materials with
desired hexagonal structure  -NaYF4.

3.3.2.2. The morphology of NaYF4: Yb3+, Er3+ has the structure of β-NaYF4
FE-SEM images of the nanophosphors were presented in Figure 3.17. The FE-SEM image of the
NaYF4:Yb3+, Er3+ indicates that the nanorods have bundles shape with the lengths of rod about 300  800 nm
and diameter of rod about 100  200 nm.


16

(a)

(b)

(c)
(d)
Fig. 3.17. FESEM images of the nanophosphors of EY1 (a), EY2 (b) , EY3 (c) và EY4 (d) with β-NaYF4
(synthesized according to process 2)
3.3.3. Luminescent properties of NaYF4:Yb3+, Er3+ has the structure of β-NaYF4
Luminescent properties of
(1) EY1- 0,25% Er
NaYF4:Yb3+, Er3+-PEG has the
(2) EY2 - 0,5% Er
(3) EY3 - 1,0% Er
structure of β-NaYF4 with change
(4) EY4 - 2,0% Er
of
Er3+/ Y3+ ratio were
investigated. Fig.3.18 shows the
(4)
upconversion
luminescence

(UCL) spectra of the samples
(3)
EY1, EY2, EY3 and EY4. The
results showed that the samples
(2)
emitted blue and red areas
corresponding to the transitions of
(1)
Er3+, the red emission rate of EY2
450
500
550
600
650
700
750
was strongest (EY2 compared to
Wavelength (nm)
EY1 is 1.53 times; compared to
Fig 3.18. The upconversion luminescence (UCL) spectra of the
EY3 is 4.58 times).
nanophosphors of NaYF4:Yb3+, Er3+ with change of Er3+/ Y3+ ratio
synthesized according to process 2, under NIR laser excitation at 980 nm
F9/2- 4I15/2

3+

3+

4

3+

S3/2- 4I15/2
4

H11/2- 4I15/2
2

Intensity (a.u)

3+


17

CHAPTER 4. THE RESULT OF SYNTHESIS AND APPLICATION OF UPCONVERSION
NANPPHOSPHORS CONTAINING RARE EARTH IONS FOR MARKING,
IDENTIFICATION BREAST CANCER CELLS MCF7
4.1. Surface treatment, functionalization and conjugation of NaYF4 materials containing Yb3+ and
Er3+ ions
4.1.1. Surface treatment of NaYF4 material containing Yb3+ and Er3+ ions with silica
TEOS + C2H5OH

(TEOS: TetraEthylOcthorSilicate)

Stir / 15 minutes

Solution A

CH3COOH + H2O

Stir /30 minutes

Solution B

NaYF4: Yb3+, Er3+@NaYF4
+ C2H5OH

Stir / 6 hours

Solution
NaYF4:Yb3+, Er3+

@NaYF4 @silica

Centrifuge,
wash, dry

NaYF4:

Powder
Er3+@NaYF4@silica

Yb3+,

Fig.4.1. Surface treatment process of NaYF4:Yb3+, Er3+ with silica
4.1.2. Functionalization of NaYF4: Yb3+, Er3+@silica with APTMS
APTMS +
C2H5OH

NaYF4: Yb3+, Er3+@NaYF4@silica
+ C2H5OH + H2O
Stir/ 20 minutes

Stir/ 20 minutes
Hydrolysis

Solution 1

Solution 2
APTMS
(3-aminopropyltrimethoxysilane)

Silanol condensation

Stir / 12 hours

Mixture
Centrifuge,
wash

NaYF4: Yb3+, Er3+@NaYF4@silica-NH2

NaYF4: Yb3+, Er3+@NaYF4@silica-NH2
NaYF4: Yb3+, Er3+@NaYF4@silica

Fig. 4.2. Functionalization process of
NaYF4: Yb3+, Er3+@silica with APTMS

Fig. 4.3. Reaction phases of NH2 group on NaYF4: Yb3+,
Er3+@silica with APTMS


18
4.1.3. Functionalization of NaYF4:Yb3+, Er3+@silica with TPGS
NaYF4: Yb3+, Er3+@NaYF4@silica
+ TPGS + cyclohexan
Sir / 30 minutes

Stir / 1 hour
Solution A

DCC + NHS

FA + DMSO

VLPQ @silica-NH2
+ ET

H2O

Stir / 1 hour, 70 oC

Stir / 30 minutes

Solution 1

Stir / 4 hours

Stir / 30 minutes

Solution
NaYF4: Yb3+, Er3+
@NaYF4@silica
@TPGS

Solution 4

Solution 3
ET: ethanol
FA: folic acid
VLPQ: NaYF4: Yb3+, Er3+
DMSO: dimethyl sulfoxide
NHS: N-Hydroxysuccinimide
DCC: N, N’-Dicyclohexylcarbodiimide
PBS: Phosphate Buffer Saline

Centrifuge, wash
Powder
NaYF4: Yb3+, Er3+
@NaYF4@silica
/TPGS

Solution 2

Stir / 20 hours

Centrifuge, wash (PBS)

NaYF4: Yb3+, Er3+ @silica-N=FA

Fig. 4.7: Conjugation process of NaYF4:Yb3+, Er3+@silica-NH2
material with folic acid

Fig. 4.5. Functionalization process of
NaYF4:Yb3+, Er3+@silica with TPGS

4.1.4. Conjugation of NaYF4: Yb3+, Er3+@silica-NH2 materials with folic acid
Fig. 4.7 discribed conjugation process of NaYF4:Yb3+, Er3+@silica-NH2 material with folic acid. Complex
reaction NaYF4:Yb3+, Er3+@ silica-N = FAbiomedical nanoparticles reaction is shown in Figure 4.8.

R – NH2

NHS + DCC

Carboxylic Acid

Amide

NHS ester

(NaYF4:Yb3+, Er3+ @silica-N=FA)

NHS: N-Hydroxysuccinimide
(C4H5NO3)

DCC: N, N’-Dicyclohexylcarbodiimide
(C13H22N2)

Figure 4.8. Reaction to form NaYF4:Yb3+, Er3+@ silica-N=FA biomedical nanoparticles
The teste to investigate the ability to pair of NaYF4:Yb3+, Er3+@silica-N=FA biomedical nanoparticles
with mark MCF7 breast cancer cell (Fig. 4.9).


19

Fig. 4.9. Biological conjugation process of NaYF4:Yb3+, Er3+ @ silica-N = FA with MCF7 cancer cells
4.2. The results of morphology, structure and luminescent properties of functionalized and conjugated
materials
4.2.1. The morphology, structure and luminescent properties of functionalized and conjugated of
NaYF4:Yb3+, Er3+@silica

(a)

(b)

Fig 4.10. FESEM images of the nanophosphors of NaYF4:Yb3+, Er3+(a) và NaYF4:Yb3+, Er3+@ silica (b)
at 190 oC, 24 hours
FESEM image results show that, with samples NaYF4:Yb3+, Er3+ uncoated silica (Figure 4.10a) the
rod-shaped material, the length is about 300 nm ÷ 800nm and the diameter of 100 nm ÷ 200nm and is not
sticky. With the presence of silica, samples NaYF4:Yb3+, Er3+ @ silica (Figure 4.10b), the morphology of the
material is still in the form of rods with increasing but not significant size.
Morphology of NaYF4:Yb3+, Er3+@ silica after functionalization, conjugation by attaching -NH2 group
with APTMS, TPGS and FA attachment were observed on field electron microscopes and were shown in
Figure 4.11. Looking at FESEM image shows the presence of TPGS in Figure 4.11a (NaYF4:Yb3+, Er3+@
silica / TPGS), of -NH2 in Figure 4.11b (NaYF4:Yb3+, Er3+@ silica-NH2) and FA in Figure 4.11c
(NaYF4:Yb3+, Er3+@ silica-N = FA) shows that the material is still rod-shaped with a length of about 300nm

20
÷ 800nm and a diameter of about 200 ÷ 300 nm. Thus, the materials NaYF4:Yb3+, Er3+ after being covered
with silica and attached with the TPGS or -NH2 or FA groups are not morphologically changed.

(a)

(b)

(c)

Fig 4.11. FESEM images of the nanophosphors of NaYF4: Yb3+, Er3+@ silica-TPGS (a), NaYF4: Yb3+,
Er3+@silica-NH2 (b) and NaYF4: Yb3+, Er3+@silica-N=FA (c) at 190 oC, 24 hours
4.2.2. Fourier transform infrared spectrum of NaYF4:Yb3+, Er3+@ silica were functionalized, conjugated.

776

573

1060

3+
3+
(2) NaYF4:Yb , Er @silica

3646

3430

Transmittance (%)

2070

1640

3+
3+
(3) NaYF4:Yb , Er @silica/TPGS

1010

3+
3+
(1) NaYF4:Yb , Er

4000

3000

2000

1000

-1

Wavenumber (cm )

Fig 4.12. FTIR spectra of the nanophosphors of NaYF4: Yb3+, Er3+ (1), NaYF4: Yb3+, Er3+@silica
(2) and NaYF4: Yb3+, Er3+@silica/TPGS (3)
Fig 4.12. presented FTIR spectra of the nanophosphors of NaYF4: Yb3+, Er3+ (line 1), NaYF4: Yb3+,
Er3+ @ silica (line 2) and NaYF4: Yb3+, Er3+ @ silica / TPGS (line 3) recorded in the region of 4000 cm-1 ÷

400 cm-1. Infrared spectroscopy survey of samples showed that TPGS has improved the dispersion ability of
domestic materials as well as in some other biological buffer solutions. This is also consistent with a number
of published studies. From the above results, we believe that TPGS has been successfully attached to
NaYF4:Yb3+, Er3+ silica.
Similarly, for materials NaYF4: Yb3+, Er3+ conjugated by FA, infrared spectrum of NaYF4:Yb3+, Er3+
(line 1); NaYF4:Yb3+, Er3+ @ silica (line 2); NaYF4:Yb3+, Er3+@ silica-NH2 (line 3) and NaYF4:Yb3+, Er3+@
silica-N = FA (line 4) were also surveyed and shown in Figure 4.13.


1008
950

1420
1312

(3)

1090

780

Transmittance (%)

3440

1650

(4)

2070

21

(2)

(1)

549

3+
3+
(1) NaYF4:Yb , Er

3643

3+
3+
(2) NaYF4:Yb , Er @silica
3+
3+
(3) NaYF4:Yb , Er @silica-NH

2

3+
3+
(4) NaYF4:Yb , Er @silica-N=FA

4000

3000

2000

1000

-1

Wavenumber (cm )

Fig 4.13. FTIR spectra of the nanophosphors of NaYF4: Yb3+, Er3+ (1); NaYF4: Yb3+, Er3+@silica (2);
NaYF4: Yb3+, Er3+@silica-NH2 (3) and NaYF4: Yb3+, Er3+@silica-N=FA (4)
Observing the infrared spectrum of the samples showed that chemical bonds between FA molecules
and inorganic components were formed. These results demonstrate that FA ligands have been successfully
paired to NaYF4: Yb3+, Er3+@slica-NH2.
4.2.3. Luminescent properties of NaYF4:Yb3+, Er3+@silica material: Yb3+, Er3+ @ silica have functionalized
and conjugated.

4
4
F9/2 - I15/2

(1) NaYF4:Yb3+, Er3+

Intensity (a.u)

(2) NaYF4:Yb3+, Er3+@Silica

4
4S

3/2 - I15/2

(a)

2

H

11/2

4
- I

15/2

(2)

500

550

600

650

700

750

Wavelength (nm)

Fig 4. 14. The upconversion luminescence (UCL) spectra of the nanophosphors of NaYF4:
Yb3+, Er3+(1); NaYF4: Yb3+, Er3+@silica (2) under NIR laser excitation at 980 nm
Figure 4. 14 shows the upconversion luminescence (UCL) spectra of the nanophosphors of NaYF4:
Yb3+, Er3+(1); NaYF4: Yb3+, Er3+@silica (2) under NIR laser excitation at 980 nm. The results showed that
when coved in silica, the intensity of fluorescence increased 2.5 times. After covering the silica, we
functionalized them with TPGS and APTMS.


22
3+

3+

2

4

H11/2 - I15/2

Intensity (a.u)

4
4
S3/2 - I15/2

4
4
F11/2 - I15/2

NaYF4: Yb , Er @silica/TPGS

500

550

600

650

700

Wavelength (nm)

Fig 4.15. The upconversion luminescence (UCL) spectra of the nanophosphors of NaYF4: Yb3+,
Er3+@ silica/TPGS under NIR laser excitation at exc = 980nm
Fluorescence results of the materials Fig, 4.15 and Fig.4.17 show that all materials emitted blue at
wavelengths (510 nm ÷ 570 nm) and red at wavelengths (630 nm ÷ 700 nm) corresponding to 2H11/2 → 4I15/2;
4
S3/2 → 4I15/2 and 4F9/2 → 4I15/2 of Er3+ ions. However, when fitted with FA, NaYF4: Yb3+, Er3+ @ silica-N =
FA materials still glow UCL although the luminescence intensity of this sample is weaker than that of nonFA models.
3+
3+
(1) NaYF4:Yb , Er

4
F9/2- I15/2

3+
3+

(2) NaYF4:Yb , Er @silica
3+
3+
(3) NaYF4:Yb , Er @silica-NH2

Intensity (a.u)

4

3+
3+
(4) NaYF4:Yb , Er @silica-N=FA

(3)

4
3/2- I15/2

(d)

4S

(1)

2
H

11/2

4

- I

15/2

(2)

500

550

600

650

700

750

Wavelength (nm)

Hình 4.17. The upconversion luminescence (UCL) spectra of the nanophosphors of
NaYF4:Yb3+,Er3+(1); NaYF4:Yb3+,Er3+@silica (2); NaYF4: Yb3+, Er3+@silica-NH2 (3) and NaYF4:
Yb3+, Er3+@silica-N=FA (4) at exc = 980nm
4.3. Result of application upconversion luminescent nanomaterials to identify MCF7 cancer cells
In vitro cellular imaging was performed to prove the localization of the functionalized UCNPs within
the cytoplasm of breast cancer cells. The UCNPs were incubated the with MCF-7 cells for 24 hours. We
observed the UCNPs have been clearly localized within the cell cytoplasm by microscope with no significant
signs of cytotoxicity. The evidence confirms that the UCNPs can be potentially used as bio-labels for MCF-7

23
breast cancer cells. This is possible because the high affinity via FA–FR. After the binding of the ligands, the
UCNPs is internalized into the cell via invagination process.
Fig. 4.19 demonstrates imaging results of biological test for UCNPs. In Fig. 4.19 (a), we show images
of MCF7 cells only in three cases: upper one is a bright field image, middle one is a dark field image, lower
one is merged image of two above pictures. Similarly, Fig. 6 (b) presents images for the case of MCF7 cells
after incubated with NaYF4:Yb3+, Er3+@silica-N=FA. When we use right field regime of microscope, we
only see a typical MCF7 cell type, in both cases (a) and (b). For the dark field images, we do not see
luminescence from bare MCF7 cells but we observed the brightness emitting dots in the MCF7 incubated
with UCNPs. The merge pictures show clearly that the brightness emitting dots (represent for existance of
UCNPs) were attached around MCF7 cells. This indicated that the rich folate receptor was captured to the
MCF7 cells.
Bright field

Dark field

Merge

MCF7 cells

MCF7

3+

NaYF4: Yb ,
3+

Er @silicaNH2
MCF7

3+

NaYF4: Yb ,
3+

Er @ silicaN=FA
Fig. 4.19. Upconversion fluorescent imaging of MCF7 cells and MCF7 cells after incubated with
NaYF4:Yb3+, Er3+@Silica-N=FA was observed by reverse fluorescence microscope.
Thus, through rigorous samples showed that folate groups were attached to MCF7 cells or in other
words, biomedical nanoparticles: NaYF4: Yb3+, Er3+ @ silica – N = FA were paired on the surface of MCF7
breast cancer cells. The pairing position of this nanoscale with cancer cells was observed by reverse
microscopy Zeiss axio vert A1. The results showed that for the first time using biomedical nanoparticles:
NaYF4: Yb3+, Er3+ @ silica – N = FA attached to MCF7 breast cancer cells and surveyed on the backilluminated fluorescence microscope Zeiss axio vert A1 has shown that the biomedical nanoparticles:
NaYF4: Yb3+, Er3+ @ silica – N = FA can be used as a marker for identifying breast cancer cells MCF7 in
vitro.