Thesis Format

Monograph

Development of Carbon-based Nano-structural Fluorescent Biosensor

Yingqi Zhang, The University of Western OntarioFollow

Degree

Doctor of Philosophy

Program

Chemical and Biochemical Engineering

Supervisor

Dr. Zhang, Jin

Abstract

Detection systems with high sensitivity and selectivity are critical for daily health monitoring and clinical diagnostics. Nanomaterials have shown great potentials in user-friendly biomedical devices, such as biosensors, because of their special chemical and physical properties. Recently, carbon-based nanostructures have attracted great attentions in the application of miniaturized biomedical devices because of their enhanced optical properties and biocompatibility. Herein, this thesis focuses on developing carbon-based nanostructured biosensing systems by employing advanced fluorescence technologies.

Gene detection is vital for early-stage diagnosis of diseases, e.g., breast cancer. The first sensing system has been developed to quantitatively detect breast cancer-associated gene by using fluorescence resonance energy transfer (FRET) quenching mechanism. Carbon quantum dots (CQDs) acted as the FRET donor to generate the emission, λ_em=510nm, which can be quenched by graphene oxide nanosheets (GONSs) which is used as the FRET quencher. In the presence of the target DNA sequence, the fluorescence intensity (I_max) can be restored. The detection range of this DNA sensing system is from 0.25 to 2.5 μM. The limit of the detection (LOD) is around 0.24 μM. The carbon-based FRET sensing system can be further developed to detect monosaccharide, e.g. D-glucose. Concanavalin A (Con A) has been conjugated on CQDs which are linked to the dextran-conjugated GONSs. Due to the competitive reaction between the dextran and the glucose with Con A, the homogeneous carbon-based sensing system can measure glucose from 0.02 mM to 0.1 mM with the LOD around 0.0127 mM. In addition, carbon-based biosensing systems have been used to quantitatively measure lactoferrin (LF), one of the major functional proteins in maintaining human health due to its antioxidant, antibacterial, antiviral, anti-inflammatory activities. Two different fluorescence technologies have been employed in the design of carbon nanostructure-based LF biosensors; (1) FRET quenching and (2) fluorescence polarization (FP). Due to a stronger binding affinity between LF and a chosen aptamer, the GONSs coupled with the aptamer-conjugated CQDs can be replaced by LF which results in the restoration of I_max. LF can be detected from 4 μg/mL to 18 μg/mL which have an ability to diagnose Alzheimer’s disease by using salivary LF as biomarker. On the other hand, LF bonded to the aptamer-conjugated CQDs can make the degree of fluorescence polarization changed in the solution-based carbon nanostructured biosensing system. The results indicate that this FP-based biosensor can be used to detect tear LF, considered as biomarker of dye eye disease.

In summary, carbon nanostructured-based biosensing systems integrating with advanced fluorescence technologies have been developed for quantitatively detecting different biomolecules. The high sensitivity and selectivity of the developed carbon nanostructured-based biosensing systems could benefit in early-stage diagnosis of diseases.

Summary for Lay Audience

Abstract

Detection systems with high sensitivity and selectivity are critical for daily health monitoring and clinical diagnostics. Nanomaterials have shown great potentials in user-friendly biomedical devices, such as biosensors, because of their special chemical and physical properties. Recently, carbon-based nanostructures have attracted great attentions in the application of miniaturized biomedical devices because of their enhanced optical properties and biocompatibility. Herein, this thesis focuses on developing carbon-based nanostructured biosensing systems by employing advanced fluorescence technologies.

Gene detection is vital for early-stage diagnosis of diseases, e.g., breast cancer. The first sensing system has been developed to quantitatively detect breast cancer-associated gene by using fluorescence resonance energy transfer (FRET) quenching mechanism. Carbon quantum dots (CQDs) acted as the FRET donor to generate the emission, λ_em=510nm, which can be quenched by graphene oxide nanosheets (GONSs) which is used as the FRET quencher. In the presence of the target DNA sequence, the fluorescence intensity (I_max) can be restored. The detection range of this DNA sensing system is from 0.25 to 2.5 μM. The limit of the detection (LOD) is around 0.24 μM. The carbon-based FRET sensing system can be further developed to detect monosaccharide, e.g. D-glucose. Concanavalin A (Con A) has been conjugated on CQDs which are linked to the dextran-conjugated GONSs. Due to the competitive reaction between the dextran and the glucose with Con A, the homogeneous carbon-based sensing system can measure glucose from 0.02 mM to 0.1 mM with the LOD around 0.0127 mM. In addition, carbon-based biosensing systems have been used to quantitatively measure lactoferrin (LF), one of the major functional proteins in maintaining human health due to its antioxidant, antibacterial, antiviral, anti-inflammatory activities. Two different fluorescence technologies have been employed in the design of carbon nanostructure-based LF biosensors; (1) FRET quenching and (2) fluorescence polarization (FP). Due to a stronger binding affinity between LF and a chosen aptamer, the GONSs coupled with the aptamer-conjugated CQDs can be replaced by LF which results in the restoration of I_max. LF can be detected from 4 μg/mL to 18 μg/mL which have an ability to diagnose Alzheimer’s disease by using salivary LF as biomarker. On the other hand, LF bonded to the aptamer-conjugated CQDs can make the degree of fluorescence polarization changed in the solution-based carbon nanostructured biosensing system. The results indicate that this FP-based biosensor can be used to detect tear LF, considered as biomarker of dye eye disease.

In summary, carbon nanostructured-based biosensing systems integrating with advanced fluorescence technologies have been developed for quantitatively detecting different biomolecules. The high sensitivity and selectivity of the developed carbon nanostructured-based biosensing systems could benefit in early-stage diagnosis of diseases.

Keywords

Fluorescent biosensor, Carbon-based nanomaterial, Carbon quantum dots, Graphene oxide nanosheets, Fluorescence resonance energy transfer, Fluorescence polarization.

Co-Authorship Statement

Chapter 1 and chapter 2 entitled “General Introduction and Motivation” and “Background and Literature Review”, respectively, were written by Yingqi Zhang with suggestions from Dr. Jin Zhang. Copyrights for all cited figures are list under Appendices in the end.

Chapter 3, chapter 4, chapter 5, chapter 6 and chapter 7 encompass my research works that have been published, submitted or are in preparation for publication.

Chapter 4: This chapter consists of one research study which has been submitted. The research study is focused on developing fluorescence resonance energy transfer-based biosensor for detecting target ssDNA. Yingqi Zhang (Chemical and Biochemical Engineering, UWO) contributed to all experiments and wrote the first draft of the manuscript individually. Jisu Song (Biomedical Engineering, UWO) helped to review the manuscript. Dr. Songlin Yang (Chemical and Biochemical Engineering, UWO) assisted with the synthesis of graphene oxide used in this study. Dr. Jin Zhang supervised this work and reviewed/revised the manuscript.

Yingqi Zhang, Jisu Song, Songlin Yang and Jin Zhang (2022) “Carbon Nanostructure-based DNA Sensor Used for Quickly Detecting Breast Cancer-associated Genes” (Under Revision)

Chapter 5: This chapter consists of one research study that in preparation. The research study is focused on developing fluorescence resonance energy transfer-based biosensor for detecting glucose. All experiment work involved in this part obtained by Yingqi Zhang (Chemical and Biochemical Engineering, UWO) and finished writing the first draft of the manuscript individually. Dr. Jin Zhang supervised this work and reviewed/revised the manuscript.

Yingqi Zhang and Jin Zhang (2022) “A Nanostructured Biosensor to Detect Glucose by Using Carbon-based Nanomaterials via Fluorescence Resonance Energy Transfer (FRET)” (In Preparation)

Chapter 6: This chapter consists of one literature review which has been published and one research study which is under revision.

The literature review (Nutrients 13.8 (2021): 2492) about the introduction of lactoferrin and its current detection methods. Yingqi Zhang (Chemical and Biochemical Engineering, UWO) and Chao Lu (Chemical and Biochemical Engineering, UWO) wrote the first draft of the manuscript. Dr. Jin Zhang supervised this work and reviewed/revised the manuscript.

Zhang, Yingqi, Chao Lu, and Jin Zhang. "Lactoferrin and its detection methods: a review." Nutrients 13.8 (2021): 2492.

The research study is focused on developing fluorescence resonance energy transfer-based biosensor for detecting lactoferrin. The experiment work in this part was carried out by Yingqi Zhang (Chemical and Biochemical Engineering, UWO). Dr. Jin Zhang supervised this work and reviewed/revised the manuscript.

Yingqi Zhang, Jin Zhang (2022) “FRET-based Aptasensor Made of Carbon-based Nanomaterials for Detecting Low Concentration of Lactoferrin” (Under Revision)

Chapter 7: This chapter consists of one literature review which has been published and one research study which has been submitted.

The literature review about using nanomaterials for building fluorescent polarization based biosensing systems. Yingqi Zhang (Chemical and Biochemical Engineering, UWO) conceptualized the review and worked with Howyn Tang (Biomedical Engineering, UWO) and Wei Chen (Chemical and Biochemical Engineering, UWO) to write the first draft of the manuscript. Dr. Jin Zhang supervised this work and reviewed/revised the manuscript.

Zhang, Yingqi, Howyn Tang, Wei Chen, and Jin Zhang. "Nanomaterials Used in Fluorescence Polarization Based Biosensors." International Journal of Molecular Sciences 23, no. 15 (2022): 8625.

The research study is focused on developing fluorescence polarization-based biosensor for detecting tear lactoferrin. The experiment work in this part was mainly achieved by Yingqi Zhang (Chemical and Biochemical Engineering, UWO) with suggestion from Dr. Jin Zhang. Yingqi Zhang did all of the test, data analysis and wrote the first draft of the manuscript individually. Dr. Jin Zhang supervised this work and reviewed/revised the manuscript.

Yingqi Zhang, and Jin Zhang (2022) “Rapid Dry Eye Disease Diagnosis by Using Nanostructured Fluorescence Polarization-based Aptasensor” (Submitted)

Chapter 8 entitled “Summary and Recommendations” was written by Yingqi Zhang with suggestions from Dr. Jin Zhang.

Acknowledgements

This thesis cannot be finished successfully without helps from several people around me. Thus, I want to offer my thanks to all of them.

Without the help of my supervisor Dr. Jin Zhang, I cannot achieve that many goals in these four years. Her support and trust encouraged me a lot in my career. Since the first day I came to her lab, she always be patience on teaching me how to be an independent researcher. As I do not have that much experience in this field, she helped me a lot in improving my abilities and shared her experience to me. She also provided opportunities to me to attend conferences for enhancing my skills in academic communications.

Besides, I would like to give my appreciate to my lab colleagues: Dr. Longyi Chen, Dr. Xueqin Zhao, Chao Lu and especially Howyn Tang who support me a lot in many fields. We are not only a research group, but also a family. I am grateful for having a chance to be a member of at Dr. Jin Zhang’s Multifunctional Nanocomposites Lab (MNL) as I learned a lot of things here, not only in researches, but also in life.

Meanwhile, I also appreciate to many people outside of our lab. I want to thank Dr. Nataphan Sakulchaicharoen from Engineering undergraduate lab for nicely teaching me and giving me many suggestions on testing UV-vis and FTIR. I want to thank Reza Khazaee and Karen Nygard from Biotron for patiently teaching me and helping me on TEM and SEM. I want to thank Dr. Victoria Clarke and Dr. Lee-Ann Briere from Department of Biochemistry for kindly teaching me and assisting me on measuring fluorescence polarization.

I also want to provide my appreciate to my examination committees: Dr. Dongyang Li, Dr. Lijia Liu, Dr. Michael Boutilier, Dr. Shahzad Barghi.

Finally, I would like to say “thank you so much” to my mom, she always be very kind to me even though I complained to her sometimes and very welling to hear my troubles and help me to go through them. Also my dad, maybe we not talked that much, but his financial support made me can focus on my researched and studies.

This work has been supported by funding from Natural Science and Engineering Research Council of Canada (NSERC).

List of Tables

Table 1.1‑1 Comparison of using fluorescent nanomaterials or organic dyes in developing fluorescent biosensing system. 5

Table 1.1‑2 Comparison of using nanomaterials or other amplifiers in FP-based biosensing system. 6

Table 2.4‑1 Comparison of different methods for detecting lactoferrin. Reprinted with permission from ref⁶⁸. (Permission in Appendix 1) 30

Table 2.5‑1 Strengths and weaknesses of different types of fluorescent biosensors. 31

Table 2.7‑1Functional Groups and Strategies applied for Covalent Binding between Nanomaterials and Biomolecules. 42

Table 7.3‑1 Concentration of human tear sample determined by different methods. 138

List of Figures

Figure 1.1.1 Schematic of biosensor. 2

Figure 1.1.2 Mechanism of demonstrating the processes in emitting fluorescence. 8

Figure 1.1.3 Mechanism of fluorescence resonance energy transfer (FRET). 9

Figure 1.1.4 Schematic of fluorescence resonance energy transfer (FRET) process. 10

Figure 1.1.5 Schematic of fluorescence polarization principle and its amplification mechanism. 12

Figure 1.2.1 Basic strategy of using nanomaterials in developing optical biosensing devices. 13

Figure 1.3.1 Goals of my studies of the thesis. 15

Figure 2.1.1 Classification of biosensors. 27

Figure 2.5.1 An antibody-free microfluidic paper-based analytical device (μPAD) for the determination of tear fluid lactoferrin. (A) Terbium-lactoferrin fluorescence emission is utilized by energy transfer to terbium through tyrosine at the binding site. (B) Visualization of transported lactoferrin on μPAD. The length of the fluorescent line increased in proportion to the lactoferrin concentration in the tear fluid samples. (C) Outline of the μPAD for distance-based lactoferrin measurement. Reprinted with permission from ref¹⁸. (Permission in Appendix 2) 33

Figure 2.5.2 The sensing mechanism of the proposed graphene quantum dots (GQDs)–gold nanoparticles (AuNPs) FRET biosensor for Staphylococcus aureus gene detection. Reprinted with permission from ref⁸⁵. (Permission in Appendix 3) 34

Figure 2.5.3 Schematic illustration of the fluorescence polarization immunoassay for antibody detection. Reprinted with permission from ref⁸⁶. (Permission in Appendix 4) 35

Figure 2.6.1The Schematic Structures of Carbon Quantum Dots (CQDs). Reprinted with permission from ref⁹³. (Permission in Appendix 5) 37

Figure 2.6.2 Schematic illustration of the construction of FRET assembly by using carbon quantum dots (CQDs) and gold nanorods (Au NRs) and their application as an off-on fluorescent detection of Pb²⁺ions. Reprinted with permission from ref⁹⁵. (Permission in Appendix 6) 38

Figure 2.6.3 Structures of graphene-based materials: (a) pristine graphene; (b) graphene oxide (GO); (c) reduced graphene oxide (RGO). Reprinted with permission from ref¹⁰¹. (Permission in Appendix 7) 39

Figure 2.6.4 Schematic illustration of MMP-2 detection by a FRET biosensor probe constructed through covalent conjugation of FITC-labeled peptide and graphene oxide nanosheets (GONSs). Reprinted with permission from ref¹⁰⁵. (Permission in Appendix 8) 40

Figure 2.6.5 HIV DNA detection based on T7exonuclease assisted target recycling amplification. GONSs acted as the FP amplifier. Reprinted with permission from ref¹⁰⁶. (Permission in Appendix 9) 41

Figure 3.1.1 General synthesis methods of CQDs. Bottom-up approach: CQDs are synthesized from smaller carbon units (small organic molecules) via applying energy (electrochemical/chemical, thermal, laser, etc.). The source molecules are getting ionized, dissociated, evaporated or sublimated and then condensed to form CQDs. Top-down approach: CQDs are synthesized by transformation of larger carbon structures into ultra-small fragments via applying energy (thermal, mechanical, chemical, ultrasonic, etc.) Reprinted with permission from ref³. (Permission in Appendix 10) 59

Figure 3.1.2 (A) Fabrication process of carbon quantum dots; (B) Purification process of carbon quantum dots. 60

Figure 3.1.3 Color of different CQDs under (A) visible Light; (B) ultraviolet Light. 61

Figure 3.1.4 Photoluminescence spectra of CQDs-4 under different λ_ex from 300 nm to 500 nm. 62

Figure 3.1.5 Sample of CQDs-4. 62

Figure 3.1.6 TEM Micrograph of CQDs-4; small inset is the HRTEM micrograph of CQDs-4. 63

Figure 3.1.7 Photoluminescence Spectra of CQDs-4 with Different Concentrations under λ_ex=400 nm. 64

Figure 3.1.8 Photoluminescence Spectra of CQDs-4 under Different Temperatures with λ_ex=400 nm. 64

Figure 3.1.9 Photoluminescence Spectra of CQDs-4 under Different pH with λ_ex=400 nm: (A) from pH=1 to pH=7; (B)from pH=8 to pH=14. 66

Figure 3.1.10 Color of CQDs-4 with Different pH under (A) Visible Light (from pH=1 to pH=7); (B) Visible Light (from pH=8 to pH=14); (C) Ultraviolet Light (from pH=1 to pH=7); (D) Ultraviolet Light (from pH=8 to pH=14). 67

Figure 3.2.1 Synthesis of graphene oxide nanosheets. 68

Figure 3.2.2 Sample of GONSs. 69

Figure 3.2.3 TEM micrograph of GONSs. 69

Figure 3.2.4 UV-vis spectrum of GONSs. 70

Figure 4.1.1 Illustration of the carbon nanostructure-based DNA sensor by using the fluorescence quenching mechanism. 76

Figure 4.3.1 TEM micrograph of CQDs, the small inset is the HRTEM micrograph of CQDs. 79

Figure 4.3.2 UV-vis absorbance spectra of (A) Amino-modified Capture ssDNA, (B) CQDs, and (C) CQDs-Capture ssDNA. 80

Figure 4.3.3 FTIR spectra of CQDs, amino-Capture ssDNA, and CQDs-Capture ssDNA. 81

Figure 4.3.4 The photoluminescence (PL) of CQDs under different excitation wavelengths. 82

Figure 4.3.5 UV-vis absorbance of graphene oxide nanosheets (GONSs). 83

Figure 4.3.6 TEM micrograph of GONSs. 83

Figure 4.3.7 The photoluminescence (PL) properties of the carbon nanostructure-based DNA sensor used to detect target ssDNA. (A) PL of CQD-Capture ssDNA and CQD-Capture ssDNA-GONSs under λ_ex=400 nm; and the restoration of PL of CQD-Capture ssDNA-GONSs when it is introduced the complementary target ssDNA with different concentrations. (B) A linear relationship between the normalized maximum fluorescence intensity (I_max) and the concentration of complementary Target ssDNA. 84

Figure 4.3.8 The selectivity study by detecting the mismatch sequences with the same concentration of complementary Target ssDNA. 85

Figure 5.1.1 Scheme of biosensing mechanism for detecting glucose. 92

Figure 5.3.1 UV-vis spectra of (A) CQDs, (B) Con A, and (C) CQDs-Con A. 95

Figure 5.3.2 FTIR spectra of CQDs, Con A and CQDs-Con A. 96

Figure 5.3.3 Normalized photoluminescence (PL) spectra of CQDs and CQDs-Con A. 97

Figure 5.3.4 UV-vis spectra of amino-Dextran, GONSs, and GONSs-dextran. 98

Figure 5.3.5 FTIR spectra of amino-Dextran, GONSs, and GONSs-dextran. 99

Figure 5.3.6 Photoluminance of CQDs excited under difference excitation wavelengths from 320 nm to 440 nm. 100

Figure 5.3.7 UV-vis absorbance spectrum of GONSs-dextran and fluorescence emission spectrum of CQDs-Con A (at λ_ex= 400nm). 101

Figure 5.3.8 Photoluminescence (PL) spectra of: (A) GONSs-dextran titration of CQDs-Con A under λ_ex=400 nm; (B) relationship of the titration. 102

Figure 5.3.9 Photoluminescence changes of: (A) different time for GONSs-dextran to quench CQDs-Con A from 0 to 12 hrs; (B) relationship between fluorescence intensity and quenching time. 103

Figure 5.3.10 Performance of the biosensing system to detect prepared glucose standard solution in different concentrations from 0.02 mM to 0.1 mM under λ_ex=400 nm: (A) PL spectra of biosensing system before and after quenching (in black and red, respectively) and after introducing glucose samples in different concentrations from 0.02 mM to 0.1 mM; (B) the linear relationship between the fluorescence intensity of emission wavelength at 510 nm and glucose concentrations within the range of 0.02-0.1 mM. 104

Figure 5.3.11 The selective study by using the designed glucose biosensor to detect different analytes: glucose, fructose, rhamnose, lactose, maltose. 104

Figure 6.1.1 Schematic demonstration of nano-structural FRET-based aptasensor by using carbon-based nanomaterials to detect lactoferrin. 112

Figure 6.2.1 UV-vis spectra of: Sample 1-0.4 mg CQDs+100uL 10 uM aptamers; Sample 2-0.4 mg CQDs+200uL 10 uM aptamers; Sample 3-0.4 mg CQDs+300uL 10 uM aptamers; Sample 4-0.4 mg CQDs+400uL 10 uM aptamers; Sample 5-0.4 mg CQDs+500uL 10 uM aptamers. 114

Figure 6.3.1 TEM micrograph of CQDs; small inset is the HRTEM of CQDs.. 114

Figure 6.3.2 FTIR spectra of CQDs, amino-aptamer and CQDs-aptamer. 115

Figure 6.3.3 The photoluminescence spectra of CQDs-aptamer under different excitation wavelengths (λ_ex) from 345 nm to 465 nm. 116

Figure 6.3.4 UV-vis absorbance spectrum of GONSs and fluorescence emission spectrum of CQDs (at λ_ex=365 nm). 117

Figure 6.3.5 Photoluminescence (PL) spectra of CQDs-aptamer under λ_ex=365 nm when the concentration of GO increases. 118

Figure 6.3.6 Linear relationship between the fluorescence intensity of the CQDs-aptamer-GONSs system and the concentration of LF by introducing LF standard solution in different concentrations and the fluorescence intensities are measured under λ_ex=365 nm). 119

Figure 6.3.7 The performance of the designed lactoferrin aptasensor responding to different proteins with the same concentration of 0.2 μM. (Lactoferrin: lactoferrin from bovine colostrum; Peroxidase: concanavalin A-peroxidase from Canavalia ensiformis; β-Casein: β-casein from bovine milk; Lysozyme: lysozyme human; Albumin: albumin from bovine serum.) 120

Figure 7.1.1 Scheme of carbon-based nano-structural aptasensor for the detection of lactoferrin. 128

Figure 7.3.1 Photoluminescence spectra (Normalized) of CQDs under different excitation wavelengths. 132

Figure 7.3.2 Agarose gel electrophoresis image of free CQDs and 0.4 mg CQDs conjugated with different volumes of 10 μM aptamers: sample 1-0.4 mg CQDs +100 μL 10 μM aptamers; sample 2-0.4 mg CQDs +200 μL 10 μM aptamers; sample 3-0.4 mg CQDs +300 μL 10 μM aptamers; sample 4-0.4 mg CQDs +400 μL 10 μM aptamers; sample5-0.4 mg CQDs +500 μL 10 μM aptamers. 133

Figure 7.3.3 FTIR spectra of CQDs, amino-aptamer and CQDs-aptamer. 133

Figure 7.3.4 TEM micrographs of (A) GONSs; (B) CQDs-aptamer on GONSs. 134

Figure 7.3.5 FP value of free CQDs, CQDs-aptamer and CQDs-aptamer-GONSs. 135

Figure 7.3.6 (A) FP signal of detecting lactoferrin in different concentrations in standard LF solution and standard LF solution extracted from Schirmer Strip; (B) linear relationship between FP value and different concentrations of standard LF solution extracted from Schirmer Strip. 136

Figure 7.3.7 Selectivity studies of the designed FP-based LF aptasensor with adding 1X PBS, lysozyme, oxidase, peroxidase, β-casein, albumin and lactoferrin standard solutions. (Lysozyme: lysozyme human; Oxidase: glucose oxidase from aspergillus niger; Peroxidase: concanavalin A-peroxidase from canavalia ensiformis; β-Casein: β-casein from bovine milk; Albumin: albumin from bovine serum; Lactoferrin: lactoferrin from bovine colostrum.) 137

Figure 7.3.8 Strategy to collect tear sample from Schirmer Strip. 138

Figure 8.1.1 Schematic of My PhD Work. 145

Figure 8.2.1 Schematic of Carbon-based Biosensing Systems: (A) FRET-based Biosensor for Detecting Oligonucleotides; (B) FRET-based Biosensor for Detecting Monosaccharides; (C) FRET-based Biosensor for Detecting Proteins; (D) FP-based Biosensor for Detecting Proteins. 151

List of Abbreviations

AD

Ag NPs

AIV

ARMS

Au NPs

Au NRs

BRCA

CNTs

CdTe

CdSe

CE

CEA

CQDs

CQDs-aptamer

CQDs-Con A

Con A

Con A-dextran

CSF

DED

DNA

dsDNA

EDC

ELISA

FA

FI

FITC

FP

FPIA

Alzheimer’s diseases

Silver nanoparticles

Avian influenza virus

Amplification refractory mutation system

Gold nanoparticles

Gold nanorods

Breast Cancer genes

Carbon nanotubes

Cadmium telluride

Cadmium Selenide

Capillary electrophoresis

Carcinoembryonic antigen

Carbon Quantum Dots

Carbon Quantum Dots conjugated with aptamer of lactoferrin

Carbon Quantum Dots conjugated with Concanavalin A

Concanavalin A

Concanavalin A bonded to dextran

cerebrospinal fluid

Dry eye disease

Deoxyribonucleic acid

Double-stranded deoxyribonucleic acid

N-(3-Dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride

Enzyme-linked immunosorbent assay

Fluorescence Anisotropy

Fluorescence intensity

Fluorescein isothiocyanate

Fluorescence Polarization

Fluorescence polarization immunoassay

FRET

FTIR

GO

GONSs

GO-Dextran

HPLC

HRM

HRTEM

IBD

RFLP

RGO

RID

RP-HPLC

LF

LOD

LSPR

MMP

NHS

P/A value

PBS

PCR

PDMS

QDs

RT

SELEX

SSCP

ssDNA

SWCNTs

TEM

UTI

UV-vis

Fluorescence Resonance Energy Transfer

Fourier Transform Infrared Spectroscopy

Graphene Oxide

Graphene Oxide Nanosheets

Graphene oxide conjugated with dextran

High performance liquid chromatography

High-resolution melting curve

High-resolution Transmission electron microscopy

Inflammatory bowel disease

Restriction fragment length polymorphism

Reduced graphene oxide

Radial immunodiffusion

Reversed phase-high performance liquid chromatography

Lactoferrin

Limit of detection

Localized Surface Plasmon Resonance

Matrix metalloproteinases

N-Hydroxysuccinimide

Polarization/ Anisotropy value

Phosphate Buffered Saline

Polymerase chain reaction

Polydimethylsiloxane

Quantum Dots

Room temperature

Systematic Evolution of Ligands by EXponential Enrichment

Single-strand conformation polymorphism

Single-stranded deoxyribonucleic acid

Single-walled carbon nanotubes

Transmission electron microscopy

Urinary tract infection

Ultraviolet Visible

WHO

μPAD

α-AFP

World Health Organization

Microfluidic paper-based analytical device

Alpha-fetoprotein

Summary for Lay Audience

Recently, health-related problems have caught many attentions. However, conventional strategies used for diagnostics or maintaining good health are expensive or uncomfortable. Nanotechnology combined with biotechnology, considered as nano-biotechnology, has been introduced in developing various biomedical applications, such as different biosensing systems and drug delivery systems.

The biomarker can be considered as an indicator of normal biological processes. Meanwhile, fluorescent signals are usually considered with fast responses and with high sensitivity. Thus, my objectives are going to obtain the sensitive and selective fluorescent biosensing systems for the quantitative detection of biomolecules. Carbon-based nanomaterials, with unique properties, are considered as promising candidates to enhance the performance of biosensing. As biomarkers have been involved in diagnosing various diseases, my studies are focusing on using carbon-based nanomaterials assisted with fluorescent technologies to build biosensing systems for diagnosing different diseases.

Four different fluorescent biosensors have been investigated in my thesis. The first one can help to diagnose breast cancer at the early stage by detecting the mutant genes. The second one can be used to monitor glucose levels in tear samples. The third one can be used for predicting Alzheimer's disease by determining the salivary lactoferrin levels. The fourth one can help the diagnosis of dry eye disease. If these applications are commercialized, many benefits will be brought in our daily lives. The risk of breast cancer will be dramatically decreased if the mutant genes can be detected and corrected at early stages. Diabetes do not need to prick fingers several times to get blood samples for the measurement. Alzheimer's disease may be able to be prevented. In addition, the severity of dry eye disease can be determined followed by specific treatments.

Recommended Citation

Zhang, Yingqi, "Development of Carbon-based Nano-structural Fluorescent Biosensor" (2022). Electronic Thesis and Dissertation Repository. 8749.
https://ir.lib.uwo.ca/etd/8749

Thesis Format

Development of Carbon-based Nano-structural Fluorescent Biosensor

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Supervisor

Abstract

Summary for Lay Audience

Abstract

Co-Authorship Statement

Acknowledgements

Table of Contents

List of Tables

List of Figures

List of Abbreviations

Summary for Lay Audience

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Thesis Format

Development of Carbon-based Nano-structural Fluorescent Biosensor

Author

Degree

Program

Supervisor

Abstract

Summary for Lay Audience

Abstract

Co-Authorship Statement

Acknowledgements

Table of Contents

List of Tables

List of Figures

List of Abbreviations

Summary for Lay Audience

Recommended Citation

Included in

Share

Links

Browse

Author Corner

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