Gold Nanoparticle-based Novel Biosensors for Detecting Glycated Hemoglobin

Advances in Nanomaterial-Based Biosensors for Determination of Glycated Hemoglobin

Diabetes is a major public health burden whose prevalence has been steadily increasing over the past decades. Glycated hemoglobin (HbA1c) is currently the gold standard for diagnostics and monitoring glycemic control in diabetes patients. HbA1c biosensors are often considered to be cost-effective alternatives for smaller testing laboratories or clinics unable to access other reference methods. Many of these sensors deploy nanomaterials as recognition elements, detection labels, and/or transducers for achieving sensitive and selective detection of HbA1c. Nanomaterials have emerged as important sensor components due to their excellent optical and electrical properties, tunable morphologies, and easy integration into multiple sensing platforms. In this review, we discuss the advantages of using nanomaterials to construct HbA1c sensors and various sensing strategies for HbA1c measurements. Key gaps between the current technologies with what is needed moving forward are also summarized.

Gold nanoparticle-based optical nanosensors for food and health safety monitoring: recent advances and future perspectives

Modern society has been facing serious health-related problems including food safety, diseases and illness. Hence, it is urgent to develop analysis methods for the detection and control of food contaminants, disease biomarkers and pathogens. As the traditional instrumental methods have several disadvantages, including being time consuming, and having high cost and laborious procedures, optical nanosensors have emerged as promising alternative or complementary approaches to those traditional ones. With the advantages of simple preparation, high surface-to-volume ratio, excellent biocompatibility, and especially, unique optical properties, gold nanoparticles (AuNPs) have been demonstrated as excellent transducers for optical sensing systems. Herein, we provide an overview of the synthesis of AuNPs and their excellent optical properties that are ideal for the development of optical nanosensors based on local surface plasmon resonance (LSPR), colorimetry, fluorescence resonance energy transfer (FRET), and surface-enhanced Raman scattering (SERS) phenomena. We also review the sensing strategies and their mechanisms, as well as summarizing the recent advances in the monitoring of food contaminants, disease biomarkers and pathogens using developed AuNP-based optical nanosensors in the past seven years (2015-now). Furthermore, trends and challenges in the application of these nanosensors in the determination of those analytes are discussed to suggest possible directions for future developments.

Electrochemiluminescence paper-based screen-printed electrode for HbA1c detection using two-dimensional zirconium metal-organic framework/Fe3O4 nanosheet composites decorated with Au nanoclusters

Glycated hemoglobin (HbA1c) is one of the most popular biomarkers which can be utilized for the diagnosis and control of diabetes in clinical practice. In this study, a sandwich paper-based electrochemiluminescence (ECL) biosensor has been developed using the zirconium metal-organic framework/Fe₃O₄(trimethyl chitosan)/gold nanocluster (Zr-MOF/Fe₃O₄(TMC)/AuNCs) nanocomposite as tracing tag to label anti-HbA1c monoclonal antibody and reduced graphene oxide (rGO) as immobilization platform of sensing element. The screen-printed electrodes (SPEs) were constructed and modified by sputtering a thick layer of gold on the paper substrate, followed by electrochemical reduction of aminophenylboronic acid (APBA)-functionalized GO to rGO/APBA, respectively. Different types of surface analysis methods were applied to characterize the Zr-MOF/Fe₃O₄(TMC)/AuNCs nanomaterials fabricated. Finally, antibody-labeled Zr-MOF/Fe₃O₄(TMC)/AuNCs nanocomposites were subjected to HbA1c in the sample and on the paper-based SPE. Quantitative measurement of HbA1c was performed using ECL and cyclic voltammetry (CV) over a potential range of - 0.2 to 1.7 V vs gold reference electrode with a sweep rate of 0.2 V.s^-1 in the presence of triethylamine as a co-reactant after sandwiching the HbA1c target between antibody and APBA on the sensing area. This immunosensor demonstrated the desirable assay performance for HbA1c with a wide response range from 2 to 18% and a low detection limit (0.072%). This new strategy provides an effective method for high-performance bioanalysis and opens avenues for the development of high-sensitive and user-friendly device. Graphical abstract.

QCM sensing of miR-21 by formation of microRNA-DNA hybrid duplexes and intercalation on surface-functionalized pyrene

MicroRNAs (miRNAs) are small non-coding RNA molecules that serve as important biomarkers for a variety of diseases such as cancer and vascular disease. However, sensitive and accurate detection of miR-21 is very challenging in that up-regulation of miR-21 is highly associated with several types of malignant tumors. Here, quartz crystal microbalance (QCM) biosensors were developed for sensitive and specific detection of miR-21 through formation of miR-21-DNA hybrid duplexes and non-specific intercalation of surface-modified pyrene molecules. High selectivity for miR-21 over other miRNAs came from the specific hybridization between miR-21 and gold nanoparticle (AuNP)-conjugated complementary oligonucleotides of miR-21. High sensitivity was obtained through formation of intercalated complexes on the surface with subsequent gold staining signal amplification. Under optimum condition using this strategic approach, our novel QCM biosensors could detect miR-21 concentration as low as 3.6 pM in the entire linear range from 2.5 pM to 2.5 μM with a correlation coefficient of 0.989. In addition, these sensors did not work at all for other miRNAs based on their high selectivity. miR-21 in human brain total RNA and total RNA extracted from A549 cell line could also be successfully detected. Therefore, miRNA detection technology using QCM biosensors and their detection mechanisms have potential as alternatives in biological studies and clinical diagnosis.

Analytical techniques for the detection of glycated haemoglobin underlining the sensors

The increase in concentrations of blood glucose results arise in the proportion of glycated haemoglobin. Therefore, the percentage of glycated haemoglobin in the blood could function as a biomarker for the average glucose level over the past three months and can be used to detect diabetes. The study of glycated haemoglobin tends to be complex as there are about three hundred distinct assay techniques available for evaluating glycated haemoglobin which contributes to some differences in the recorded values from the similar samples. This review outlines distinct analytical methods that have evolved in the recent past for precise recognition of the glycated - proteins.

Sensitivity and reproducibility improvements in a human plasma immunoassay with removal of clotting factors

Interferences in human plasma immunoassay are severe challenge that affects the sensitivity and reproducibility of the assay. The clotting factor fibrinogen is a negatively charged protein and is one of the most common sources of interference in immunoassays, and its removal increases the sensitivity and reproducibility. Here, we present a highly sensitive and reproducible method for the detection of prostate specific antigen (PSA) in human plasma immunoassays. Protamine sulfate, a highly positively charged protein, was used to precipitate fibrinogen via ionic interaction to improve the sensitivity and reproducibility of human plasma immunoassay. In a sandwich ELISA for PSA using plasma and protamine-treated plasma samples, the limit of detection was improved from 413 pg/mL in plasma to 235 pg/mL in protamine-treated plasma samples, and the coefficient of variation known as a measure of reproducibility was significantly lowered by protamine treatment. The use of protamine sulfate in human plasma immunoassays for detection of PSA using quartz crystal microbalance (QCM) biosensors resulted in increased sensitivity and reproducibility by about 2-fold and 3-fold, respectively, relative to when not using protamine sulfate. Based on these results, protamine sulfate was the best choice to increase the sensitivity and reproducibility in immunoassays using plasma samples.

Highly sensitive piezoelectric immunosensors employing signal amplification with gold nanoparticles

We present a quartz crystal microbalance (QCM) immunosensor for highly sensitive detection of prostate-specific antigen (PSA) in a human serum immunoassay. In particular, in this study, we employed signal amplification using and enlarging gold nanoparticles. Because QCM measures the change of resonance frequency according to the mass change occurring on the sensor surface, we could quantitatively analyze PSA based on a tremendous increase in mass by sandwich immunoassay using AuNP-conjugated anti-PSA-detecting antibody enhanced with subsequent gold staining. The limit of detection of the PSA immunoassay in human serum without gold staining enhancement was 687 pg ml^-1 but was 48 pg ml^-1 with the gold staining-mediated signal amplification. That is, amplifying the signal resulted in increased sensitivity and reproducibility of immunoassay in a human serum.

Strategic Approaches for Highly Selective and Sensitive Detection of Hg2+ Ion Using Mass Sensitive Sensors

Here we present a quartz crystal microbalance (QCM) sensor for the highly selective and sensitive detection of Hg²⁺ ion, a toxic chemical species and a hazardous environmental contaminant. Hg²⁺ ion can be quantitatively measured based on changes in the resonance frequency of QCM following mass changes on the QCM sensor surface. The high selectivity for Hg²⁺ ion in this study can be obtained using a thymine-Hg²⁺-thymine pair, which is more stable than the adenine-thymine base pair in DNA. On the other hand, gold nanoparticles (AuNPs) and their size-enhancement techniques were used to amplify the QCM signals to increase the sensitivity for Hg²⁺ ion. With this strategic approach, the proposed QCM sensor can be used to quantitatively analyze Hg²⁺ ion with high selectivity and sensitivity. The detection limit was as low as 98.7 pM. The sensor failed to work with other metal ions at concentrations 1000-times higher than that of the Hg²⁺ ion. Finally, the recovery does not exceed 10% of the original value for the detection of Hg²⁺ ion in tap and bottled water. The results indicate acceptable accuracy and precision for practical applications.

Different strategies for detection of HbA1c emphasizing on biosensors and point-of-care analyzers

Measurement of glycosylated hemoglobin (HbA1c) is a gold standard procedure for assessing long term glycemic control in individuals with diabetes mellitus as it gives the stable and reliable value of blood glucose levels for a period of 90-120 days. HbA1c is formed by the non-enzymatic glycation of terminal valine of hemoglobin. The analysis of HbA1c tends to be complicated because there are more than 300 different assay methods for measuring HbA1c which leads to variations in reported values from same samples. Therefore, standardization of detection methods is recommended. The review outlines the current research activities on developing assays including biosensors for the detection of HbA1c. The pros and cons of different techniques for measuring HbA1c are outlined. The performance of current point-of-care HbA1c analyzers available on the market are also compared and discussed. The future perspectives for HbA1c detection and diabetes management are proposed.