Picomolar or beyond Limit of Detection Using Molecularly Imprinted Polymer-Based Electrochemical Sensors: A Review

Disposable graphene-oxide screen-printed electrode integrated with portable device for detection of SARS-CoV-2 in clinical samples

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnosis is the need of the hour, as cases are persistently increasing, and new variants are constantly emerging. The ever-changing nature of the virus leading to multiple variants, has brought an imminent need for early, accurate and rapid detection methods. Herein, we have reported the design and fabrication of Screen-Printed Electrodes (SPEs) with graphene oxide (GO) as working electrode and modified with specific antibodies for SARS-CoV-2 Receptor Binding Domain (RBD). Flexibility of design, and portable nature has made SPEs the superior choice for electrochemical analysis. The developed immunosensor can detect RBD as low as 0.83 fM with long-term storage capacity. The fabricated SPEs immunosensor was tested using a miniaturized portable device and potentiostat on 100 patient nasopharyngeal samples and corroborated with RT-PCR data, displayed 94 % sensitivity. Additionally, the in-house developed polyclonal antibodies detected RBD antigen of the mutated Omicron variant of SARS-CoV-2 successfully. We have not observed any cross-reactivity/binding of the fabricated immunosensor with MERS (cross-reactive antigen) and Influenza A H1N1 (antigen sharing common symptoms). Hence, the developed SPEs sensor may be applied for bedside point-of-care diagnosis of SARS-CoV-2 using miniaturized portable device, in clinical samples.

Gold Nanoparticles in Nanobiotechnology: From Synthesis to Biosensing Applications

Nanobiotechnology has ushered in a new era of scientific discovery where the unique properties of nanomaterials, such as gold nanoparticles, have been harnessed for a wide array of applications. This review explores gold nanoparticles' synthesis, properties, and multidisciplinary applications, focusing on their role as biosensors. Gold nanoparticles possess exceptional physicochemical attributes, including size-dependent optical properties, biocompatibility, and ease of functionalization, making them promising candidates for the development of biosensing platforms. The review begins by providing a comprehensive overview of gold nanoparticle synthesis techniques, highlighting the advantages and disadvantages of various approaches. It then delves into the remarkable properties that underpin their success in biosensing, such as localized surface plasmon resonance and enhanced surface area. The discussion also includes the functionalization strategies that enable specific binding to biomolecules, enhancing the sensitivity and selectivity of gold-nanoparticle-based biosensors. Furthermore, this review surveys the diverse applications of gold nanoparticles in biosensing, encompassing diagnostics, environmental monitoring, and drug delivery. The multidisciplinary nature of these applications underscores the versatility and potential of gold nanoparticles in addressing complex challenges in healthcare and environmental science. The review emphasizes the pressing need for further exploration and research in the field of nanobiotechnology, particularly regarding the synthesis, properties, and biosensing applications of gold nanoparticles. With their exceptional physicochemical attributes and versatile functionalities, gold nanoparticles present a promising avenue for addressing complex challenges in healthcare and environmental science, making it imperative to advance our understanding of their synthesis, properties, and applications for enhanced biosensing capabilities and broader scientific innovation.

Molecularly Imprinted Polymer-Based Sensors Integrated with Transition Metal Dichalcogenides (TMDs) and MXenes: A Review

Molecularly imprinted polymer (MIP)-based electrochemical sensors have been extensively researched due to their higher sensitivity, quick response, and operational ease. To develop more advanced sensing devices with enhanced properties, MIPs have been integrated with two-dimensional (2D) layered materials such as transition metal dichalcogenides (TMDs) and MXenes. These 2D materials have unique electronic properties and an extended surface area, making them promising sensing materials that can improve the performance of MIPs. In this review article, we describe the methods used for the synthesis of TMDs and MXenes integrated MIP-based electrochemical sensors. Furthermore, we have provided a critical review of a wide range of analytes determined through the application of these electrochemical sensors. We also go over the influence of TMDs and MXenes on the binding kinetics and adsorption capacity which has enhanced binding recognition and sensing abilities. The combination of TMDs and MXenes with MIPs shows promising synergy in the development of highly efficient recognition materials. In the future, these sensors could be explored for a wider range of applications in environmental remediation, drug delivery, energy storage, and more. Finally, we address the challenges and future perspectives of using TMDs and MXenes integrated MIPs. We conclude with a focus on future development and the scope of integrating these materials in sensing technology.

One-step synthesis of chiral molecularly imprinted polymer TiO2 nanoparticles for enantioseparation of phenylalanine in coated capillary electrochromatography

A novel chiral molecularly imprinted polymer TiO₂ nanoparticle was synthesized in one step for the enantioseparation of phenylalanine in coated capillary electrochromatography. To the author's knowledge, the chiral molecularly imprinted nanomaterials have still not been reported, to date. Chiral molecularly imprinted TiO₂ nanomaterials (L-PHE@MIP(APTES-TEOS)@TiO₂) were used as a chiral stationary phase to separate the phenylalanine enantiomers in coated capillary electrochromatography (CEC). The imprinted coating was prepared from L-phenylalanine (L-PHE) as the template, TiO₂ nanoparticles (NPs) as the support substrate, 3-aminopropyltriethoxysilane (APTES) as the functional monomer, and tetraethyl silicate (TEOS) as the cross-linker. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used for the characterization of the L-PHE@MIP(APTES-TEOS)@TiO₂@capillary. Fourier transform infrared spectra (FT-IR), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA) were employed for the characterization of the L-PHE@MIP(APTES-TEOS)@TiO₂. The effects of the applied voltage, pH value, buffer concentration, and acetonitrile content were investigated  experimentally to determine the optimum conditions for CEC. The best resolution for  phenylalanine enantiomers by CEC reached a value of 3.48. In addition, the specific recognition effect of L-PHE@MIP(APTES-TEOS)@TiO₂ on PHE enantiomers was studied by selective experiment. Finally, adsorption kinetic research, adsorption equilibrium isotherm study, and adsorption thermodynamic experiment were carried out to investigate the separation mechanism of PHE enantiomers with the L-PHE@MIP (APTES-TEOS)@TiO₂@capillary, and the results were consistent with those of CEC experiments.

Molecularly Imprinted Polymer-Based Sensors for the Detection of Skeletal- and Cardiac-Muscle-Related Analytes

Molecularly imprinted polymers (MIPs) are synthetic polymers with specific binding sites that present high affinity and spatial and chemical complementarities to a targeted analyte. They mimic the molecular recognition seen naturally in the antibody/antigen complementarity. Because of their specificity, MIPs can be included in sensors as a recognition element coupled to a transducer part that converts the interaction of MIP/analyte into a quantifiable signal. Such sensors have important applications in the biomedical field in diagnosis and drug discovery, and are a necessary complement of tissue engineering for analyzing the functionalities of the engineered tissues. Therefore, in this review, we provide an overview of MIP sensors that have been used for the detection of skeletal- and cardiac-muscle-related analytes. We organized this review by targeted analytes in alphabetical order. Thus, after an introduction to the fabrication of MIPs, we highlight different types of MIP sensors with an emphasis on recent works and show their great diversity, their fabrication, their linear range for a given analyte, their limit of detection (LOD), specificity, and reproducibility. We conclude the review with future developments and perspectives.

Special Issue in "Nanomaterials and Their Applications in Sensing and Biosensing"

The identification of the target molecule is required for rapid and reliable clinical diagnosis and disease monitoring [...].