Biomimetic Nanopillar-Based Biosensor for Label-Free Detection of Influenza A Virus

Functionalized gold nanoflowers on carbon screen-printed electrodes: an electrochemical platform for biosensing hemagglutinin protein of influenza A H1N1 virus

An electrochemical biosensor based on modified carbon screen-printed electrodes was developed for the detection of hemagglutinin of influenza A H1N1 virus (H1). Gold nanoflowers were electrodeposited on the electrode to increase conductivity and surface area. The electrochemical signal was amplified by functionalization of the gold nanoflowers with 4-aminothiophenol, which resulted in a 100-fold decrease of the charge transfer resistance due to a tunneling effect. Subsequently, monoclonal antibodies against H1 were immobilized on the surface via covalent amide bond formation, followed by blocking with bovine serum albumin to minimize nonspecific hydrophobic binding. The electrodes were characterized by cyclic voltammetry and electrochemical impedance spectroscopy experiments in the presence of [Fe(CN)6]3-/4-. Differential pulse voltammetry was used to measure the change in current across the electrode as a function of H1 concentration. This was performed on a series of samples of artificial saliva containing H1 protein in a clinically relevant concentration range. In these experiments, the biosensor showed a limit of detection of 19 pg/mL. Finally, the biosensor platform was coupled to an automated microfluidics system, and no significant decrease of the electrochemical signal was observed.

Realizing Square-Ordered Nanopillars with a 0.1-Tera-Density through a Superimposed Masking Strategy for Advanced Surface-Enhanced Raman Spectroscopy

Despite widespread interest in nanoscale pillar structures for various optical devices, including solar cells, photonic crystal lasers, and sensors, the critical challenges for mass production are the high equipment costs and limited scalability of traditional manufacturing methods. To overcome these hurdles, this study develops a simple and highly scalable etch-mask superposition technique based on thermally assisted nanotransfer printing (T-nTP) of Cr line patterns. The orthogonal superposition of linear Cr mask patterns creates double-height cross-point arrays that effectively and selectively protect the underlying SiO2 during subsequent reactive ion etching. This process generates highly uniform nanoscale pillar arrays with an extremely high density of 0.1 tera-pillars per square inch, eliminating the need for high-cost patterning platforms. As an exemplary application, we demonstrate the use of these perfectly ordered nanopillar arrays as high-performance surface-enhanced Raman scattering (SERS) sensors through the deposition of noble metal films on the nanopillar surface. These nanopillars enable exceptionally uniform SERS intensity with spot variations of less than 7% in methylene blue (MB) measurements. Additionally, they exhibit sensitive detections and accurate quantification for thiabendazole (TBZ) at concentrations as low as 10-8 M, along with multicycle reusability without noticeable degradation, owing to the outstanding robustness of the SiO2 nanopillars.

Detection strategies of infectious diseases via peptide-based electrochemical biosensors

Infectious diseases have threatened human life for as long as humankind has existed. One of the most crucial aspects of fighting against these infections is diagnosis to prevent disease spread. However, traditional diagnostic methods prove insufficient and time-consuming in the face of a pandemic. Therefore, studies focusing on detecting viruses causing these diseases have increased, with a particular emphasis on developing rapid, accurate, specific, user-friendly, and portable electrochemical biosensor systems. Peptides are used integral components in biosensor fabrication for several reasons, including various and adaptable synthesis protocols, long-term stability, and specificity. Here, we discuss peptide-based electrochemical biosensor systems that have been developed over the last decade for the detection of infectious diseases. In contrast to other reports on peptide-based biosensors, we have emphasized the following points i) the synthesis methods of peptides for biosensor applications, ii) biosensor fabrication approaches of peptide-based electrochemical biosensor systems, iii) the comparison of electrochemical biosensors with other peptide-based biosensor systems and the advantages and limitations of electrochemical biosensors, iv) the pros and cons of peptides compared to other biorecognition molecules in the detection of infectious diseases, v) different perspectives for future studies with the shortcomings of the systems developed in the past decade.

Infrared Spectroscopy of Live Cells Using High-Aspect-Ratio Metal-on-Dielectric Metasurfaces

Fourier transform infrared (FTIR) spectroscopy is widely used for molecular analysis. However, for the materials situated in an aqueous environment, a precondition for live biological objects such as cells, transmission-based FTIR is prevented by strong water absorption of mid-infrared (MIR) light. Reflection-based cellular assays using internal reflection elements (IREs) such as high-index prisms or flat plasmonic metasurfaces mitigate these issues but suffer from a shallow probing volume localized near the plasma membrane. Inspired by the recent introduction of high-aspect-ratio nanostructures as a novel platform for manipulating cellular behavior, we demonstrate that the integration of plasmonic metasurfaces with tall dielectric nanostructures dramatically enhances the sensing capabilities of FTIR spectroscopy. We also demonstrate the ability of a metal-on-dielectric metasurface to transduce intracellular processes, such as protein translocation to high-curvature membrane regions during cell adhesion, into interpretable spectral signatures of the reflected light.

Nanomaterial-based sensors for microbe detection: a review

Airborne microorganisms pose a significant health threat, causing various illnesses. Traditional detection methods are often slow and complex. This review highlights the potential of nanomaterial-based biosensors, particularly colorimetric sensors, for rapid and on-site detection of airborne microbes. Colorimetric sensors offer real-time visual detection without complex instrumentation. We explore the integration of these sensors with Lab-on-a-Chip technology using PDMS microfluidics. This review also proposes a novel PDMS-based colorimetric biosensor for real-time detection of airborne microbes. The sensor utilizes a color change phenomenon easily observable with the naked eye, simplifying analysis and potentially enabling point-of-care applications.

Engineering the Cellular Microenvironment: Integrating Three-Dimensional Nontopographical and Two-Dimensional Biochemical Cues for Precise Control of Cellular Behavior

The development of biomaterials capable of regulating cellular processes and guiding cell fate decisions has broad implications in tissue engineering, regenerative medicine, and cell-based assays for drug development and disease modeling. Recent studies have shown that three-dimensional (3D) nanoscale physical cues such as nanotopography can modulate various cellular processes like adhesion and endocytosis by inducing nanoscale curvature on the plasma and nuclear membranes. Two-dimensional (2D) biochemical cues such as protein micropatterns can also regulate cell function and fate by controlling cellular geometries. Development of biomaterials with precise control over nanoscale physical and biochemical cues can significantly influence programming cell function and fate. In this study, we utilized a laser-assisted micropatterning technique to manipulate the 2D architectures of cells on 3D nanopillar platforms. We performed a comprehensive analysis of cellular and nuclear morphology and deformation on both nanopillar and flat substrates. Our findings demonstrate the precise engineering of single cell architectures through 2D micropatterning on nanopillar platforms. We show that the coupling between the nuclear and cell shape is disrupted on nanopillar surfaces compared to flat surfaces. Furthermore, our results suggest that cell elongation on nanopillars enhances nanopillar-induced endocytosis. We believe our platform serves as a versatile tool for further explorations into programming cell function and fate through combined physical cues that create nanoscale curvature on cell membranes and biochemical cues that control the geometry of the cell.

Recent Advances in Biosensor Development for the Detection of Viral Particles in Foods: A Comprehensive Review

Viral foodborne diseases cause serious harm to human health and the economy. Rapid, accurate, and convenient approaches for detecting foodborne viruses are crucial for preventing diseases. Biosensors integrating electrochemical and optical properties of nanomaterials have emerged as effective tools for the detection of viruses in foods. However, they still face several challenges, including substantial sample preparation and relatively poor sensitivity due to complex food matrices, which limit their field applications. Hence, the purpose of this review is to provide an overview of recent advances in biosensing techniques, including electrochemical, SERS-based, and colorimetric biosensors, for detecting viral particles in food samples, with emerging techniques for extraction/concentration of virus particles from food samples. Moreover, the principle, design, and advantages/disadvantages of each biosensing method are comprehensively described. This review covers the recent development of rapid and sensitive biosensors that can be used as new standards for monitoring food safety and food quality in the food industry.

Hybrid CRISPR/Cas protein for one-pot detection of DNA and RNA

Clustered regularly interspaced short palindromic repeats (CRISPR)-based diagnostics have emerged as next-generation molecular diagnostics. In CRISPR-based diagnostics, Cas12 and Cas13 proteins have been widely employed to detect DNA and RNA, respectively. Herein, we developed a novel hybrid Cas protein capable of detecting universal nucleic acids (DNA and RNA). The CRISPR/hybrid Cas system simultaneously recognizes both DNA and RNA, enabling the dual detection of pathogenic viruses in a single tube. Using wild-type (WT) and N501Y mutant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as detection models, we successfully detected both virus strains with a detection limit of 10 viral copies per reaction without cross-reactivity. Furthermore, it is demonstrated the detection of WT SARS-CoV-2 and N501Y mutant variants in clinical samples by using the CRISPR/hybrid Cas system. The hybrid Cas protein is expected to be utilized in a molecular diagnostic method for infectious diseases, tissue and liquid biopsies, and other nucleic acid biomarkers.

Highly Adsorptive Au-TiO2 Nanocomposites for the SERS Face Mask Allow the Machine-Learning-Based Quantitative Assay of SARS-CoV-2 in Artificial Breath Aerosols

Human respiratory aerosols contain diverse potential biomarkers for early disease diagnosis. Here, we report the direct and label-free detection of SARS-CoV-2 in respiratory aerosols using a highly adsorptive Au-TiO₂ nanocomposite SERS face mask and an ablation-assisted autoencoder. The Au-TiO₂ SERS face mask continuously preconcentrates and efficiently captures the oronasal aerosols, which substantially enhances the SERS signal intensities by 47% compared to simple Au nanoislands. The ultrasensitive Au-TiO₂ nanocomposites also demonstrate the successful detection of SARS-CoV-2 spike proteins in artificial respiratory aerosols at a 100 pM concentration level. The deep learning-based autoencoder, followed by the partial ablation of nondiscriminant SERS features of spike proteins, allows a quantitative assay of the 10¹-10⁴ pfu/mL SARS-CoV-2 lysates (comparable to 19-29 PCR cyclic threshold from COVID-19 patients) in aerosols with an accuracy of over 98%. The Au-TiO₂ SERS face mask provides a platform for breath biopsy for the detection of various biomarkers in respiratory aerosols.

Emerging 0D, 1D, 2D, and 3D nanostructures for efficient point-of-care biosensing

The recent COVID-19 infection outbreak has raised the demand for rapid, highly sensitive POC biosensing technology for intelligent health and wellness. In this direction, efforts are being made to explore high-performance nano-systems for developing novel sensing technologies capable of functioning at point-of-care (POC) applications for quick diagnosis, data acquisition, and disease management. A combination of nanostructures [i.e., 0D (nanoparticles & quantum dots), 1D (nanorods, nanofibers, nanopillars, & nanowires), 2D (nanosheets, nanoplates, nanopores) & 3D nanomaterials (nanocomposites and complex hierarchical structures)], biosensing prototype, and micro-electronics makes biosensing suitable for early diagnosis, detection & prevention of life-threatening diseases. However, a knowledge gap associated with the potential of 0D, 1D, 2D, and 3D nanostructures for the design and development of efficient POC sensing is yet to be explored carefully and critically. With this focus, this review highlights the latest engineered 0D, 1D, 2D, and 3D nanomaterials for developing next-generation miniaturized, portable POC biosensors development to achieve high sensitivity with potential integration with the internet of medical things (IoMT, for miniaturization and data collection, security, and sharing), artificial intelligence (AI, for desired analytics), etc. for better diagnosis and disease management at the personalized level.

Surface modified chitosan-silica nanocomposite porous thin film based multi-parametric optical glucose sensor

In this work, a multi-parametric optical sensor based on chitosan-silica nanocomposite (CSNC) porous thin film has been developed for effective detection of glucose in pathological range. The CSNC films were surface functionalized with Glucose Oxidase enzyme via Glutaraldehyde crosslinking chains for better attachment of enzyme molecules on thin film surface. FESEM and FTIR were performed for morphological and compositional characterisation of the composite films. Five interlinked optical parameters, i.e., transmittance (T), reflectance (R), internal scattering (IS), surface scattering (SS) and output power (OP) were measured simultaneously using image processing environment for cost efficiency of the system. Effect of surface functionalization on individual parameter response was studied. It was observed that without surface functionalization only two parameters change significantly, while surface functionalization enables all five parameters. For lower and higher glucose concentration (< 17 mM and > 17 mM), IS and SS were found to be maximum sensitive among the five parameters, respectively. Maximum sensitivity of 1.2 mM-1 in IS and 1 mM-1 in SS were observed for surface functionalized samples. The sensor showed good sensitivity, selectivity and reproducibility in the dynamic range of 3-30 mM and LOD of the sensor was found to be 0.76 mM. CSNC sensors were found suitable for single-time use and as mass production is possible with little amount of composite solution (250 sensors with just 10-ml composite solution), the sensor fabrication method is very much cost efficient. Image processing-based multi-parametric sensing is a novel field itself and detailed study of surface modified CSNC glucose sensors utilizing such sensing system is a unique work having potential to significantly contribute in the field of multi-parametric label-free optical biosensor research.

Nanomaterials for virus sensing and tracking

The effect of the on-going COVID-19 pandemic on global healthcare systems has underlined the importance of timely and cost-effective point-of-care diagnosis of viruses. The need for ultrasensitive easy-to-use platforms has culminated in an increased interest for rapid response equipment-free alternatives to conventional diagnostic methods such as polymerase chain reaction, western-blot assay, etc. Furthermore, the poor stability and the bleaching behavior of several contemporary fluorescent reporters is a major obstacle in understanding the mechanism of viral infection thus retarding drug screening and development. Owing to their extraordinary surface-to-volume ratio as well as their quantum confinement and charge transfer properties, nanomaterials are desirable additives to sensing and imaging systems to amplify their signal response as well as temporal resolution. Their large surface area promotes biomolecular integration as well as efficacious signal transduction. Due to their hole mobility, photostability, resistance to photobleaching, and intense brightness, nanomaterials have a considerable edge over organic dyes for single virus tracking. This paper reviews the state-of-the-art of combining carbon-allotrope, inorganic and organic-based nanomaterials with virus sensing and tracking methods, starting with the impact of human pathogenic viruses on the society. We address how different nanomaterials can be used in various virus sensing platforms (e.g. lab-on-a-chip, paper, and smartphone-based point-of-care systems) as well as in virus tracking applications. We discuss the enormous potential for the use of nanomaterials as simple, versatile, and affordable tools for detecting and tracing viruses infectious to humans, animals, plants as well as bacteria. We present latest examples in this direction by emphasizing major advantages and limitations.

Use of Nanomaterials for Diagnosis and Treatment: The Advancement of Next-Generation Antiviral Therapy

Globally, viral illness propagation is the leading cause of morbidity and death, causing wreaking havoc on socioeconomic development and health care systems. The rise of infected individuals has outpaced the existing critical care facilities. Early and sophisticated methods are desperately required in this respect to halt the spread of the infection. Therefore, early detection of infectious agents and an early treatment approach may help minimize viral outbreaks. Conventional point-of-care diagnostic techniques such as computed tomography scan, quantitative real time polymerase chain reaction (qRT-PCR), X-ray, and immunoassay are still deemed valuable. However, the labor demanding, low sensitivity, and complex infrastructure needed for these methods preclude their use in distant areas. Nanotechnology has emerged as a potentially transformative technology due to its promise as an effective theranostic platform for diagnosing and treating viral infection, circumventing the limits of traditional techniques. Their unique physical and chemical characteristics make nanoparticles (NPs) advantageous for drug delivery platforms due to their size, encapsulation efficiency, improved bioavailability, effectiveness, immunogenicity, and antiviral response. This study discusses the recent research on nanotechnology-based treatments designed to combat new viruses.

Veni, Vidi, Vici: Immobilized Peptide-Based Conjugates as Tools for Capture, Analysis, and Transformation

Analysis of peptide biomarkers of pathological states of the organism is often a serious challenge, due to a very complex composition of the cell and insufficient sensitivity of the current analytical methods (including mass spectrometry). One of the possible ways to overcome this problem is sample enrichment by capturing the selected components using a specific solid support. Another option is increasing the detectability of the desired compound by its selective tagging. Appropriately modified and immobilized peptides can be used for these purposes. In addition, they find application in studying the specificity and activity of proteolytic enzymes. Immobilized heterocyclic peptide conjugates may serve as metal ligands, to form complexes used as catalysts or analytical markers. In this review, we describe various applications of immobilized peptides, including selective capturing of cysteine-containing peptides, tagging of the carbonyl compounds to increase the sensitivity of their detection, enrichment of biological samples in deoxyfructosylated peptides, and fishing out of tyrosine–containing peptides by the formation of azo bond. Moreover, the use of the one-bead-one-compound peptide library for the analysis of substrate specificity and activity of caspases is described. Furthermore, the evolution of immobilization from the solid support used in peptide synthesis to nanocarriers is presented. Taken together, the examples presented here demonstrate immobilized peptides as a multifunctional tool, which can be successfully used to solve multiple analytical problems.