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The conventional tissue biopsy method yields isolated snapshots of a narrow region. Therefore, it cannot facilitate comprehensive disease characterization and monitoring. Recently, the detection of tumor-derived components in body fluidsa practice known as liquid biopsyhas attracted increased attention from the biochemical research and clinical application viewpoints. In this vein, surface-enhanced Raman scattering (SERS) has been identified as one of the most powerful liquidbiopsy analysis techniques, owing to its high sensitivity and specificity. Moreover, it affords high-capacity spectral multiplexing for simultaneous target detection and a unique ability to obtain intrinsic biomolecule-fingerprint spectra. This paper presents the fabrication of silver nanosnowflakes (SNSFs) using the polyol method and their subsequent dropping onto a hydrophobic filter paper. The SERS substrate, which comprises the SNSFs and hydrophobic filter paper, facilitates the simultaneous detection of creatinine and cortisol in human sweat using a hand-held Raman spectrometer. The proposed SERS system affords Raman spectrometry to be performed on small sample volumes (2 μL) to identify the normal and at-risk creatinine and cortisol groups.

Hydrogels containing colorimetric nanoparticles have been used for ion sensing, glucose detection, and microbial metabolite analyses. In particular, the rapid chemical reaction owing to both the hydrogel form of water retention and the sensitive color change of nanoparticles enables the rapid detection of target substances. Despite this advantage, the poor dispersibility of nanoparticles and the mechanical strength of nanoparticle–hydrogel complexes have limited their application. In this study, we demonstrate a milliliter agarose gel containing homogeneously synthesized polyaniline nanoparticles (PAni-NPs), referred to as PAni-NP–hydrogel complexes (PNHCs). To fabricate the optimal PNHC, we tested various pH solvents based on distilled water and phosphate-buffered saline and studied the colorimetric response of the PNHC with thickness. The colorimetric response of the prepared PNHC to the changes in the pH of the solution demonstrated excellent linearity, suggesting the possibility of using PNHC as a pH sensor. In addition, it was verified that the PNHC could detect minute pH changes caused by the cancer cell metabolites without cytotoxicity. Furthermore, the PNHC can be stably maintained outside water for approximately 12 h without deformation, indicating that it can be used as a disposable patch-type wearable biosensing platform.

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The coronavirus disease (COVID-19) pandemic has spread to nearly every corner of the globe, significantly impacting economies and societies. Despite the advances in detection technologies for targeting viral pathogens, all countries are facing an unprecedented need for achieving biosensor technologies in a rapid, sensitive, selective, and reliable way to deal with global and urgent problems. Till date, reverse transcription-polymerase chain reaction (RT-PCR) is the gold standard method for COVID-19 diagnosis. However, it requires complex facilities and elaborate training, which is hampered by limited testing capacity and delayed results. Herein, we review state-of-the-art research on point-of-care biosensors for early severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection. We included a general description of nanotechnological techniques for developing biosensors, along with the latest research on various biosensors for SARS-CoV-2 detection, and a summary of their limitations for practical use. Finally, we discuss the future perspectives and directions. This critical review offers insight into the biosensor community in furthering the present research, which may streamline attrition problems for rapid and large-scale SARS-CoV-2 screening.

Metaphase chromosomes in which both polynucleotides and proteins are condensed with hierarchies are closely related to life phenomena such as cell division, cancer development, and cellular senescence. Nevertheless, their nature...

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Polyaniline nanoskein (PANS), which have polyaniline nanofibers, was developed. PANS was formulated via sequential extracting, heating, and swelling processes. The compositions of PANS have been analyzed using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and Brunauer–Emmett–Teller analysis, and the results of which indicate that PANS is composed of solely organic materials. Moreover, PANS has been shown convertible absorbance characteristics according to surrounding acidic environments, and using these characteristics, the possibility of PANS for sensing of surrounding redox state changes is presented.