Rapid Point-of-Care Electrochemical Sensor for the Detection of Cancer Tn Antigen Carbohydrate in Whole Unprocessed Blood

Lubricin (PRG4) antifouling coating enables the development of an immunosensor for the detection of nerve growth factor in cell culture media

Growth factors (GFs) are the unique signaling molecules that enable constant communication and feedback between cells, modulating cell behavior and maintaining the structure and function of tissues. Traditional methods to detect and quantify GFs, such as ELISA, offer high specificity but are usually costly, present lower limits of detection, typically require sample processing, and are time-consuming. Electrochemical sensing emerges as a promising alternative due to their rapid responses and easy operation; however, they are prone to biofouling when challenged in complex biological environments. This study introduces an antifouling agent, lubricin (LUB), into an electrochemical immunosensor for the detection nerve growth factor (NGF). Through the combination of a specific NGF antibody with LUB, the developed sensor presents a great sensitivity, achieving a limit detection of 0.59 ng mL-1 for the target NGF. Our results show that the proposed sensing configuration can detect NGF directly in unprocessed and undiluted cell culture media with much faster analytical responses when compared to ELISA.

Review of advances in glycan analysis on exosomes, cancer cells, and circulating cancer-derived glycoproteins with an emphasis on electrochemistry

Glycosylation, the intricate process of adding carbohydrate motifs to proteins, lipids, and exosomes on the cell surface, is crucial for both physiological and pathological mechanisms. Alterations in glycans significantly affect cancer cell metastasis by mediating cell-cell and cell-matrix interactions. The subtle changes in glycosylation during malignant transformations highlight the importance of analyzing cell and exosome surface glycosylation for prognostic and early treatment strategies in cancer. This review focuses on recent advancements in sensors for detecting surface glycans on cancer cells, exosomes, and circulating cancer-derived glycoproteins. Among various methods, electrochemical biosensors stand out as a promising tool, offering rapid and cost-effective glycan detection. These devices detect glycan interactions by measuring changes in electrical signals resulting from specific binding events. Techniques such as differential pulse voltammetry, impedance spectroscopy, and chrono amperometry are commonly employed for glycan detection using electrochemical biosensors. Researchers are exploring novel electrode materials and surface functionalization strategies to enhance sensor performance. Notably, selective binding probes such as lectins, aptamers, antibodies, and boronic acids are discussed, with lectins being the most prevalent for specific glycan analysis. By highlighting the significance of electrochemical techniques, emphasizing the role of selective binding probes, integrating microfluidics and miniaturized devices could lead to point-of-care applications for cancer diagnosis and monitoring. This review aims to provide valuable insights for researchers and clinicians working in the field of cancer glycomics.

Self-Assembled Lubricin (PRG-4)-Based Biomimetic Surface-Enhanced Raman Scattering Sensor for Direct Droplet Detection of Melamine in Undiluted Milk

Surface-enhanced Raman scattering (SERS) is a powerful optical sensing platform that amplifies the target signals by Raman scattering. Despite SERS enabling a meager detection limit, even at the single-molecule level, SERS also tends to equally enhance unwanted molecules due to the non-specific binding of noise molecules in clinical samples, which complicates its use in complex samples such as bodily fluids, environmental water, or food matrices. To address this, we developed a novel non-fouling biomimetic SERS sensor by self-assembling an anti-adhesive, anti-fouling, and size-selective Lubricin (LUB) coating on gold nanoparticle (AuNP) functionalized glass slide surfaces via a simple drop-casting method. Compared to a conventional AuNPs-SERS substrate, the biomimetic SERS meets the requirements of simple preparation and enables direct droplet detection without any sample pre-treatment. Atomic force microscopy was used to confirm the self-assembled Lubricin coating on the AuNP surface, acting as an anti-fouling and size-selective protection layer. A series of Raman spectra were collected using melamine as the target analyte, which was spiked into 150 mM NaCl solution or undiluted milk. It was demonstrated that the LUB coating effectively prevents the detrimental fouling generated by the proteins and fats in milk, ensuring the clear detection of melamine. Our sensor showed high selectivity and could detect melamine in milk at concentrations as low as 1 ppm. Given that the EU/US legal limit for melamine in food is 2.5 ppm, this sensor offers a promising, cost-effective solution for routine screening and has potential applications for detecting food adulteration in the food safety, environmental monitoring, aquaculture, and biomedical fields.

Highly sensitive multiplexed colorimetric lateral flow immunoassay by plasmon-controlled metal-silica isoform nanocomposites: PINs

Lateral flow assay (LFA) systems use metal nanoparticles for rapid and convenient target detection and are extensively studied for the diagnostics of various diseases. Gold nanoparticles (AuNPs) are often used as probes in LFAs, displaying a single red color. However, there is a high demand for colorimetric LFAs to detect multiple biomarkers, requiring the use of multicolored NPs. Here, we present a highly sensitive multiplexed colorimetric lateral flow immunoassay by multicolored Plasmon-controlled metal-silica Isoform Nanocomposites (PINs). We utilized the localized surface plasmon resonance effect to create multi-colored PINs by precisely adjusting the distance between the NPs on the surface of PINs through the controlled addition of reduced gold and silver precursors. Through simulations, we also confirmed that the distance between nanoparticles on the surface of PINs significantly affects the color and colorimetric signal intensity of the PINs. We achieved multicolored PINs that exhibit stronger colorimetric signals, offering a new solution for LFA detection with high sensitivity and a 33 times reduced limit of detection (LOD) while maintaining consistent size deviations within 5%. We expect that our PINs-based colorimetric LFA will facilitate the sensitive and simultaneous detection of multiple biomarkers in point-of-care testing.

Lubricin (PRG-4) anti-fouling coating for surface-enhanced Raman spectroscopy biosensing: towards a hierarchical separation system for analysis of biofluids

Surface-enhanced Raman Spectroscopy (SERS) is a powerful optical sensing technique that amplifies the signal generated by Raman scattering by many orders of magnitude. Although the extreme sensitivity of SERS enables an extremely low limit of detection, even down to single molecule levels, it is also a primary limitation of the technique due to its tendency to equally amplify 'noise' generated by non-specifically adsorbed molecules at (or near) SERS-active interfaces. Eliminating interference noise is thus critically important to SERS biosensing and typically involves onerous extraction/purification/washing procedures and/or heavy dilution of biofluid samples. Consequently, direct analysis within biofluid samples or in vivo environments is practically impossible. In this study, an anti-fouling coating of recombinant human Lubricin (LUB) was self-assembled onto AuNP-modified glass slides via a simple drop-casting method. A series of Raman spectra were collected using rhodamine 6G (R6G) as a model analyte, which was spiked into NaCl solution or unprocessed whole blood. Likewise, we demonstrate the same sensing system for the quantitative detection of L-cysteine spiked in undiluted milk. It was demonstrated for the first time that LUB coating can mitigate the deleterious effect of fouling in a SERS sensor without compromising the detection of a target analyte, even in a highly fouling, complex medium like whole blood or milk. This feat is achieved through a molecular sieving property of LUB that separates small analytes from large fouling species directly at the sensing interface resulting in SERS spectra with low background (i.e., noise) levels and excellent analyte spectral fidelity. These findings indicate the great potential for using LUB coatings together with an analyte-selective layer to form a hierarchical separation system for SERS sensing of relevant analytes directly in complex biological media, aquaculture, food matrix or environmental samples.

Applications of Graphene in Five Senses, Nervous System, and Artificial Muscles

Graphene remains of great interest in biomedical applications because of biocompatibility. Diseases relating to human senses interfere with life satisfaction and happiness. Therefore, the restoration by artificial organs or sensory devices may bring a bright future by the recovery of senses in patients. In this review, we update the most recent progress in graphene based sensors for mimicking human senses such as artificial retina for image sensors, artificial eardrums, gas sensors, chemical sensors, and tactile sensors. The brain-like processors are discussed based on conventional transistors as well as memristor related neuromorphic computing. The brain-machine interface is introduced for providing a single pathway. Besides, the artificial muscles based on graphene are summarized in the means of actuators in order to react to the physical world. Future opportunities remain for elevating the performances of human-like sensors and their clinical applications.