A Miniaturized, Battery-Free, Wireless Wound Monitor That Predicts Wound Closure Rate Early.

Diabetic foot ulcers are chronic wounds that affect millions and increase the risk of amputation and mortality, highlighting the critical need for their early detection. Recent demonstrations of wearable sensors enable real-time wound assessment, but they rely on bulky electronics, making them difficult to interface with wounds. Herein, a miniaturized, wireless, battery-free wound monitor that measures lactate in real-time and seamlessly integrates with bandages for conformal attachment to the wound bed is introduced. Lactate is selected due to its multifaceted role in initiating healing. Studies in healthy and diabetic mice reveal distinct lactate profiles for normal and impaired healing wounds. A mathematical model based on the sensor data predicts wound closure rate within the first 3 days post-injury with ≈76% accuracy, which increases to ≈83% when pH is included. These studies underscore the significance of monitoring biomarkers during the inflammation phase, which can offer several benefits, including short-term use of wound monitors and their easy removal, resulting in lower risks of injury and infection at the wound site. Improvements in prediction accuracy can be achieved by designing mathematical models that build on multiple wound parameters such as pro-inflammatory and metabolic markers. Achieving this goal will require designing multi-analyte wound monitors.

Development of core-shell magnetic molecularly imprinted polymer-based electrochemical sensor for sensitive and selective detection of ezetimibe.

A sensitive electrochemical molecularly imprinted polymer (MIP) sensor was fabricated for detection of ezetimibe (Eze) as an effective cholesterol absorption inhibitor on the surface of a screen-printed carbon electrode based on a magnetic nanoparticle decorated with MIP (Fe3O4@MIP). Placing the magnetic nanoparticle inside the MIP increases the biocompatibility, surface-to-volume ratio, and sensitivity of the sensor. Methacrylic acid (MAA) was used as a monomer, ethylene glycol dimethacrylate (EGDMA) as a cross-linker, and Eze as a template. The fabricated Fe3O4@MIP was characterized using Fourier-transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Detection of Eze was achieved by differential pulse voltammetry. Using this sensor, Eze can be sensitively detected in the range of 1.0 nM-10 µM and detection limit of 0.7 nM. In addition, we have shown that the proposed sensor successfully detects different concentrations of Eze in human serum samples and thus proves its practical application.

Dual rolling circle amplification-enabled ultrasensitive multiplex detection of exosome biomarkers using electrochemical aptasensors.

Breast cancer is one of the leading causes of cancer-related death. An effective diagnostic system that enables early cancer detection is required for timely diagnosis and better treatment outcomes. Here, we developed an ultrasensitive electrochemical aptasensor for the multiplex detection of exosome biomarkers based on the electrochemical signals of metal ions. Specifically, a screen-printed carbon electrode (SPCE) was first modified with a multi-walled carbon nanotube (MWCNT), ionic liquid (IL), and chitosan (CHT) composite, and then gold nanoparticles (GNPs) were deposited via electrodeposition (GNPs/MWCNT-IL-CHT). To capture target exosomes, an aptamer specific for CD63, the universal exosome surface protein, was immobilized on the GNPs/MWCNT-IL-CHT/SPCE. When EpCAM or HER-2 positive exosomes were present in the sample, they could bind to EpCAM or HER-2 aptamers with primer sequences that acted as a rolling circle amplification reaction initiator, thereby generating numerous poly-guanine and poly-thymine repeats of a metal ion binding sequence, which produced strong electrochemical signals upon complexation with copper and lead ions. Using the proposed, multiplex exosome analysis system, EpCAM- and HER-2-positive exosomes were simultaneously detected with high specificity and a detection limit of 1 particle mL-1. In addition, its clinical applicability was validated via spike-and-recovery experiments using human serum samples.

Pyrophosphate-Enhanced Oxidase Activity of Cerium Oxide Nanoparticles for Colorimetric Detection of Nucleic Acids.

In recent years, cerium oxide (CeO2) nanoparticles (NPs) have drawn significant attention owing to their intrinsic enzyme mimetic properties, which make them powerful tools for biomolecular detection. In this work, we evaluated the effect of pyrophosphate (PPi) on the oxidase activity of CeO2 NPs. The presence of PPi was found to enhance the oxidase activity of CeO2 NPs, with enhanced colorimetric signals. This particular effect was then used for the colorimetric detection of target nucleic acids. Overall, the PPi-enhanced colorimetric signals of CeO2 NPs oxidase activity were suppressed by the presence of the target nucleic acids. Compared with previous studies using CeO2 NPs only, our proposed system significantly improved the signal change (ca. 200%), leading to more sensitive and reproducible colorimetric analysis of target nucleic acids. As a proof-of-concept study, the proposed system was successfully applied to the highly selective and sensitive detection of polymerase chain reaction products derived from Klebsiella pneumoniae. Our findings will benefit the rapid detection of nucleic acid biomarkers (e.g., pathogenic bacterial DNA or RNA) in point-of-care settings.

Construction of a highly sensitive signal-on aptasensor based on gold nanoparticles/functionalized silica nanoparticles for selective detection of tryptophan.

In this work, a highly sensitive, low-cost, and label-free aptasensor based on signal-on mechanisms of response was developed by immobilizing the aptamer on gold nanoparticles (AuNPs)/amine-functionalized silica nanoparticle (FSN)/screen-printed electrode (SPE) surface for highly selective electrochemical detection of tryptophan (Trp). The hemin (Hem), which interacted with the guanine bases of the aptamer, worked as a redox indicator to generate a readable electrochemical signal. The changes in the charge transfer resistance have been monitored using the voltammetry and electrochemical impedance spectroscopic (EIS) techniques. The peak current of Hem linearly increased with increasing concentration of Trp, in differential pulse voltammetry, from 0.06 to 250 nM with a detection limit of 0.026 nM. Also, the results obtained from EIS studies showed that the Trp was detected sensitively with the fabricated aptasensor in the range of 0.06-250 nM. The detection limit is 0.01 nM, much lower than that obtained by most of the reported electrochemical methods. The usage of aptamer as a recognition layer led to a sensor with high affinity for Trp, compared with control amino acids of tyrosine, histidine, arginine, lysine, valine, and methionine. The usability of the aptasensor was successfully evaluated by the determination of Trp in a human blood serum sample. Thus, the sensor could provide a promising plan for the construction of aptasensors. Graphical abstract Schematic outline the principle for tryptophan aptasensing.

Design an aptasensor based on structure-switching aptamer on dendritic gold nanostructures/Fe3O4@SiO2/DABCO modified screen printed electrode for highly selective detection of epirubicin.

The present work describes a label free electrochemical aptasensor for selective detection of epirubicin. In this project, 5'-thiole terminated aptamer was self-assembled on carbon screen printed electrode, which modified with electrodeposited gold nanoparticles on magnetic double-charged diazoniabicyclo [2.2.2] octane dichloride silica hybrid (Fe3O4@SiO2/DABCO) by Au-S bond. The interactions of epirubicin with aptamer on the AuNPs/Fe3O4@SiO2/DABCO/SPE have been studied by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy. Under optimized conditions, the peak current of epirubicin increased linearly with increasing epirubicin concentration, due to the switching in the aptamer conformation and formation of aptamer- epirubicin complex instead of aptamer on the modified electrode surface. The Apt/AuNPs/Fe3O4@SiO2/DABCO/SPE is sensitive, selective and has two linear range from 0.07µM to 1.0µM and 1.0µM to 21.0µM with a detection limit of 0.04µM. The applicability of the aptasensor was successfully assessed by determination of epirubicin in a human blood serum sample.

Ultrasensitive electrochemical aptasensor based on sandwich architecture for selective label-free detection of colorectal cancer (CT26) cells.

Colorectal cancer is one of the most common cancers in the world and has no effective treatment. Therefore, development of new methods for early diagnosis is instantly required. Biological recognition probes such as synthetic receptor and aptamer is one of the candidate recognition layers to detect important biomolecules. In this work, an electrochemical aptasensor was developed by fabricating an aptamer-cell-aptamer sandwich architecture on an SBA-15-3-aminopropyltriethoxysilane (SBA-15-pr-NH2) and Au nanoparticles (AuNPs) modified graphite screen printed electrode (GSPE) surface for the selective, label-free detection of CT26 cancer cells. Based on the incubation of the thiolated aptamer with CT26 cells, the electron-transfer resistance of Fe (CN)63-/4- redox couple increased considerably on the aptasensor surface. The results obtained from cyclic voltammetry and electrochemical impedance spectroscopy studies showed that the fabricated aptasensor can specifically identify CT26 cells in the concentration ranges of 10-1.0×105cells/mL and 1.0×105-6.0×106 cells/mL, respectively, with a detection limit of 2cells/mL. Applying the thiol terminated aptamer (5TR1) as a recognition layer led to a sensor with high affinity for CT26 cancer cells, compared to control cancer cells of AGS cells, VERO Cells, PC3 cells and SKOV-3 cells. Therefore a simple, rapid, label free, inexpensive, excellent, sensitive and selective electrochemical aptasensor based on sandwich architecture was developed for detection of CT26 Cells.

Interaction of sulfadiazine with DNA on a MWCNT modified glassy carbon electrode: determination of DNA.

The interactions of sulfadiazine (SD), an antimicrobial drug, with double-stranded calf thymus DNA on the multi-walled carbon nanotubes modified glassy carbon electrode (MWCNT-GCE) have been studied by cyclic voltammetry and UV-vis spectroscopy. In the presence of DNA, the oxidation peak current of SD decreases and the peak potential shifts to a positive potential which indicates the interaction of SD with DNA. The binding of SD with DNA shows both electrostatic and intercalative modes. The binding of SD with DNA, when analyzed in terms of the cooperative Hill model, yields the binding constant, K(a)=2.87 × 10(3)M(-1) and a Hill coefficient m=1.9 in Britton-Robinson (B-R) buffer solution, pH=6.5. This electrochemical method was further applied to the determination of DNA. Under the selected conditions, two linear calibration curves for DNA detection were obtained in the concentration ranges from 0.03 to 0.13 µgmL(-1) and 0.60-3.50 µgmL(-1) with detection limit 0.03 µgmL(-1). The method was also applied to the determination of DNA in human blood plasma sample.