Molecular Imprinted Polymers on Microneedle Arrays for Point of Care Transdermal Sampling and Sensing of Inflammatory Biomarkers.

The skin interstitial fluid (ISF) contains biomarkers that complement other biofluids such as blood, sweat, saliva, and urine. It can be sampled in a minimally invasive manner and used either for point of care testing or real time, continuous monitoring of analytes, the latter using microneedle arrays. The analytes present in the skin ISF are indicative of both systemic and local (i.e., skin) physiology. In this paper, we describe combining microneedle technology with molecularly imprinted polymers to demonstrate the potential of transdermal electrochemical sensing. The molecularly imprinted polymer employed here is easy to produce; it can be thought of as plastic antibody. Its synthesis is scalable, and the resulting sensor has a short measurement time (6 min), with high accuracy and a low limit of detection. It provides the requisite specificity to detect the proinflammatory cytokine IL-6. IL-6 is present in the skin ISF with other cytokines and is implicated in many clinical states including neurodegenerative diseases and fatal pneumonia from SARSCoV 2. The ability to mass produce microneedle arrays and plastic antibodies will allow for low-cost transdermal sensing devices. The transdermal sensors were able to detect IL-6 at concentrations as low as 1 pg/mL in artificial skin ISF, indicating its utility for routine point of care, bloodless measurements in simpler settings, worldwide.

Development of colorimetric cellulose-based test-strip for the rapid detection of antibodies against SARS-CoV2 virus.

Given the pandemic situation, there is an urgent need for an accurate test to monitor antibodies anti-SARS-CoV-2, providing crucial epidemiological and clinical information to monitor the evolution of coronavirus disease in 2019 (COVID-19) and to stratify the immunized and asymptomatic population. Therefore, this paper describes a new cellulose-based test strip for rapid and cost-effective quantitative detection of antibodies to SARS-CoV2 virus by colorimetric transduction. For this purpose, Whatman paper was chemically modified with sodium metaperiodate to introduce aldehyde groups on its surface. Subsequently, the spike protein of the virus is covalently bound by forming an imine group. The chemical control of cellulose paper modification was evaluated by Fourier transform infrared spectroscopy, thermogravimetry and contact angle analysis. Colorimetric detection of the antibodies was performed by a conventional staining method using Ponceau S solution as the dye. Color analysis was performed after image acquisition with a smartphone using Image J software. The color intensity varied linearly with the logarithm of the anti-S concentration (from 10 ng/mL to 1 µg/mL) in 500-fold diluted serum samples when plotted against the green coordinate extracted from digital images. The test strip was selective in the presence of nucleocapsid antibodies, urea, glucose, and bovine serum albumin with less than 15% interference, and detection of antibodies in human serum was successfully performed. Overall, this is a simple and affordable design that can be readily used for mass population screening and does not require sophisticated equipment or qualified personnel. Supplementary Information: The online version contains supplementary material available at 10.1007/s10570-022-04808-y.

Colorimetric cellulose-based test-strip for rapid detection of amyloid ß-42.

An innovative sensing assay is described for point-of-care (PoC) quantification of a biomarker of Alzheimer's disease, amyloid ß-42 (Aß-42). This device is based on a cellulose paper-dye test strip platform in which the corresponding detection layer is integrated by applying a molecularly imprinted polymer (MIP) to the cellulose paper surface. Briefly, the cellulose paper is chemically modified with a silane to subsequently apply the MIP detection layer. The imprinting process is confirmed by the parallel preparation of a control material, namely a non-imprinted polymer (NIP). The chemical changes of the surface were evaluated by Fourier transform infrared spectroscopy (FTIR), contact angle, and thermogravimetric analysis (TG). Proteins and peptides can be quantified by conventional staining methods. For this purpose, Coomassie blue (CB) was used as a staining dye for the detection and quantification of Aß-42. Quantitative determination is made possible by taking a photograph and applying an appropriate mathematical treatment to the color coordinates provided by the ImageJ program. The MIP shows a linear range between 1.0 ng/mL and 10 µg/mL and a detection limit of 0.71 ng/mL. Overall, this cellulose-based assay is suitable for the detection of peptides or proteins in a sample by visual comparison of color change. The test strip provides a simple, instrument-free, and cost-effective method with high chemical stability, capable of detecting very small amounts of peptides or proteins in a sample, and can be used for the detection of any (bio)molecule of interest.