Advantages of Graphene Biosensors for Human Stem Cell Therapy Potency Assays

Regenerative medicine is challenged by the need to conform to rigorous guidelines for establishing safe and effective development and translation of stem cell-based therapies. Counteracting widespread concerns regarding unproven cell therapies, stringent cell-based assays seek not only to avoid harm but also to enhance quality and efficacy. Potency indicates that the cells are functionally fit for purpose before they are administered to the patient. It is a paramount quantitative critical quality attribute serving as a decisive release criterion. Given a broad range of stem cell types and therapeutic contexts the potency assay often comprises one of the most demanding hurdles for release of a cell therapy medicinal product. With need for improved biomarker assessment and expedited measurement, recent advances in graphene-based biosensors suggest that they are poised to be valuable platforms for accelerating potency assay development. Among several potential advantages, they offer versatility for sensitive measurement of a broad range of potential biomarker types, cell biocompatibility for direct measurement, and small sample sufficiency, plus ease of use and point-of-care applicability

Optical graphene-based biosensor for nucleic acid detection; influence of graphene functionalization and ionic strength

A main challenge for optical graphene-based biosensors detecting nucleic acid is the selection of key parameters e.g. graphenic chemical structure, nanomaterial dispersion, ionic strength, and appropriate molecular interaction mechanisms. Herein we study interactions between a fluorescein-labelled DNA (FAM-DNA) probe and target single-stranded complementary DNA (cDNA) on three graphenic species, aiming to determine the most suitable platform for nucleic acid detection. Graphene oxide (GO), carboxyl graphene (GO-COOH) and reduced graphene oxide functionalized with PEGylated amino groups (rGO-PEG-NH2, PEG (polyethylene glycol)) were dispersed and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The influence of ionic strength on molecular interaction with DNA was examined by fluorescence resonance energy transfer (FRET) comparing fluorescence intensity and anisotropy. Results indicated an effect of graphene functionalization, dispersion and concentration-dependent quenching, with GO and GO-COOH having the highest quenching abilities for FAM-DNA. Furthermore, GO and GO-COOH quenching was accentuated by the addition of either MgCl2 or MgSO4 cations. At 10 mM MgCl2 or MgSO4, the cDNA induced a decrease in fluorescence signal that was 2.7-fold for GO, 3.4-fold for GO-COOH and 4.1-fold for rGO-PEG-NH2. Best results, allowing accurate target detection, were observed when selecting rGO-PEG-NH2, MgCl2 and fluorescence anisotropy as an advantageous combination suitable for nucleic acid detection and further rational design biosensor development