Caffrey, E. | bioRxiv Science

bioRxiv2025

PolyGraph - Flexible, Biocompatible & Electrically Optimised Graphene-Polymer Composites for Next-Generation Neural Interfaces

Neural interfacing materials must deliver exceptional electrochemical performance, while integrating safely with the central nervous system. In this study we develop PolyGraph, a flexible, conductive, and biocompatible graphene-polycaprolactone (PCL) nanocomposite designed to strike this balance, which enables fabrication of conformable multichannel microelectrode arrays. Optimised liquid-phase exfoliation produces conductive, biocompatible PVP-stabilised graphene nanosheets, which are incorporated into PCL to form flexible, processable composites - PolyGraph. This material demonstrates bio- and immuno-compatibility with sensitive primary and iPSC-derived neuronal and glial cells. PolyGraph achieves low impedance ([~]1.6 {Omega} cm2 @ 1 kHz) and high charge injection capacity (11.7 mC/cm2 for a 100 ms pulse), enhanced by NaOH surface roughening and AuPd coating. Leveraging their processability, PolyGraph composites are fabricated into flexible, individually isolated microneedle electrode arrays with biomimetic soft hyaluronic acid backings. These arrays demonstrate bidirectional neural interfacing capabilities, enabling both the delivery of controlled stimulation pulses in physiological buffer and high-resolution neuronal recording in murine brain slices, with machine learning-based event classification. Together, these advances establish PolyGraph as an optimal material platform for next-generation brain-computer interfaces and soft bioelectronic devices. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=109 SRC="FIGDIR/small/673516v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@9beea5org.highwire.dtl.DTLVardef@150be08org.highwire.dtl.DTLVardef@1ec24d2org.highwire.dtl.DTLVardef@658209_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical Abstract & TOC Text PolyGraph, a flexible graphene-polycaprolactone nanocomposite, unites conductivity, biocompatibility, and processability for next-generation neural interfaces. Fabricated into microneedle arrays with ultra-flexible backings, PolyGraph enables bidirectional neuronal recording and stimulation in brain tissue, advancing brain-computer interface (BCI) and soft bioelectronic applications.

bioengineering↗

bioRxiv2022

Fermented foods restructure gut microbiota and promote immune regulation via microbial metabolites

Fermented foods are ancient and ubiquitous, thought to be consumed in nearly every culture over the last 10,000 years and as part of the hominin diet for millions of years. A growing body of evidence supports their potential health benefits, but the mechanistic basis of their effects on the gut microbiome and host immunity remain to be elucidated. Fermented foods are diverse, each representing a complex mixture of food, microbes, and metabolites creating a significant challenge to disentangle the effects of individual components. Herein, we further define the chemical signature of individual fermented foods to categorize them based on the primary metabolic end-products of fermentation. Using mouse models, we find that fermented foods have both microbiome directed as well as differential host directed effects that correspond to their metabolite composition. Fermented food brine drink shows site-specific restructuring of the gut microbiome and promotion of tolerogenic barrier immunity; fractionation of the brine to examine the effects of the microbe-free, metabolite rich supernatant shows similar activity. Lactate, the main metabolite of lactic acid fermentation and the major metabolite within the brine drink, when administered in water, fuels a trans-kingdom metabolic network to selectively promote the growth of Akkermansia muciniphila. in the small intestine, while promoting immune tolerance via an increase in microbiota-dependent Regulatory T-cells. These findings suggest that the beneficial effects of fermented food consumption can be mediated by microbial metabolites within fermented foods, independent of microbial content, and highlight the importance of further defining the diverse chemical landscape of fermented foods to inform their potential health benefits and therapeutic use.

microbiology↗