Biology subjects

Dias, R. A.

Publications and source records attributed to Dias, R. A..

3 recordsLinked to original sources

bioRxiv2026

Cotton fabrics functionalized with hydroxyl-rich graphene derivatives and silver nanowires: washing resistance and preliminary antibacterial activity against Escherichia coli

Cotton-based antimicrobial textiles are attractive for applications requiring improved microbiological control, but their performance depends on effective surface functionalization and retention of the active materials after use and washing. In this work, cotton fabrics were functionalized with hydroxyl-rich graphene oxide (HGO), hydroxyl-rich reduced graphene oxide (H-rGO), and silver nanowires (AgNWs), either individually or in combined treatments, to investigate their deposition onto the textile surface, washing resistance, and preliminary antibacterial activity. The treated fabrics were prepared by immersion-based coating procedures, and the persistence of the deposited materials after repeated washing was evaluated by UV-Vis analysis of the residual wash solutions. Surface morphology before and after washing was examined by scanning electron microscopy. The results showed that graphene-based coatings, particularly HGO, exhibited stronger retention on cotton fibers, while AgNWs were partially retained after repeated washing cycles. SEM images confirmed the deposition of AgNWs on the cotton surface and showed that part of the coating remained associated with the fibers after washing. A preliminary antibacterial assay against Escherichia coli indicated that nanomaterial-treated fabrics inhibited bacterial growth relative to untreated controls, with the combined HGO/AgNWs treatment showing the most promising inhibitory trend under the tested conditions. These findings demonstrate the feasibility of producing cotton fabrics functionalized with hydroxyl-rich graphene derivatives and silver nanowires, supporting their potential as proof-of-concept antibacterial textiles with partial washing resistance.

microbiology↗

bioRxiv2025

Fueling a predator death-trap: Trophic subsidies and the risk of management-induced collapse in a predator-prey system

O_LIAnthropogenic subsidies create complex ecological dynamics, yet their interaction with invasive species management is poorly understood. Managing subsidies or predators in isolation risks perverse outcomes, including population collapses, demanding a more holistic understanding. C_LIO_LIWe employed a Pattern-Oriented Inference framework to synthesize multiple lines of evidence for the endemic Noronha skink (Trachylepis atlantica) across an archipelago. We analyzed three key patterns using complementary methods: (i) population density, estimated via capture-mark-recapture and negative binomial GLMs of count data; (ii) individual body size, using gamma GLMs; and (iii) injury rates, via tail-autotomy analysis. C_LIO_LIWe documented a dramatic density gradient driven by predation pressure. Skink populations were over three times denser on predator-light secondary islands (0.411 ind/m2, 95% CI: 0.297-0.568) than in predator-rich PARNAMAR (0.125 ind/m2, 95% CI: 0.090-0.174). Although anthropogenic subsidies boosted density by 82% in the inhabited APA (0.227 ind/m2, 95% CI: 0.174-0.297), this was insufficient to overcome the severe impact of invasive predators. C_LIO_LIThis created a paradox where density, a traditional population success metric, was inverse to size, an indicator of individual fitness. On the main island, although the subsidized APA was denser than PARNAMAR, individual condition was no better. Adult males in the APA were as small as those in the lowest-density sites and significantly smaller than males on the secondary islands. Predation pressure explains this gradient, with tail-loss injury rates peaking in the APA (29.3%), remaining high in PARNA (25.0%), and dropping about 50% on the secondary islands (15.0%). C_LIO_LISynthesis and applications: The convergence of these patterns supports a "predator death-trap" hypothesis, where trophic subsidies in the inhabited APA fuel high skink recruitment, masking extreme mortality from a subsidized predator community and other anthropogenic threats. This dynamic produces high population turnover and truncates size structure by selectively removing larger, older adults and may explain patterns seen elsewhere. Our findings have critical management implications: removing food subsidies without concurrent, effective control of key invasive predators could trigger a population collapse. We advocate integrated, multi-species management and provide robust evidence for the threatened status of this endemic reptile. C_LI

ecology↗

bioRxiv2024

Invasion of glioma cells through confined space requires membrane tension regulation and mechano-electrical coupling via Plexin-B2

Glioblastoma (GBM) is a malignant brain tumor with uncontrolled invasive growth. Here, we demonstrate how GBM cells usurp guidance receptor Plexin-B2 to gain biomechanical plasticity for polarized migration through confined space. Using live-cell imaging to track GBM cells negotiating microchannels, we reveal active endocytosis at cell front and filamentous actin assembly at rear to propel GBM cells through constrictions. These two processes are interconnected and governed by Plexin-B2 that orchestrates cortical actin and membrane tension, shown by biomechanical assays. Molecular dynamics simulations predict that balanced membrane and actin tension are required for optimal migratory velocity and consistency. Furthermore, Plexin-B2 mechanosensitive function requires a bendable extracellular ring structure and affects membrane internalization, permeability, phospholipid composition, as well as inner membrane surface charge. Together, our studies unveil a key element of membrane tension and mechanoelectrical coupling via Plexin-B2 that enables GBM cells to adapt to physical constraints and achieve polarized confined migration.

cancer biology↗