Pesce, C. | bioRxiv Science

bioRxiv2025

On the biodegradation of micropatterned polymeric film

AO_SCPLOWBSTRACTC_SCPLOWPolymeric implants for local drug delivery offer significant advantages for treating various medical conditions by enabling the temporal and spatial control of drug release, improving efficacy, and reducing systemic side effects. In this context, {micro}MESH, a 20 m thin, dual-compartmentalized film comprising a poly(lactic-co-glycolic acid) (PLGA) micronetwork intercalated with a polyvinyl alcohol (PVA) microlayer, represents an interesting opportunity as its geometry can be systematically and accurately micropatterned during the fabrication process, enabling the systematic analysis of the effect of geometry on biodegradation rates mechanisms. In this study, four different {micro}MESH films were realized with different surface area-to-volume ratios (Sa/V), ranging from 0.67 to 1.7 {micro}m-1. After characterizing the {micro}MESH geometry via fluorescent and scanning electron microscopy, biodegradations studies were performed up to 60 days in different media to assess the mass loss of PLGA, the reduction in PLGA molecular weight, and the formation of macroscopic defects - pores, holes and crack - within the PLGA micronetwork. By comparing the four {micro}MESH films among themselves and to a flat, continuous PLGA slab (FLAT), it was confirmed the importance of the surface-to-volume ratio and demonstrated that {micro}MESH with higher Sa/V ratios exhibited slower degradation rates compared to FLAT. Scanning electron microscopy images of the PLGA micronetworks revealed morphological changes indicative of bulk erosion, including surface roughening and pore formation, in FLAT and {micro}MESH configurations with low Sa/V ratios. These findings confirm that film micropatterning significantly influences degradation kinetics.

bioengineering↗

bioRxiv2020

Repeated gain and loss of a single gene modulates the evolution of vascular pathogen lifestyles

Vascular pathogens travel long distances through host veins leading to life-threatening, systemic infections. In contrast, non-vascular pathogens remain restricted to infection sites, triggering localized symptom development. The contrasting features of vascular and non-vascular diseases suggest distinct etiologies, but the basis for each remains unclear. Here, we show that the hydrolase CbsA acts as a phenotypic switch between vascular and non-vascular plant pathogenesis. cbsA was enriched in genomes of vascular phytopathogenic bacteria in the Xanthomonadaceae family and absent in most non-vascular species. CbsA expression allowed non-vascular Xanthomonas to cause vascular blight while cbsA mutagenesis resulted in reduction of vascular or enhanced non-vascular symptom development. Phylogenetic hypothesis testing further revealed that cbsA was lost in multiple non-vascular lineages and more recently gained by some vascular subgroups, suggesting that vascular pathogenesis is ancestral. Our results overall demonstrate how the gain and loss of single loci can facilitate the evolution of complex ecological traits.

microbiology↗