Biology subjects

Murthy, B.

Publications and source records attributed to Murthy, B..

3 recordsLinked to original sources

bioRxiv2025

Layer-by-Layer Nanoparticle Outer Polyion Impacts Protein Corona Formation

Nanoparticles (NPs) can be engineered to achieve targeted delivery with strategies based on surface modifications. These include layer-by-layer (LbL) NPs, modular electrostatically assembled carriers with tunable surface properties altered by changes to the outer polyion layer. Variations in these polymers dictate intracellular trafficking and biodistribution patterns. As NPs are administered, a layer of protein adsorbs to their surfaces, forming a protein corona that affects NP properties, alters biodistribution, and ultimately, impacts therapeutic efficacy. We hypothesized that some differences in LbL NP performance are due, in part, to variations in the resulting protein coronas. To study them, we first optimized an ultrafiltration method to effectively isolate LbL NPs with their protein corona. Following incubation in conditioned media, anionic homopolypeptide outer layers, such as poly-L-aspartic acid (PLD) and poly-L-glutamic acid (PLE), and LbL NPs with the bioinert polymer poly(acrylic acid) (PAA) had the lowest amount of protein associated, lower than conventional PEG liposomes. While mass spectroscopy revealed changes in the protein composition among LbL NPs; albumin, alpha-2-macroglobulin, and apolipoprotein B were most abundant. In vitro, pre-formed protein coronas reduced uptake in macrophages but increased uptake in ovarian cancer cells for certain LbL NP outer layers. In vivo, LbL NP outer layer influenced both serum half-life and biodistribution. Overall, this work highlights that LbL NPs can be designed to control protein corona formation, and supports that further understanding NP interactions with biological fluids is essential for designing clinically translatable NP platforms. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/670086v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@18a2a66org.highwire.dtl.DTLVardef@1e5b755org.highwire.dtl.DTLVardef@676af2org.highwire.dtl.DTLVardef@19e3b34_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Investigating Bio-Nano Interactions of PEGylated Cationic Polyamidoamine (PAMAM) Dendrimers within Synovial Joints

Delivering therapeutics directly to synovial joints to treat osteoarthritis (OA) is challenging due to the dense negatively charged cartilage matrix and rapid turnover of synovial fluid, leading to high clearance rates. Our lab has identified polyamidoamine (PAMAM) dendrimers as optimal nanocarriers to overcome delivery challenges to cartilage due to their positive charge and small size, which enables them to bind to cartilage and diffuse through tissue to deliver therapeutics to chondrocytes. Previously, we have developed and characterized dendrimers functionalized with polyethylene glycol (PEG), demonstrating improved biocompatibility and enhanced transport through cartilage matrix. To improve the design of our therapeutic system, in this next phase of work, we characterized dendrimer-protein interactions or protein coronas that form on dendrimers after being immersed in synovial fluid. We also analyzed how synovial fluid protein coronas affect biological outcomes of dendrimers in synovial joints, specifically uptake in cartilage and internalization by chondrocytes. We identified that protein coronas can reduce dendrimer uptake in cartilage and chondrocytes; however, uptake reduction is mitigated by varying PEG chain length and density. Although protein coronas can be perceived as "biological barriers" to uptake, we demonstrate that dendrimers conjugated with insulin-like growth factor 1 (IGF-1) have better engagement with IGF-1 receptors after being pre-coated with a synovial fluid protein corona. Overall, these studies offer further insight into the mechanisms of how positively charged dendrimers target and transport through cartilage, bridging knowledge gaps between ex vivo and in vivo work. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=127 SRC="FIGDIR/small/668990v2_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@9298ccorg.highwire.dtl.DTLVardef@6d85aeorg.highwire.dtl.DTLVardef@63838dorg.highwire.dtl.DTLVardef@151ca4a_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2025

Learning reorganizes dendritic and stabilizes axonal initial segment inhibitory synapses in CA1 pyramidal neurons

Structural synaptic plasticity underlies the changes in brain connectivity required for learning and memory. Inhibitory synapses (INS) target all subcellular domains of excitatory pyramidal neurons (PNs), including dendrites, somata and axon initial segments (AIS). These subcellular domains have distinct molecular, structural and physiological profiles which underlie their functions. How structural plasticity of INS supports these functions as well as emerging properties such as memory is largely unknown. To tackle these questions we tracked INS on dendrites, somata and AIS of PNs in the dorsal hippocampal CA1 area of mice over two weeks. Size and temporal dynamics of INS showed a strong compartmentalization and dendritic INS were less dynamic than dendritic spines. Trace fear conditioning led to reorganization of dendritic INS and to stabilization of AIS INS but had a minimal effect on dendritic spines. Finally, mathematical modelling allowed us to probe the mechanisms underlying stabilization of INS upon learning.

neuroscience↗