Mohiuddin Quadir

AFM force spectroscopy distinguishes ligand accessibility from rupture mechanics on extracellular vesicles. EpCAM–antibody interactions tend to show higher apparent off-rates than ITG–cRGD and GPC1–antibody interactions.

Zea mays (corn) seeds were coated via aqueous layered assembly of polyelectrolytes.

Size-dependent polystyrene nano- and microplastics interactions with human serum albumin reveal critical insights into protein structural changes and systemic toxicity, advancing nanoscale understanding of plastic pollution's health implications.

Cyclic polymers (CPs) make up a unique class of macromolecules characterized by their ring architecture without chain ends. Mimicking naturally occurring cyclic motifs, such as circular DNAs or viral plasmids, synthetic CPs, especially amphiphilic ones, can form supramolecular nanostructures capable of encapsulating small molecules, drugs, and nucleic acids. However, the interactions of CPs with proteins/enzymes have yet to be observed. Here, we demonstrate for the first time that poly(hydroxy butyrate)-based CPs can form nanoscale self-assemblies with a model enzyme, lysozyme, acting as enzyme/protein-stabilizing platforms. These assemblies are promoted when CPs interact with the enzyme under nonsolvent-induced phase separation conditions, displaying distinct hydrodynamic diameters (D_H), shapes, and surface charges that vary with the number-average molecular weight (M_n) of the polymer. The stability of lysozyme-CP nanoparticles depends strongly on the M_n of the CPs, with larger CPs forming nanoparticles at lower critical association concentrations. Encapsulation of lysozyme within the CPs does not alter the conformation or properties of the enzyme, as observed by circular dichroism spectroscopy. We also identify that CP nanoparticles can sustain the release/diffusion of the active protein, as evaluated by spectroscopy and the enzyme-linked immunosorbent assay. Lysozyme encapsulation in the CP was probed using site-directed spin labeling with electron paramagnetic resonance to pinpoint the presence of the enzyme spatially immobilized within the CP scaffold. Across all studied cell lines, nanoparticles composed of CPs exhibited minimal concentration-dependent cytotoxicity, regardless of the enzyme presence. While higher doses slightly reduced cell viability, it remained high at lower concentrations, indicating good biocompatibility. Meanwhile, CP nanoparticles encapsulating fluorescently labeled lysozymes promoted intracellular transport and cellular internalization of the enzyme. Collectively, this study is the first of its kind to report enzyme encapsulation within a CP scaffold, underscoring its potential in developing controlled-release enzyme/protein stabilization and transport platforms.

Single-molecule analysis reveals how ligand modifications synergistically control HDAC8 catalysis by stabilizing active conformations, providing mechanistic insights into ligand-regulated enzymatic catalysis.

Enzymes are advanced biocatalysts, while immobilizing enzymes on solid supports, particularly metal-organic frameworks (MOFs), enhances enzyme stability, reusability, and substrate selectivity. One-pot cocrystallization (CC) of enzymes in MOFs in the aqueous phase avoids enzyme size limitation and leaching; our recent CC MOF "library" offers a collection of metal-ligand combinations for customizable enzyme immobilization [ACS Appl. Mater. Interfaces 2022, 14, 46, 51619-51629]. However, CC generally suffers from low yield and stability. Mechanochemical or liquid-assisted grinding (LAG) synthesis overcomes this issue, yet most current approaches use metals, ligands, and enzymes in powder states with organic solvents, limiting eco-friendliness and enzyme compatibility. Water as an eco-friendly LAG synthesis agent (eco-LAGent) offers a greener medium to preserve protein folding states, hydration shells, and conformational flexibility, essential for activity. However, only one MOF has been reported to be synthesized this way. Due to the different metal-ligand contact mechanisms, MOFs by CC or eco-LAGent synthesis may not have the same crystal structures either, yet there is a lack of data to compare. Here, we expand the "library" of enzyme@MOF biocatalysts synthesized in an eco-LAGent, water, using abundant, low-toxicity metal ions and ligands, achieving improved thermal and pH stability and significantly enhanced enzyme@MOF yields while proving the high chance of scaling up and eventually industrial applications. Grinding also impacted the interface of metal-ligand contact─compared to aqueous-phase CC, eco-LAGent synthesis increased the crystallinity in 3 MOFs, generated new MOF structures in another 3, and improved the thermal and pH stability across most resultant enzyme@MOF cocrystals. This study generalizes the eco-LAGent synthesis to more MOFs and opens a new avenue to encapsulate enzymes in high-quality crystals with a customized selection of metal ions and ligands (according to enzymes and applications) under green and scalable conditions.

A synthetic biomolecular condensate (sBC) consisting of a prolamin-rich, plant protein, zein, has been engineered. These artificial condensates were prepared from the liquid–liquid phase (LLP) separation of a protein-rich liquid phase in water. To ensure the colloidal stability of the separated condensate, the protein was chemically modified either via quaternization with glycidyl trimethyl ammonium chloride (GTMAC) or covalently connecting poly(ethylene glycol) by reductive amination, respectively. The modified protein condensates, termed QZs and PZs (for quaternized and PEG-conjugated zein, respectively) exhibited hydrodynamic diameters (D_H) ranging from 100–300 nm and surface charge or ζ-potential of +35 to −19 mV, which ensured condensate stability via inter-particle repulsion. The size, charge, stability, and morphology of the condensate particles can be optimized by mixing both types of modified proteins (QZs and PZs) at a pre-determined stoichiometry. Such stoichiometric interactions of proteins electrostatically and thermodynamically stabilized the sBCs. These sBCs can be enriched with small molecules, which can be exchanged with their bulk environment, showcasing their potential to compartmentalize chemical species. In vitro studies indicated cellular internalization and accumulation of sBCs depending on their surface properties. Inspired by the condensation of proteins occurring in cells via LLP, this work provides a robust, scalable strategy to design stable, functional condensates that can be used as a platform to understand the structure and function of natural condensates.

Arabinoxylans (AX) are functional biopolymers, the main non-starch polysaccharides in cereals and other plants. AX is composed of xylose and arabinose, and the ester-linkage of ferulic acid to arabinose confers its bioactive properties. The backbone of AX resembles that of glycosaminoglycans, a major component of the human extracellular matrix. This study explores the potential of wheat bran AX-based scaffolds as a novel platform for the growth and development of triple-negative breast cancer (TNBC) cells, an aggressive form of breast cancer. Importantly, patients face the worst prognosis due to the stemness of the TNBC cells and the formation of hypoxic cell clumps. Wheat bran constitutes 15%- 25% of the byproducts after milling and adds limited economic value. We have extracted AX from wheat bran (WBAX) and developed soft scaffolds with Na-alginate. The scaffolds were seeded with the triple-negative breast cancer cell line MDA-MB-231. Over 21 days, cell growth and development, cell migration within the hydrogels, maintenance of cell stemness, and the formation of hypoxic regions within cell clumps were observed. These findings suggest that WBAX-based scaffolds provide a conducive environment for TNBC cell proliferation and development, offering a promising avenue for further research into cancer cell biology and potential therapeutic applications.

E pigenetic enzyme- r esponsive nano p articles (ERPs), which destabilize under the influence of histone deacetylase 8 (HDAC8), have been characterized in terms of their physicochemical, nanomechanical, and in vitro attributes. These nanoparticles were synthesized from amphiphilic block copolymers composed of poly(acetyl l-lysine) as the hydrophobic and poly(ethylene glycol) as the hydrophilic block. Upon optimizing the particle assembly process, we demonstrated that the nanoscale properties of ERPs, including hydrodynamic diameter (D_H), size distribution, and stiffness, are selectively influenced by the HDAC8 enzyme. Using ¹H NMR and circular dichroism spectroscopy, we identified that deacetylation of the lysine residues located within the hydrophobic block acts as a molecular driver for the enzyme-induced destabilization of ERPs. Comprehensive in vitro studies demonstrated that ERPs are biocompatible and noncytotoxic and can accumulate in perinuclear and several cellular organelles, including lysosomes and mitochondria. Collectively, this study attempts to establish the mechanistic background of ERP functions, providing the baseline for designing epigenetic-enzyme-sensitive nanoscale platforms.