Accurate determination of biomolecular condensate volume reveals that destabilization of condensates can lead to either swelling or shrinking of condensates, giving fundamental insights into the regulation of the volume of cellular condensates. Determination of the volume of biomolecular condensates and coacervate protocells is essential to investigate their precise composition and impact on (bio)chemical reactions that are localized inside the condensates. It is not a straightforward task, as condensates have tiny volumes, are highly viscous, and are prone to wetting. Here, we examine different strategies to determine condensate volume and introduce two new methods, with which condensate volumes of 1 μL or less (volume fraction 0.4%) can be determined with a standard deviation of 0.03 μL. Using these methods, we show that the swelling or shrinking of condensates depends on the degree of physical cross-linking. These observations are supported by Flory-Huggins theory and can have profound effects on condensates in cell biology.

Over the past decade, silk sericin has emerged as a promising material for biomedical applications, especially in tissue engineering, where fine-tuning the physicochemical properties is crucial. However, previous studies, including those on the methacrylation of sericin (yielding SS-MA), showed limited tunability. Here, we developed a photo-cross-linkable sericin-based material modified with 2-aminoethyl methacrylate (AEMA) using two synthesis routes: sequential modification of SS-MA with AEMA (SS-MA-AEMA) and an efficient one-pot synthesis (SS-AEMA). The one-pot synthesis yielded materials containing only methacrylate groups, unlike the sequential modification that yielded a combination of methacrylamides and methacrylates. Our approach resulted in superior physicochemical properties. The resulting materials, including the previously described SS-MA, exhibited a broad range of properties, such as cross-linking kinetics (0.9-64.0 s), swelling behavior (311-3775%), and mechanical properties (10-140 kPa). These properties support applications across various tissues, from dermis to fibrous tissue. The materials also demonstrated fibroblast cytocompatibility with cell viabilities exceeding 96%.

Recently, we published a study demonstrating the promising structure-activity relationship of 4-arm star polymers toward bacterial cells and biofilms. The aim of this study was to increase the number of arms to determine if this could further enhance activity via the arm-first approach, which enables access to star structures with a higher number of arms. A library of amphiphilic diblock and miktoarm star polymers was successfully synthesized, and their biological properties were assessed. The increased number of arms failed to increase activity for the diblock stars, possibly due to shielding of the cationic units located at the core from binding to the membrane, which was slightly improved for the miktoarm structures. However, the efficient synthesis of these structures shown herein could be used to synthesize star polymers with a higher cationic ratio or longer arms, thereby circumventing the limitation of reduced interaction of cationic units with the membrane.

With the advantages of less invasiveness and better shape adaptability, in situ-forming hydrogels are desired biomaterials as scaffolds, drug carriers, and so on. Herein, a negatively charged NaCl-responsive ultrashort peptide sequence (EEH) is reported whose electrostatic repulsion can be reduced through the charge-shielding effect. Under physiological conditions, its AIEgen-capped amphiphile TPE-GEEH of low concentration (1 mg/mL) presents NaCl-triggered morphological transformation from micelle to closely packed fiber with enhanced emission, which can be applied to biosense sodium ion (Na) with high sensitivity and quick response. At a slightly acidic pH, 10 mg/mL TPE-GEEH undergoes sol-gel transition upon addition of NaCl (100 mM) with improved mechanical properties, which should be useful to develop an in situ-forming hydrogel. Overall, our report provides a simple strategy to construct NaCl-responsive assemblies for potential application in biosensors and drug delivery system.

Bone defects resulting from congenital anomalies and trauma pose significant clinical challenges for orthopedics surgeries, where bone tissue engineering (BTE) aims to address these challenges by repairing defects that fail to heal spontaneously. Despite numerous advances, BTE still faces several challenges, i.e., difficulties in detecting and tracking implanted cells, high costs, and regulatory approval hurdles. Biomaterials promise to revolutionize bone grafting procedures, heralding a new era of regenerative medicine and advancing patient outcomes worldwide. Specifically, novel bioactive biomaterials have been developed that promote cell adhesion, proliferation, and differentiation and have osteoconductive and osteoinductive characteristics, stimulating tissue regeneration and repair, particularly in complex skeletal defects caused by trauma, degeneration, and neoplasia. A wide array of biological therapeutics for bone regeneration have emerged, drawing from the diverse spectrum of gene therapy, immune cell interactions, and RNA molecules. This review will provide insights into the current state and potential of future strategies for bone regeneration.

Sensory capabilities are crucial for cells to interact with their environment. To mimic these functions in synthetic cells, we developed sensory globular protein vesicles (GPVs) made entirely of recombinant fusion proteins through self-assembly under aqueous conditions. GPVs demonstrate sensory functions via the formation of the FKBP-FRB ternary complex with the signaling molecule, rapamycin. The sensory domain of FKBP or FRB was genetically fused to a fluorescent protein and leucine zipper, which self-assemble into vesicles by forming amphiphilic building blocks through high-affinity binding to a counter leucine zipper fused to an elastin-like polypeptide (ELP) above its lower critical solution temperature. We observed intervesicle aggregation in a time- and concentration-dependent manner upon rapamycin binding, confirmed by colocalization studies and statistical analysis. This system enhances our understanding of protein vesicle functionality for sensing and offers a basis for exploring GPVs as models to replicate key cellular processes in synthetic cells.

Solid tumors reprogram metabolic pathways to meet their biosynthesis demands, resulting in elevated levels of metabolites in the tumor microenvironment (TME), including lactate. Excessive accumulation and active transportation of lactate within the TME drives tumor progression, metastasis, and immunosuppression. Interruption of TME lactate metabolism is expected to restore antitumor responses and sensitize tumor immunotherapy. Herein, we developed phenylboronic acid- and pyridine-modified poly(amidoamine) dendrimer/copper(II) (Cu(II)) complexes, namely, D-Cu complexes, to deliver monocarboxylate transporter 4 siRNA (siMCT4) and disrupt the tumor lactate shuttle. The D-Cu complexes are shown to have a Cu(II)-mediated chemodynamic effect and -weighted magnetic resonance imaging potential ( relaxivity = 1.19 mM s), enabling effective siMCT4 delivery to inhibit lactate efflux within cancer cells. In combination with a CD11b immune agonist, the treatment of D-Cu/siMCT4 polyplexes in a mouse breast tumor model alleviates local TME immunosuppression, leading to excellent inhibition of both primary tumor growth and lung metastasis.

Injectable hydrogels offer a minimally invasive approach to treating intervertebral disc degeneration, a prevalent condition that affects 90% of individuals and often leads to significant pain and disability. Despite being a critical yet often overlooked issue that could lead to suboptimal therapeutic outcomes, the mechanical integrity of these gels frequently diminishes postinjection due to the injection process itself. To address this challenge, our research developed a silk-nanofibril-based hydrogel enhanced through simple polymerization of dopamine. The resulting hydrogel not only effectively preserved its modulus at over 1000 Pa postinjection, matching the mechanical properties of the nucleus pulposus, but also significantly enhanced its antioxidative properties to four times that of the original silk nanofibril-based hydrogel. Furthermore, both cell-based and animal studies substantiated that such a silk nanofibril-based hydrogel integrated with polydopamine exhibited significant therapeutic efficacy in the injectable treatment of intervertebral disc degeneration. Therefore, this work introduced a new perspective on the design of injectable hydrogels that could effectively address both the mechanical and biochemical challenges of degenerative disc diseases, providing a platform for subsequent therapeutic interventions.

Cellulose esters are used in Food and Drug Administration-approved oral formulations, including in amorphous solid dispersions (ASDs). Some bear substituents with terminal carboxyl moieties (e.g., hydroxypropyl methyl cellulose acetate succinate (HPMCAS)); these ω-carboxy ester substituents enhance interactions with drug molecules in solid and solution phases and enable pH-responsive drug release. However, the synthesis of carboxyl-pendent cellulose esters is challenging, partly due to competing reactions between introduced carboxyl groups and residual hydroxyls on different chains, forming either physically or covalently cross-linked systems. As we explored ring-opening reactions of cyclic anhydrides with cellulose and its esters to prepare polymers designed for high ASD performance, we became concerned upon encountering gelation. Herein, we probe the complexity of such ring-opening reactions in detail, for the first time, utilizing rheometry and solid-state C NMR spectroscopy. Gelation in these ring-opening reactions was caused predominantly by physical interactions, progressing in some cases to covalent cross-links over time.

Enzymes are crucial for various technological applications, but their inherent instability and short lifespan pose challenges. This study presents facile immobilized enzyme technology with the development of thermoresponsive enzyme-polymer conjugates (EPCs), using glucose oxidase (GOx) as a model enzyme, to address these limitations. By conjugating heteropolymers to the glycan moieties of GOx through a precise polymerization process, we could modulate the lower critical solution temperature of the EPCs, enhancing enzyme performance without compromising its active site. The EPCs demonstrate a switchable behavior that facilitates efficient homogeneous catalysis and easy heterogeneous separation, reducing costs and environmental impact in industrial applications. Our strategy presents a versatile platform for creating efficient biocatalysts with tunable properties, marking a step forward in sustainable and cost-effective bioprocessing.

Flexible electronic devices such as wearable sensors are essential to advance human-machine interactions. Conductive eutectogels are promising for wearable sensors, despite their challenges in self-healing and adhesion properties. This study introduces a multifunctional eutectogel based on a novel polymerizable deep eutectic solvent (PDES) prepared by the incorporation of diallyldimethylammonium chloride (DADMAC) and glycerol in the presence of polycyclodextrin (PCD)/dopamine-grafted gelatin (Gel-DOP)/oxidized sodium alginate (OSA). The synthesized eutectogel has reversible Schiff-base bonds, hydrogen bonds, and host-guest interactions, which enable rapid self-healing upon network disruption. GPDO-15 eutectogel has significant tissue adhesion, high stretchability (419%), good ionic conductivity (0.79 mS·cm), and favorable antibacterial and self-healing properties. These eutectogels achieve 90% antibacterial effect, show excellent biocompatibility, and can be used as sensors to monitor human activities with strong stability and durability. The studies indicate that the eutectogels can improve the wound healing process which makes them an effective option for biological dressings.

Ionic complexes of electrostatically charged biomacromolecules are key players in various biological processes like nucleotide transportation, organelle formation, and protein folding. These complexes, abundant in biological systems, contribute to the function, responsiveness, and mechanical properties of organisms. Coherent with these natural phenomena, hydrogels formed through the complexation of oppositely charged polymers exhibit unique attributes, such as rapid self-assembly, hierarchical microstructures, tunable properties, and protective encapsulation. Consequently, polyelectrolyte complex (PEC) hydrogels have garnered considerable interest, emerging as an up-and-coming platform for various biomedical applications. This review outlines the underlying principles governing PEC hydrogels. The classification of polyelectrolytes and the self-assembly of PEC hydrogels are discussed, including the factors influencing their self-assembly process. Recent developments of PEC hydrogels for biomedical applications, including drug delivery, tissue engineering, wound healing and management, and wearable sensors, are summarized. This review concludes with the prospective directions for the next generation of PEC hydrogel research.

We synthesized a series of amphiphilic cationic poly(ethylene glycol)--poly(β-amino acid) derivatives with various lengths of PEG to investigate the effects of PEG lengths on mRNA transfection. The surface charges of the polyplexes with a DP ≥ 4 gradually decreased as DP increased. This indicated that hydrophilic PEG with a DP ≥ 4 was exposed on the surface of the polyplexes, which was further confirmed using H NMR. Polyplexes with a DP ≤ 4 exhibited mRNA transfection efficacy similar to that of homopolymers. However, the transfection efficacy of the polyplex with a DP ≥ 12 markedly decreased, mainly because of the decreased cellular uptake and stability of the polyplexes against serum albumin. This indicated that the PEG length considerably affected the delivery efficacy of IVT mRNA. Our results provide useful information for the fundamental polymer design to optimize the PEG length of amphiphilic cationic polymers for systemic IVT mRNA delivery.

Diabetic wounds are increasingly common and challenging to treat due to high infection risks in a high-glucose environment. Effective treatment requires wound dressings that combat infections, while promoting angiogenesis and skin regeneration. This study presents a hydrogel-based drug delivery system made from cellulose designed to accelerate diabetic wound healing by eliminating bacterial infections. The hydrogel, formed by linking phenylboronic acid-grafted oxidized methylcellulose (POMC) with poly(vinyl alcohol) (PVA), exhibits self-healing and injectable properties. It is further enhanced by adding type I recombinant human collagen (rhCOL1) to stimulate cell growth and angiogenesis and mesoporous zinc oxide (mZnO) for antibacterial and anti-inflammatory effects. Upon application, the hydrogel degrades under pH/ROS stimuli, releasing mZnO and rhCOL1 in a controlled manner that matches the wound healing stages. In vivo tests show that the hydrogel effectively eliminates bacteria, reduces inflammation, and promotes rapid skin regeneration, making it a promising solution for treating diabetic wounds.

Amphiphilic gradient copolymers are promising alternatives to block copolymers for self-assembled nanomaterials due to their straightforward synthesis via statistical copolymerization of monomers with different reactivities and hydrophilicity. By carefully selecting monomers, nanoparticles can be synthesized in a single step through gradient copolymerization-induced self-assembly (gPISA). We synthesized highly sensitive F MRI nanotracers via aqueous dispersion gPISA of hydrophilic poly(ethylene glycol) methyl ether methacrylate (PEGMA) with core-forming ,-(2,2,2-trifluoroethyl)acrylamide (TFEAM). The PPEGMA-grad-PTFEAM nanoparticles were optimized to achieve spherical morphology and exceptional F MRI performance. Noncytotoxicity was confirmed in Panc-1 cells. In vitro F MR relaxometry and imaging demonstrated their diagnostic imaging potential. Notably, these gradient copolymer nanotracers outperformed block copolymer analogs in F MRI performance due to their gradient architecture, enhancing F relaxivity. The synthetic versatility and superior F MRI performance of gradient copolymers highlight their potential in advanced diagnostic imaging applications.

The invasion of bacteria and inflammation impeded infected wounds heal. Here, a hyaluronan-based scaffold (HAG--C) was designed by cross-linking with gallic acid-modified gelatin to provide a protein microenvironment and decorated with cathelicidin-BF (CBF), a natural antimicrobial peptide, to remove bacterial infections and reverse the inflammatory environment. , HAG--C presented an antibacterial effect on and . Meanwhile, it could drive the phenotypic switch of macrophage from M1 to M2 to accelerate tissue remodeling. In a mouse model of -infected total skin defects, HAG--C inhibited the process of infection at the beginning of the wound and then regulated the M1 macrophage transformed to M2 phenotype on day 12. In addition, HAG--C induced collagen deposition, and reduced the expression of TNF-α, thereby significantly accelerating the reconstruction of infected wounds.

Cellulose nanocrystals (CNC) have been significantly developed as a building block material for the design of novel functional materials in many fields such as biomedicine, nanotechnology, and materials science due to their excellent optical properties, biocompatibility, and sustainability. Improving the redispersibility of CNC in the sustainable processing of nanocellulose has been a challenge because intense hydrogen bond interaction leads to irreversible aggregation, making CNC difficult to redisperse and increasing the cost of storage and transportation of CNC. Hydroxypropyl cellulose (HPC) is an important hydroxy propylated cellulose ether. As a water-soluble cellulose derivative, HPC has a polyhydroxy structure similar to that of CNC, which leads to good compatibility and high affinity between HPC and CNC. In this work, HPC of different molecular weights was comixed with CNC of different contents, which was then dried using different methods, and the dried samples were redispersed in water. The addition of HPC improved the redispersibility of the CNC. Finally, the redispersed suspension was also redried to form a film, which was found to retain its structure color. These results provide an important avenue for the redispersion of dried CNC and for the development of functional materials from redispersed CNC.

Thermoplastic properties in cellulosic materials can be achieved by opening the glucose rings in cellulose and introducing new functional groups. Using molecular dynamics, we simulated amorphous cellulose and eight modified versions under dry and moist conditions. Modifications included ring openings and functionalization with hydroxy, aldehyde, hydroxylamine, and carboxyl groups. These modifications were analyzed for density, glass transition temperature, thermal expansivity, hydrogen bond features, changes in energy term contributions during deformation, diffusivity, free volume, and tensile properties. All ring-opened systems exhibited higher molecular mobility, which, consequently, improved thermoplasticity (processability) compared to that of the unmodified amorphous cellulose. Dialcohol cellulose and hydroxylamine-functionalized cellulose were identified as particularly interesting due to their combination of high molecular mobility at processing temperatures (425 K) and high stiffness and strength at room temperature (300 K). Water and smaller side groups improved processability, indicating that both steric effects and electrostatics have a key role in determining the processability of polymers.

The urgent need for new antimicrobial compounds has led scientists to explore antimicrobial peptides (AMPs) and antimicrobial polymers as solutions for multidrug resistance. In this study, we synthesized copolymers with cationic and hydrophobic moieties by free-radical polymerization (FRP) using a chain transfer agent to control molecular weights. The potential of natural products as part of the hydrophobic moiety was evaluated, along with variations in their monomer content (13-25%) and the molecular weight (MW) of the copolymer (5000-20,000 g·mol). Hydrophobicity was evaluated using the theoretical Log values and surface areas (SAs). Biological assays included antimicrobial activity against and standard strains, hemolytic activity in red blood cells (RBC), and cytotoxicity tests against HEK293T cells. Keys findings indicate that copolymers with tropolone moieties, lower MWs, and an optimal balance between hydrophobic and cationic moieties show a promising basis for future generations of antimicrobials.

The biocompatibility and renewability of starch-based hydrogels have made them popular for applications across various sectors. Their tendency to incur damage after repeated use limits their effectiveness in practical applications. Improving the mechanical properties and self-healing of hydrogels simultaneously remains a challenge. This study introduces a new self-healing hydrogel, synthesized by grafting acrylamide onto starch using ceric ammonium nitrate (CAN) as an initiator, followed by borax cross-linking. We systematically examined how the starch-to-monomer ratio, borax concentration, and CAN concentration impact the grafting reactions and overall performance of the hydrogels. The addition of borax significantly reinforced the strength of the hydrogel; the maximum storage modulus increased by 1.8 times. Thanks to dynamic borate ester and hydrogen bonding, the hydrogel demonstrated remarkable recovery properties and responsiveness to temperature. We expect that the present research could broaden the application of starch-based hydrogels in agriculture, sensors, and wastewater treatment.