Multi-scale analysis of the phase separation behavior of FUS mutants.

Fused in sarcoma (FUS) is an intrinsically disordered RNA-binding protein that helps to regulate transcription and RNA transport while reversibly assembling into membraneless organelles (MLOs). Some mutations of FUS can promote irreversible aggregation, contributing to neurodegenerative diseases. We previously reported a multi-scale computational framework combining a series of molecular dynamics simulations (MD) followed by lattice Monte Carlo (MC) simulations to describe the tendency and dynamics of the assembly and disassembly of intrinsically disordered proteins (IDPs) using wild-type (WT)-FUS as an illustrative example.

Multiscale Computational Framework for the Liquid-Liquid Phase Separation of Intrinsically Disordered Proteins.

The reversible assembly of intrinsically disordered proteins (IDPs) to form membraneless organelles (MLOs) is a fundamental process involved in the spatiotemporal regulation in living cells. MLOs formed via liquid-liquid phase separation (LLPS) serve as molecule-enhancing hubs to regulate cell functions. Owing to the complexity and dynamic nature of the protein assembly via a network of weak inter- and intra-molecular interactions, it is challenging to describe and predict the LLPS behavior.

Self-adjuvanted L-arginine-modified dextran-based nanogels for sustained local antigenic protein delivery to antigen-presenting cells and enhanced cellular and humoral immune responses.

In the development of cancer vaccines, antigens are delivered to elicit potent and specific T-cell responses to eradicate tumour cells. Nonetheless, successful vaccines are often hampered by the poor immunogenicity of tumour antigens, rapid clearance by the innate immunity, and limited cross-presentation on MHC-I to activate CD8 T-cells arm. To address these issues, we developed dextran-based nanogels to promote antigen uptake, storage, and cross-presentation on MHC-I, while directing immunogenic maturation of the antigen-presenting cells (APCs).

Vaccine delivery by zwitterionic polysaccharide-based hydrogel microparticles showing enhanced immunogenicity and suppressed foreign body responses.

The controlled release of antigens from injectable depots has been actively pursued to achieve long-lasting immune responses in vaccine development. Nonetheless, subcutaneous depots are often susceptible to foreign body responses (FBRs) dominated by macrophage clearance and fibrotic encapsulation, resulting in limited antigen delivery to target dendritic cells (DCs) that bridge innate and adaptive immunity. Here, we aim to develop a long-term antigen depot that can bypass FBR and engage DCs to mature and migrate to lymph nodes to activate antigen-specific T-cells.

Low-intensity low-frequency ultrasound mediates riboflavin delivery during corneal crosslinking.

We employed the mechanical effect from 40 kHz ultrasound (US) to improve the delivery of riboflavin into corneal stroma for collagen crosslinking, which can benefit the treatment of keratoconus and other corneal ectasias. Experiments were conducted, first with porcine corneas ex vivo and then with New Zealand white rabbits in vivo, at varying mechanical index (MI) and sonication time. Results showed that 15 min of US applied on the cornea at MI = 0.

Construction of multiphasic membraneless organelles towards spontaneous spatial segregation and directional flow of biochemical reactions.

Many intracellular membraneless organelles (MLOs) appear to adapt a hierarchical multicompartment organization for efficient coordination of highly complex reaction networks. Recapitulating such an internal architecture in biomimetic platforms is, therefore, an important step to facilitate the functional understanding of MLOs and to enable the design of advanced microreactors. Herein, we present a modular bottom-up approach for building synthetic multiphasic condensates using a set of engineered multivalent polymer-oligopeptide hybrids.

Correction: Fusogenic peptide modification to enhance gene delivery by peptide-DNA nano-coassemblies.

Correction for 'Fusogenic peptide modification to enhance gene delivery by peptide-DNA nano-coassemblies' by Ruilu Feng , , 2022, , 5116-5120, https://doi.org/10.1039/D2BM00705C.

Recent advances in surface modification of micro- and nano-scale biomaterials with biological membranes and biomolecules.

Surface modification of biomaterial can improve its biocompatibility and add new biofunctions, such as targeting specific tissues, communication with cells, and modulation of intracellular trafficking. Here, we summarize the use of various natural materials, namely, cell membrane, exosomes, proteins, peptides, lipids, fatty acids, and polysaccharides as coating materials on micron- and nano-sized particles and droplets with the functions imparted by coating with different materials. We discuss the applicability, operational parameters, and limitation of different coating techniques, from the more conventional approaches such as extrusion and sonication to the latest innovation seen on the microfluidics platform.

Stochastic Lattice-Based Modeling of Macromolecule Release from Degradable Hydrogel.

A three-dimensional lattice-based model has been developed to describe the release of a macromolecular drug encapsulated in a degradable hydrogel. The degradation-induced network heterogeneity is considered by assigning varying diffusion coefficients to the lattice sites based on the fitted exponential node-diffusivity relationship. As time passes, due to the degradation of crosslink nodes, diffusivity values in lattice sites progress to higher values.

Fusogenic peptide modification to enhance gene delivery by peptide-DNA nano-coassemblies.

Endosomal escape is a major obstacle for non-viral nucleic acids delivery. Here, we attached by click reaction a fusogenic peptide (L17E) onto peptide self-assembled disks (∼17 nm), which mimicked the functional subunits of the virus capsid. These peptide disks then spontaneously co-assembled with DNA to form patterned nanostructures (∼100 nm) as viral mimics.

Molecular logic operations from complex coacervation with aggregation-induced emission characteristics.

Leveraging complex coacervation of a polycation and a bivalent anion with aggregation-induced emission characteristics, we accomplish eight basic logic operations with environmental stimuli as inputs, producing Boolean-like fluorescence intensity or turbidity 'outputs' with contrast higher than one order of magnitude. Storage of information of a fluorescent pattern and thermo-sensor applications are also demonstrated.

mRNA Delivery and Storage by Co-Assembling Nanostructures with Designer Oligopeptides.

Broadening the applicable tools for mRNA delivery provides more flexibility in research and those proven effective and safe can potentially be translated for clinical use. We report here a 27-amino acid peptide sequence mimicking the viral capsid protein, termed pepMAX, capable of co-assembling with mRNA into 100-150 nm nanostructures for efficient transfection of multiple cell lines. The mRNA loading and N/P ratio have been systematically optimized for each cell line.

Multifaceted Cargo Recruitment and Release from Artificial Membraneless Organelles.

Liquid-liquid phase separation (LLPS) drives membraneless organelles (MLOs) formation for organizing biomolecules. Artificial MLOs (AMLOs) have been constructed mostly via the LLPS of engineered proteins capable of regulating limited types of biomolecules. Here, leveraging a minimalist AMLO, driven by LLPS of polymer-oligopeptide hybrids, enrichment, recruitment, and release of multifaceted cargoes are quantitatively shown, including small fluorescent molecules, fluorophore-containing macromolecules, proteins, DNAs, and RNAs.

Nucleic Acids Modulate Liquidity and Dynamics of Artificial Membraneless Organelles.

Liquid-liquid phase separation (LLPS) emerges as a fundamental underlying mechanism for the biological organization, especially the formation of membraneless organelles (MLOs) hosting intrinsically disordered proteins (IDPs) as scaffolds. Nucleic acids are compositional biomacromolecules of MLOs with wide implications in normal cell functions as well as in pathophysiology caused by aberrant phase behavior. Exploiting a minimalist artificial membraneless organelles (AMLO) from LLPS of IDP-mimicking polymer-oligopeptide hybrid (IPH), we investigated the effect of nucleic acids with different lengths and sequence variations on AMLO.

Minimalist Design of an Intrinsically Disordered Protein-Mimicking Scaffold for an Artificial Membraneless Organelle.

Liquid-liquid phase separation (LLPS) is an emerging and universal mechanism for intracellular organization, particularly, by forming membraneless organelles (MLOs) hosting intrinsically disordered proteins (IDPs) as scaffolds. Genetic engineering is generally applied to reconstruct IDPs harboring over 100 amino acid residues. Here, we report the first design of synthetic hybrids consisting of short oligopeptides of fewer than 10 residues as "stickers" and dextran as a "spacer" to recapitulate the characteristics of IDPs, as exemplified by the multivalent FUS protein.

Droplet-Based Microfluidic Synthesis of Hydrogel Microparticles via Click Chemistry-Based Cross-Linking for the Controlled Release of Proteins.

Hydrogel microparticles (HMPs) have been widely applied in biological, pharmacologic, and biomedical industries due to their versatility. Particle size is a paramount factor for controlling drug release profiles from HMPs. Conventional fabrication methods such as bulk emulsion, coacervation, and spray drying do not offer a precise size control and high reproducibility, which may compromise the utility of HMPs for controlled release.

A bioinspired synthetic soft hydrogel for the treatment of dry eye.

Natural soft hydrogels are unique elastic soft materials utilized by living organisms for protecting delicate tissues. Under a theoretical framework derived from the Blob model, we chemically crosslinked high molecular weight hyaluronic acid at a concentration close to its overlap concentration (*), and created synthetic soft hydrogels that exhibited unique rheological properties similar to a natural soft hydrogel: being dominantly elastic under low shear stress while being viscous when the stress is above a small threshold. We explored a potential application of the hyaluronic acid-based soft hydrogel as a long-acting ocular surface lubricant and evaluated its therapeutic effects for dry eye.

The effect of polysaccharide-based hydrogels on the response of antigen-presenting cell lines to immunomodulators.

Hydrogel presents as foreign material to the host and participates in immune responses, which skew the biofunctions of immunologic loads (antigen and adjuvants) during DC priming. This study aims to investigate the effect of the hydrogel made from different polysaccharides on macrophage (RAW264.7) activation and DC (JAWSII) modulation.

Altered Peptide Self-Assembly and Co-Assembly with DNA by Modification of Aromatic Residues.

Aromatic residues are widely used as building blocks for driving self-assemblies in natural and designer biomaterials. The noncovalent interactions involving aromatic rings determine proteins' structure and biofunction. Here, we studied the effects of changes in the proximity of the aromatic rings in a self-assembling peptide for modulating interactions involving the aromatic residues.

Controllable multi-phase protein release from in-situ hydrolyzable hydrogel.

Using hydrogels to control the long-term release of protein remains challenging, especially for in-situ forming formulations. The uncontrollable burst release in the initial phase, the halted release in the subsequent phase, and the undesired drug dumping at the late stage are some obstacles hydrogel-based depots commonly encounter. In this study, we report hydrolyzable dextran-based hydrogels crosslinked by Michael addition to demonstrate a systematic solution to solve these problems.

Enhanced Delivery of siRNA to Retinal Ganglion Cells by Intravitreal Lipid Nanoparticles of Positive Charge.

RNAi therapy has been developed and explored for treating retinal conditions since last decades. The progression of retinal diseases including the age-related macular degeneration and glaucoma is associated with the malfunction of specific retinal cells. Therefore, to deliver therapeutic RNAi to selective retinal tissues with desired gene downregulation is crucial for the treatment of retinal diseases RNAi therapy.

Dual-Diffusivity Stochastic Model for Macromolecule Release from a Hydrogel.

A three-dimensional model has been developed to describe the multiphase release of macromolecular drugs encapsulated in a hydrogel. The heterogeneity of network mesh size was considered by assigning varying diffusion coefficients to the network lattices randomly. Using a stochastic approach, the random nature of diffusion of drug molecules was captured within the network.

The synergy of chemical immobilization and electrical orientation of T4 bacteriophage on a micro electrochemical sensor for low-level viable bacteria detection via Differential Pulse Voltammetry.

In this work, a wild-type T4 bacteriophage based micro electrochemical sensor (T4B-MES) was developed for specific and sensitive detection of viable pathogenic bacteria. Recently, bacteriophage has been widely applied as recognition elements for bacteria detection due to its low cost, high stability and specificity. Firstly, a systematic study was proposed in this paper to investigate the synergy of externally applied electric field and chemical functionalization on phage immobilization, involving several key factors such as Debye length.

Phage-based Electrochemical Sensors: A Review.

Phages based electrochemical sensors have received much attention due to their high specificity, sensitivity and simplicity. Phages or bacteriophages provide natural affinity to their host bacteria cells and can serve as the recognition element for electrochemical sensors. It can also act as a tool for bacteria infection and lysis followed by detection of the released cell contents, such as enzymes and ions.

Nanoassembly of Oligopeptides and DNA Mimics the Sequential Disassembly of a Spherical Virus.

Protein subunits of a low aspect ratio (width over length) with stimuli-responsiveness are hallmark building blocks of spherical viruses. The interaction of these repeating subunits enables hierarchical assembly for genome packaging and sequential disassembly for optimal genome release. Here, we mimicked these features and constructed a functional spherical artificial virus.