Macroscopic Supramolecular Assembly Strategy to Construct 3D Biocompatible Microenvironments with Site-Selective Cell Adhesion

Chiral nanosystem and chiral supraparticles for drug delivery: an expert opinion

INTRODUCTION

Chiral nanocarriers enhance therapeutic efficacy by improving in vivo stability and cellular uptake. Chemical functionalization reduces cytotoxicity, resulting in favorable biocompatibility. Nanoparticles self-assemble into supraparticles, enhancing drug delivery through improved retention and drug loading.

AREA COVERED

This review covers chiral nanostructures and chiral supraparticles, and their applications in drug delivery and various healthcare applications.

EXPERT OPINION

The chirality of biomaterials is crucial for advancing nanomedicine. Chiral nanosystem enhance drug delivery by interacting selectively with biological molecules, improving their specificity and efficacy. This reduces off-target effects and improves therapeutic outcomes. Research has focused on cellular uptake and elimination to ensure safety, and chiral nanomaterials also show promise in optical sensing and gene editing. Their biocompatibility and ability to self-assemble into supraparticles may make them ideal for drug delivery systems.

Precise and selective macroscopic assembly of a dual lock-and-key structured hydrogel

Macroscopic assembly offers immense potential for constructing complex systems due to the high design flexibility of the building blocks. In such assembly systems, hydrogels are promising candidates for building blocks due to their versatile chemical compositions and ease of property tuning. However, two major challenges must be addressed to facilitate application in a broader context: the precision of assembly and the quantity of orthogonally matching pairs must both be increased. Although previous studies have attempted to address these challenges, none have successfully dealt with both simultaneously. Here, we propose topology-based design criteria for the selective assembly of hydrogel building blocks. By introducing the dual lock-and-key structures, we demonstrate highly precise assembly exclusively between the matching pairs. We establish principles for selecting multiple orthogonally matching pairs and achieve selective assembly involving simple one-to-one matching and complex assemblies with multiple orthogonal matching points. Moreover, by harnessing hydrogel tunability and the abundance of matching pairs, we synthesize complementary single-stranded structures for programmable assembly and successfully assemble them in the correct order. Finally, we demonstrate a hydrogel-based self-assembled logic gate system, including a YES gate, an OR gate, and an AND gate. The output is generated only when the corresponding inputs are provided according to each logic.

Polyelectrolyte chain conformation matters in macroscopic supramolecular self-assembly

We demonstrate molecular-conformation-dependent macroscopic supramolecular self-assembly (MSA) driven by electrostatic interactions. Evidence from single molecular force spectroscopy reveals that polyelectrolytes modified on MSA component surfaces make MSA possible with a loop conformation, while those with a flat conformation lead to no assembly, which is attributed to distinct molecular mobility. We believe that this finding is also applicable in fundamental phenomena such as surface adsorption and adhesion regarding polymers.

Influence of a Composite Polylysine-Polydopamine-Quaternary Ammonium Salt Coating on Titanium on Its Ostogenic and Antibacterial Performance

Thin oxide layers form easily on the surfaces of titanium (Ti) components, with thicknesses of <100 nm. These layers have excellent corrosion resistance and good biocompatibility. Ti is susceptible to bacterial development on its surface when used as an implant material, which reduces the biocompatibility between the implant and the bone tissue, resulting in reduced osseointegration. In the present study, Ti specimens were surface-negatively ionized using a hot alkali activation method, after which polylysine and polydopamine layers were deposited on them using a layer-by-layer self-assembly method, then a quaternary ammonium salt (QAS) (EPTAC, DEQAS, MPA-N⁺) was grafted onto the surface of the coating. In all, 17 such composite coatings were prepared. Against Escherichia coli and Staphylococcus aureus, the bacteriostatic rates of the coated specimens were 97.6 ± 2.0% and 98.4 ± 1.0%, respectively. Thus, this composite coating has the potential to increase the osseointegration and antibacterial performance of implantable Ti devices.

Robust Electrostatically Interactive Hydrogel Coatings for Macroscopic Supramolecular Assembly via Rapid Wet Adhesion

A macroscopic supramolecular assembly (MSA) refers to non-covalent interactions between building blocks over a micrometer scale, which provides insights into bio-/wet adhesion, self-healing, and so on and new fabrication strategies to heterogeneous structures and bio-scaffolds. The key to realize the MSA of rigid materials is pre-modifying a compliant coating known as a "flexible spacing coating" beneath the interactive moieties. However, available coatings are limited to polyelectrolyte multilayers with shortcomings of tedious fabrication, weak adhesion to substrates, susceptibility to external reagents, and so on. Here, we develop a facile method to induce a new "flexible spacing coating" of a poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogel with electrostatic interactions to achieve MSA of diverse rigid materials (quartz, metal, rubber, and plastics). Selective self-assembly of positive-negative charged surfaces is observed by the naked eye under 3 min of shaking in water, providing strategies to rapid wet adhesion. The interfacial binding force between positive-negative interacted surfaces is 1018.1 ± 299.2 N/m², which is over two magnitudes larger than that of control groups, that is, positive-positive (24.4 ± 10.0 N/m²) and negative-negative (67.5 ± 16.7 N/m²) interacted surfaces. In situ force measurements and control experiments of identically charged building blocks have strongly supported the improved binding strength and chemical selectivity between interactive building blocks. The coating is advantageous with a simple fabrication, strong adhesion to materials, robust solvent tolerance to assembly solutions, and feasibility of photo-patterning. We envision that the above strategy would broaden the material choices of flexible spacing coatings for efficient MSA and new methods for rapid interfacial adhesion.

Macroscopic Supramolecular Assembly of Rigid Building Blocks Facilitated by Layer-By-Layer Assembled Microgel Film

Macroscopic supramolecular assembly (MSA) of building blocks larger than 1 μm provides new methodology for fabrication of functional supramolecular materials and a platform for mechanism investigation of interfacial phenomena. Most reports on MSA are restricted to soft hydrogels, and supramolecular groups can be directly integrated into a hydrogel matrix to generate sufficient attraction for maintaining macroscopic assemblies. For non-hydrogel stiff building blocks, two layer-by-layer modification processes consisting of flexible spacing coating and additional interacting groups are necessary to enable MSA, which is laborious and time-consuming. Approaches for highly efficient MSA based on flexible spacing coating are desired. In this work, MSA of polydimethylsiloxane (PDMS) building blocks is demonstrated by inducing microgel films that serve as both flexible spacing coating and surface functional groups, thus avoiding a two-step LbL modification process. By the varying bilayer number of microgel films, the MSA probability of modified PDMS increases from 54% at 3 bilayers to 100% at 6 bilayers. Control experiments and in situ force measurement strongly support the obtained MSA results and verify the dominant role of the microgel film as a flexible spacing coating and a supramolecularly interactive layer in achieving MSA. Moreover, the underlying mechanism is interpreted as low Young's modulus microgel films rendering surface groups highly mobile to enhance the multivalent interfacial binding. Taken together, this work has demonstrated the feasibility of MSA of rigid building blocks assisted by microgel films as flexible spacing coating and supramolecularly interactive layer simultaneously, which may extend the application fields of microgel materials to interfacial adhesion and advanced manufacturing with MSA methodology.

Chiral-engineered supraparticles: Emerging tools for drug delivery

The handedness of chiral-engineered supraparticles (CE-SPs) influences their interactions with cells and proteins, as evidenced by the increased penetration of breast, cervical, and myeloma cell membranes by d-chirality-coordinated SPs. Quartz crystal dissipation and isothermal titration calorimetry have been used to investigate such chiral-specific interactions. d-SPs are more thermodynamically stable compared with l-SPs in terms of their adhesion. Proteases and other endogenous proteins can be shielded by the opposite chirality of d-SPs, resulting in longer half-lives. Incorporating nanosystems with d-chirality increases uptake by cancer cells and prolongs in vivo stability, demonstrating the importance of chirality in biomaterials. Thus, as we discuss here, chiral nanosystems could enhance drug delivery systems, tumor markers, and biosensors, among other biomaterial-based technologies, by allowing for better control over their features.

Three-Dimensional Printable Enzymatically Active Plastics

Here, we describe a facile route to the synthesis of enzymatically active highly fabricable plastics, where the enzyme is an intrinsic component of the material. This is facilitated by the formation of an electrostatically stabilized enzyme-polymer surfactant nanoconstruct, which, after lyophilization and melting, affords stable macromolecular dispersions in a wide range of organic solvents. A selection of plastics can then be co-dissolved in the dispersions, which provides a route to bespoke 3D enzyme plastic nanocomposite structures using a wide range of fabrication techniques, including melt electrowriting, casting, and piston-driven 3D printing. The resulting constructs comprising active phosphotriesterase (arPTE) readily detoxify organophosphates with persistent activity over repeated cycles and for long time periods. Moreover, we show that the protein guest molecules, such as arPTE or sfGFP, increase the compressive Young's modulus of the plastics and that the identity of the biomolecule influences the nanomorphology and mechanical properties of the resulting materials. Overall, we demonstrate that these biologically active nanocomposite plastics are compatible with state-of-the-art 3D fabrication techniques and that the methodology could be readily applied to produce robust and on-demand smart nanomaterial structures.

Photo-Controlled Macroscopic Self-Assembly Based on Photo-Switchable Hetero-Complementary Quadruple Hydrogen Bonds

A photo-switchable hetero-complementary quadruple H-bonding array, which consists of an azobenzene-derived ureidopyrimidinone (UPy) module (Azo-UPy) and a nonphotoactive diamidonaphthyridine (DAN) derivative (Napy-1), is constructed based on a reversible photo-locking approach. Upon UV (390 nm)/Vis (460 nm) light irradiations, photo-switchable quadruple H-bonded dimerization between Azo-UPy and Napy-1 can be achieved with exhibiting 4.8×10⁴ -fold differences in binding strength (ON/OFF ratios). Furthermore, smart polymeric gels with unique photo-controlled macroscopic self-assembly behavior can be fabricated by introducing such quadruple H-bonding array as photo-regulable noncovalent interfacial connections.

Codes in Code: AIE Supramolecular Adhesive Hydrogels Store Huge Amounts of Information

With the continuous advancement of information technology, the requirements for the information storage capacity of materials are getting higher and higher. However, information code materials usually only store a single piece of information. In order to improve their storage capacity, aggregation-induced emission (AIE) supramolecular adhesive hydrogels with different fluorescent colors are prepared, and a "Codes in Code" method is used to demonstrate the storage capacity for large amounts of information. Four kinds of poly(vinyl alcohol) (PVA) supramolecular hydrogels with different fluorescent colors are prepared; based on the hydrogen bonds on the hydrogel surface, these hydrogels can be assembled into a hydrogel, G5, which shows multiple fluorescent colors under the irradiation of UV light. When many 1D barcode patterns or/and 2D code patterns are incorporated into G5, not only a kind of 3D information but also plenty of 1D or/and 2D information can be stored. Therefore, the information codes prepared by the "Codes in Code" method can store a large amount of information.

Photopolymerization strategy for the preparation of small-diameter artificial blood vessels with micro-nano structures on the inner wall

Although large diameter vessels made of polyurethane materials have been widely used in clinical practice, the biocompatibility and long-term patency of small diameter artificial vessels have not been well addressed. Any technological innovation and advancement in small-diameter artificial blood vessels is of great interest to the biomedical field. Here a novel technique is used to produce artificial blood vessels with a caliber of less than 6 mm and a wall thickness of less than 0.5 mm by rotational exposure, and to form a bionic inner wall with a periodically micro-nano structure inside the tube by laser double-beam interference. The polyethylene glycol diacrylate used is a widely recognized versatile biomaterial with good hydrophilicity, biocompatibility and low cytotoxicity. The effect of the bionic structure on the growth of hepatocellular carcinoma cells and human umbilical vein endothelial cells was investigated, and it was demonstrated that the prepared vessels with the bionic structure could largely promote the endothelialization process of the cells inside them.

Precise macroscopic supramolecular assembly of photopatterned hydrogels

Here we demonstrate that a precise macroscopic supramolecular assembly (MSA) can be achieved using a surface photopatterning strategy. The electrostatic interaction of the photopatterned polyelectrolytes drives hydrogel cuboids to form a stable MSA on a millimeter scale and the spatial controllability of light enables the hydrogels to be assembled into complex supramolecular architectures.