Introduction to nanocoatings produced by layer-by-layer (LbL) self-assembly

Layer-by-Layer Assembly of Renal-Targeted Polymeric Nanoparticles for Robust Arginase-2 Knockdown and Contrast-Induced Acute Kidney Injury Prevention

The mitochondrial enzyme arginase-2 (Arg-2) is implicated in the pathophysiology of contrast-induced acute kidney injury (CI-AKI). Therefore, Arg-2 represents a candid target for CI-AKI prevention. Here, layer-by-layer (LbL) assembled renal-targeting polymeric nanoparticles are developed to efficiently deliver small interfering RNA (siRNA), knockdown Arg-2 expression in renal tubules, and prevention of CI-AKI is evaluated. First, near-infrared dye-loaded poly(lactic-co-glycolic acid) (PLGA) anionic cores are electrostatically coated with cationic chitosan (CS) to facilitate the adsorption and stabilization of Arg-2 siRNA. Next, nanoparticles are coated with anionic hyaluronan (HA) to provide protection against siRNA leakage and shielding against early clearance. Sequential electrostatic layering of CS and HA improves loading capacity of Arg-2 siRNA and yields LbL-assembled nanoparticles. Renal targeting and accumulation is enhanced by modifying the outermost layer of HA with a kidney targeting peptide (HA-KTP). The resultant kidney-targeting and siRNA loaded nanoparticles (PLGA/CS/HA-KTP siRNA) exhibit proprietary accumulation in kidneys and proximal tubular cells at 24 h post-tail vein injection. In iohexol-induced in vitro and in vivo CI-AKI models, PLGA/CS/HA-KTP siRNA delivery alleviates oxidative and nitrification stress, and rescues mitochondrial dysfunction while reducing apoptosis, thereby demonstrating a robust and satisfactory therapeutic effect. Thus, PLGA/CS/HA-KTP siRNA nanoparticles offer a promising candidate therapy to protect against CI-AKI.

One-Pot Self-Assembly of Sequence-Controlled Mesoporous Heterostructures via Structure-Directing Agents

Multimaterial heterostructures have led to characteristics surpassing the individual components. Nature controls the architecture and placement of multiple materials through biomineralization of nanoparticles (NPs); however, synthetic heterostructure formation remains limited and generally departs from the elegance of self-assembly. Here, a class of block polymer structure-directing agents (SDAs) are developed containing repeat units capable of persistent (covalent) NP interactions that enable the direct fabrication of nanoscale porous heterostructures, where a single material is localized at the pore surface as a continuous layer. This SDA binding motif (design rule 1) enables sequence-controlled heterostructures, where the composition profile and interfaces correspond to the synthetic addition order. This approach is generalized with 5 material sequences using an SDA with only persistent SDA-NP interactions ("P-NP1-NP2"; NPi = TiO2, Nb2O5, ZrO2). Expanding these polymer SDA design guidelines, it is shown that the combination of both persistent and dynamic (noncovalent) SDA-NP interactions ("PD-NP1-NP2") improves the production of uniform interconnected porosity (design rule 2). The resulting competitive binding between two segments of the SDA (P- vs D-) requires additional time for the first NP type (NP1) to reach and covalently attach to the SDA (design rule 3). The combination of these three design rules enables the direct self-assembly of heterostructures that localize a single material at the pore surface while preserving continuous porosity.

A Wood-Derived Periosteum for Spatiotemporal Drug Release: Boosting Bone Repair through Anisotropic Structure and Multiple Functions

Existing artificial periostea face many challenges, including difficult-to-replicate anisotropy in mechanics and structure, poor tissue adhesion, and neglected synergistic angiogenesis and osteogenesis. Here, inspired by natural wood (NW), a wood-derived elastic artificial periosteum is developed to mimic the structure and functions of natural periosteum, which combines an elastic wood (EW) skeleton, a polydopamine (PDA) binder layer, and layer-by-layer (LBL) biofunctional layers. Specifically, EW derived from NW is utilized as the anisotropic skeleton of artificial periosteum to guide cell directional behaviors, moreover, it also shows a similar elastic modulus and flexibility to natural periosteum. To further enhance its synergistic angiogenesis and osteogenesis, surface LBL biofunctional layers are designed to serve as spatiotemporal release platforms to achieve sequential and long-term release of pamidronate disodium (PDS) and deferoxamine (DFO), which are pre-encapsulated in chitosan (CS) and hyaluronic acid (HA) solutions, respectively. Furthermore, the combined effect of PDA coating and LBL biofunctional layers enables the periosteum to tightly adhere to damaged bone tissue. More importantly, this novel artificial periosteum can boost angiogenesis and bone formation in vitro and in vivo. This study opens up a new path for biomimetic design of artificial periosteum, and provides a feasible clinical strategy for bone repair.

Chitosan/bovine serum albumin layer-by-layer assembled particles for non-invasive inhaled drug delivery to the lungs

Layer-by-Layer (LbL) assembly of polyelectrolytes on a solid core particle is a well-established technique used to deliver drugs, proteins, regenerative medicines, combinatorial therapy, etc. It is a multifunctional delivery system which can be engineered using various core template particles and coating polymers. This study reports the development and in-vitro evaluation of LbL assembled particles for non-invasive inhaled delivery to the lungs. The LbL assembled particles were prepared by successively coating polyelectrolyte macromolecules, glycol chitosan and bovine serum albumin on 0.5- and 4.5-μm polystyrene particles. The LbL assembly of polyelectrolytes was confirmed by reversible change in zeta potential and sequential increase in the particle size after accumulation of the layer. The prepared LbL particles were further assessed for aerodynamic properties using two distinct nebulizers, and toxicity assessment in normal lung cells. The in-vitro aerosolization study performed using next generation impactor coupled with Pari LC Plus and Aeroeclipse nebulizer showed that both the LbL assembled 0.5 and 4.5-μm particles had MMAD <5 μm confirming suitable aerodynamic properties for non-invasive lung delivery. The in-vitro cytotoxicity, and TEER integrity following treatment with the LbL assembled particles in normal lung epithelial and fibroblasts showed no significant cytotoxicity rendering the LbL assembled particles safe. This study extends the efficiency of LbL assembled particles for novel applications towards delivery of small and large molecules into the lungs.

Advancements in Polymer-Assisted Layer-by-Layer Fabrication of Wearable Sensors for Health Monitoring

Recent advancements in polymer-assisted layer-by-layer (LbL) fabrication have revolutionized the development of wearable sensors for health monitoring. LbL self-assembly has emerged as a powerful and versatile technique for creating conformal, flexible, and multi-functional films on various substrates, making it particularly suitable for fabricating wearable sensors. The incorporation of polymers, both natural and synthetic, has played a crucial role in enhancing the performance, stability, and biocompatibility of these sensors. This review provides a comprehensive overview of the principles of LbL self-assembly, the role of polymers in sensor fabrication, and the various types of LbL-fabricated wearable sensors for physical, chemical, and biological sensing. The applications of these sensors in continuous health monitoring, disease diagnosis, and management are discussed in detail, highlighting their potential to revolutionize personalized healthcare. Despite significant progress, challenges related to long-term stability, biocompatibility, data acquisition, and large-scale manufacturing are still to be addressed, providing insights into future research directions. With continued advancements in polymer-assisted LbL fabrication and related fields, wearable sensors are poised to improve the quality of life for individuals worldwide.

Overcoming the Low-Stability Bottleneck in the Clinical Translation of Liposomal Pressurized Metered-Dose Inhalers: A Shell Stabilization Strategy Inspired by Biomineralization

Currently, several types of inhalable liposomes have been developed. Among them, liposomal pressurized metered-dose inhalers (pMDIs) have gained much attention due to their cost-effectiveness, patient compliance, and accurate dosages. However, the clinical application of liposomal pMDIs has been hindered by the low stability, i.e., the tendency of the aggregation of the liposome lipid bilayer in hydrophobic propellant medium and brittleness under high mechanical forces. Biomineralization is an evolutionary mechanism that organisms use to resist harsh external environments in nature, providing mechanical support and protection effects. Inspired by such a concept, this paper proposes a shell stabilization strategy (SSS) to solve the problem of the low stability of liposomal pMDIs. Depending on the shell material used, the SSS can be classified into biomineralization (biomineralized using calcium, silicon, manganese, titanium, gadolinium, etc.) biomineralization-like (composite with protein), and layer-by-layer (LbL) assembly (multiple shells structured with diverse materials). This work evaluated the potential of this strategy by reviewing studies on the formation of shells deposited on liposomes or similar structures. It also covered useful synthesis strategies and active molecules/functional groups for modification. We aimed to put forward new insights to promote the stability of liposomal pMDIs and shed some light on the clinical translation of relevant products.

Recent Development and Applications of Polydopamine in Tissue Repair and Regeneration Biomaterials

The various tissue damages are a severe problem to human health. The limited human tissue regenerate ability requires suitable biomaterials to help damage tissue repair and regeneration. Therefore, many researchers devoted themselves to exploring biomaterials suitable for tissue repair and regeneration. Polydopamine (PDA) as a natural and multifunctional material which is inspired by mussel has been widely applied in different biomaterials. The excellent properties of PDA, such as strong adhesion, photothermal and high drug-loaded capacity, seem to be born for tissue repair and regeneration. Furthermore, PDA combined with different materials can exert unexpected effects. Thus, to inspire researchers, this review summarizes the recent and representative development of PDA biomaterials in tissue repair and regeneration. This article focuses on why apply PDA in these biomaterials and what PDA can do in different tissue injuries.

pH stimulus-responsive hybrid nanoparticles: A system designed for follicular delivery of brazilian plant-derived 5-alpha-reductase enzyme inhibitors

The 5-alpha-reductase enzyme, present in pilosebaceous units, plays a crucial role in the appearance of cutaneous hyperandrogenism manifestations (hirsutism, acne, and androgenetic alopecia). Its inhibition is an excellent strategy to reverse these conditions. Given the limitations of existing treatments, with transient effects and delayed therapeutic response, as well as the possibility of causing undesirable side effects, this study sought to develop new drug delivery systems to overcome these limitations. In other words, innovative stimuli-responsive hybrid nanoparticles were synthesized using silica/natural polysaccharides, encapsulating 5-alpha-reductase enzyme inhibitors derived from the plant Stryphnodendron adstringens (Mart.) Coville (commonly known as 'Barbatimão'). Silica core was synthesized by the modified Stöber method. The pH responsive polysaccharides used to coat the porous silica cores were chitosan, and sodium alginate, this coating was carried out using the Layer-by-Layer technique. The hybrid nanoparticles were characterized at molecular and physical-chemical levels. Furthermore, encapsulation efficiency, pH-dependent release behavior, and cytotoxicity were evaluated. Amorphous mesoporous structure with adequate size for follicular delivery (between 300 and 600 nm) in addition to effective phytocompound loading capacity, above 80 % was obtained. Based on the release studies, it was possible to observe pH responsiveness. The ethyl acetate fraction (EAF) obtained from "Barbatimão" bark extract was released in a controlled and more efficient manner by the alginate-coated nanoparticle (SNP_EAF_SA) at pH 7.4, which corresponds to the pH at the deepest area of hair follicles. Furthermore, SNP_EAF_SA proved to be less cytotoxic compared to EAF and chitosan-coated hybrid nanoparticles (SNP_EAF_CH). Characterization, release, and cytotoxicity results indicate that SNP_EAF_SA is a promising system for on-demand follicular delivery of antiandrogenic actives contained in EAF.

Nano-platform Strategies of Herbal Components for the Management of Rheumatoid Arthritis: A Review on the Battle for Next-Generation Formulations

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that initially affects small joints and then spreads to the bigger joints. It also affects other organs of the body such as lungs, eyes, kidneys, heart, and skin. In RA, there is destruction of cartilage and joints, and ligaments and tendons become brittle. Damage to the joints leads to abnormalities and bone degradation, which may be quite painful for the patient.

METHOD

The nano-carriers such as liposomes, phytosomes, nanoparticles, microcapsules, and niosomes are developed to deliver the encapsulated phytoconstituents to targeted sites for the better management of RA.

RESULTS

The phytoconstituents loaded nano-carriers have been used in order to increase bioavailability, stability and reduce the dose of an active compound. In one study, the curcumin-loaded phytosomes increase the bioavailability of curcumin and also provides relief from RA symptoms. The drug-loaded nano-carriers are the better option for the management of RA.

CONCLUSION

In conclusion, there are many anti-arthritic herbal and synthetic medicine available in the market that are currently used in the treatment of RA. However, chronic use of these medications may result in a variety of side effects. Because therapy for RA is frequently necessary for the rest of ones life. The use of natural products may be a better option for RA management. These phytoconstituents, however, have several disadvantages, including limited bioavailability, low stability, and the need for a greater dosage. These problems can be rectified by using nano-technology.

A three-dimensional composite film-modified electrode based on polyoxometalates and ionic liquid-decorated carbon nanotubes for the determination of L-tyrosine in food

A stable and innovative composite film-modified electrode based on Dawson polyoxometalates H8P2Mo16V2O62 (P2Mo16V2) and ionic liquid (BMIMBr)-decorated carbon nanotubes, annotated as PEI/(P2Mo16V2/BMIMBr-CNTs)8, has been constructed by using the layer-by-layer self-assembly (LBL) method for the determination of L-tyrosine. The combination of three active components not only offers higher conductivity to facilitate rapid electron transfer, but also avoids the accumulation of P2Mo16V2 to expand the contact area and increase the reactive active sites. The modified electrode exhibits outstanding sensing performance for determination of Tyr with wide linear determination range of 5.8×10-7 M ~ 1.2×10-4 M, low determination limit of 1.7×10-7M (S/N=3), high selectivity for common interferences, and excellent stability at the potential of +0.78 V (vs. Ag/AgCl (3 M KCl)). The relative standard deviation (RSD) of 4.3% for five groups of parallel experiments shows the satisfactory repeatability of PEI/(P2Mo16V2/BMIMBr-CNTs)8. In addition, for determination of Tyr, the PEI/(P2Mo16V2/BMIMBr-CNTs)8 shows good recoveries of 98.8-99.8% in meat floss, which can be feasible in practical application.

Conditions for the stable adsorption of lipid monolayers to solid surfaces

Lipid monolayers are ubiquitous in biological systems and have multiple roles in biotechnological applications, such as lipid coatings that enhance colloidal stability or prevent surface fouling. Despite the great technological importance of surface-adsorbed lipid monolayers, the connection between their formation and the chemical characteristics of the underlying surfaces has remained poorly understood. Here, we elucidate the conditions required for stable lipid monolayers nonspecifically adsorbed on solid surfaces in aqueous solutions and water/alcohol mixtures. We use a framework that combines the general thermodynamic principles of monolayer adsorption with fully atomistic molecular dynamics simulations. We find that, very universally, the chief descriptor of adsorption free energy is the wetting contact angle of the solvent on the surface. It turns out that monolayers can form and remain thermodynamically stable only on substrates with contact angles above the adsorption contact angle, θads. Our analysis establishes that θads falls into a narrow range of around 60∘-70∘ in aqueous media and is only weakly dependent on the surface chemistry. Moreover, to a good approximation, θads is roughly determined by the ratio between the surface tensions of hydrocarbons and the solvent. Adding small amounts of alcohol to the aqueous medium lowers θads and thereby facilitates monolayer formation on hydrophilic solid surfaces. At the same time, alcohol addition weakens the adsorption strength on hydrophobic surfaces and results in a slowdown of the adsorption kinetics, which can be useful for the preparation of defect-free monolayers.

Layer-by-Layer Nanoassemblies for Vaccination Purposes

In recent years, the availability of effective vaccines has become a public health challenge due to the proliferation of different pandemic outbreaks which are a risk for the world population health. Therefore, the manufacturing of new formulations providing a robust immune response against specific diseases is of paramount importance. This can be partially faced by introducing vaccination systems based on nanostructured materials, and in particular, nanoassemblies obtained by the Layer-by-Layer (LbL) method. This has emerged, in recent years, as a very promising alternative for the design and optimization of effective vaccination platforms. In particular, the versatility and modularity of the LbL method provide very powerful tools for fabricating functional materials, opening new avenues on the design of different biomedical tools, including very specific vaccination platforms. Moreover, the possibility to control the shape, size, and chemical composition of the supramolecular nanoassemblies obtained by the LbL method offers new opportunities for manufacturing materials which can be administered following specific routes and present very specific targeting. Thus, it will be possible to increase the patient convenience and the efficacy of the vaccination programs. This review presents a general overview on the state of the art of the fabrication of vaccination platforms based on LbL materials, trying to highlight some important advantages offered by these systems.

Trends in Bioactive Multilayer Films: Perspectives in the Use of Polysaccharides, Proteins, and Carbohydrates with Natural Additives for Application in Food Packaging

The harmful effects on the environment caused by the indiscriminate use of synthetic plastics and the inadequate management of post-consumer waste have given rise to efforts to redirect this consumption to bio-based economic models. In this sense, using biopolymers to produce materials is a reality for food packaging companies searching for technologies that allow these materials to compete with those from synthetic sources. This review paper focused on the recent trends in multilayer films with the perspective of using biopolymers and natural additives for application in food packaging. Firstly, the recent developments in the area were presented concisely. Then, the main biopolymers used (gelatin, chitosan, zein, polylactic acid) and main methods for multilayer film preparation were discussed, including the layer-by-layer, casting, compression, extrusion, and electrospinning methods. Furthermore, we highlighted the bioactive compounds and how they are inserted in the multilayer systems to form active biopolymeric food packaging. Furthermore, the advantages and drawbacks of multilayer packaging development are also discussed. Finally, the main trends and challenges in using multilayer systems are presented. Therefore, this review aims to bring updated information in an innovative approach to current research on food packaging materials, focusing on sustainable resources such as biopolymers and natural additives. In addition, it proposes viable production routes for improving the market competitiveness of biopolymer materials against synthetic materials.

All-in-one bioactive properties of photothermal nanofibers for accelerating diabetic wound healing

Diabetic wound healing has attracted widespread attention in biomedical engineering. However, the harsh hypoxic microenvironment (HME) comprising high glucose levels, local bleeding, and bacterial infection often leads to the formation of hyperplastic scars, increasing the clinical demand for wound dressings. Here, we report a comprehensive strategy using near-infrared NIR-assisted oxygen delivery combined with the bioactive nature of biopolymers for remodeling the HME. Black phosphorus (BP) nanosheets and hemoglobin (Hb) were self-assembled layerwise onto electrospun poly-l-lactide (PLLA) nanofibers using charged quaternized chitosan (QCS) and hyaluronic acid. BP converts NIR radiation into heat and stimulates Hb to release oxygen in situ. QCS is a hemostatic and broad-spectrum antibacterial material. Moderate BP-derived photothermal therapy can increase the sensitivity of bacteria to QCS. A series of composite wound dressings (coded as PQBH-n) with different numbers of layers were fabricated, and the in vivo diabetic wound healing potentials were tested. The molecular mechanism can be partly attributed to the cytokine-cytokine receptor interaction. Notably, this comprehensive strategy based on NIR-assisted oxygen delivery combined with the bioactive properties of biopolymers is not only applicable for fabricating multifunctional wound dressings but also has a great potential in expanding biomedical engineering fields.

Designing supramolecular self-assembly nanomaterials as stimuli-responsive drug delivery platforms for cancer therapy

Stimuli-responsive nanomaterials have attracted substantial interest in cancer therapy, as they hold promise to deliver anticancer agents to tumor sites in a precise and on-demand manner. Interestingly, supramolecular chemistry is a burgeoning discipline that entails the reversible bonding between components at the molecular and nanoscale levels, and the recent advances in this area offer the possibility to design nanotherapeutics with improved controllability and functionality for cancer therapy. Herein, we provide a comprehensive summary of typical non-covalent interaction modes, which primarily include hydrophobic interaction, hydrogel bonding, host-guest interaction, π-π stacking, and electrostatic interaction. Special emphasis is placed on the implications of these interaction modes to design novel stimuli-responsive drug delivery principles and concepts, aiming to enhance the spatial, temporal, and dosage precision of drug delivery to cancer cells. Finally, future perspectives are discussed to highlight current challenges and future opportunities in self-assembly-based stimuli-responsive drug delivery nanotechnologies for cancer therapy.

Preparation, characterization, and evaluation of flaxseed oil liposomes coated with chitosan and pea protein isolate hydrolysates

The effect of layer-by-layer coating of liposomes with chitosan and pea protein isolate hydrolysates (PPIH) was evaluated. Traditional flaxseed oil liposomes (FL Lipo) were used as a model for comparison to liposomes coated with chitosan and PPIH (FL LipoCP). The potential of PPIH as a coating material was evaluated. Additionally, the influence of chitosan and PPIH on vesicle size and zeta potential of liposomes was investigated. The chitosan layer of liposomes exhibited a loose structure. After the second layer of coating with PPIH, chitosan molecules were rearranged on the liposome surface, leading to a more compact and dense shell structure of liposomes. Electrostatic interactions, hydrogen bonds, and hydrophobic interactions favored the stability of FL LipoCP. Compared to FL Lipo, FL LipoCP displayed higher oxidation stability during storage and a slower release of flaxseed oil during in vitro digestion.

Strategies To Modify the Surface and Bulk Properties of 3D-Printed Solid Scaffolds for Tissue Engineering Applications

3D printing is one of the effective scaffold fabrication techniques that emerged in the 21st century that has the potential to revolutionize the field of tissue engineering. The solid scaffolds developed by 3D printing are still one of the most sought-after approaches for developing hard-tissue regeneration and repair. However, applications of these solid scaffolds get limited due to their poor surface and bulk properties, which play a significant role in tissue integration, loadbearing, antimicrobial/antifouling properties, and others. As a result, several efforts have been directed to modify the surface and bulk of these solid scaffolds. These modifications have significantly improved the adoption of 3D-printed solid scaffolds and devices in the healthcare industry. Nevertheless, the in vivo implant applications of these 3D-printed solid scaffolds/devices are still under development. They require attention in terms of their surface/bulk properties, which dictate their functionality. Therefore, in the current review, we have discussed different 3D-printing parameters that facilitate the fabrication of solid scaffolds/devices with different properties. Further, changes in the bulk properties through material and microstructure modification are also being discussed. After that, we deliberated on the techniques that modify the surfaces through chemical and material modifications. The computational approaches for the bulk modification of these 3D-printed materials are also mentioned, focusing on tissue engineering. We have also briefly discussed the application of these solid scaffolds/devices in tissue engineering. Eventually, the review is concluded with an analysis of the choice of surface/bulk modification based on the intended application in tissue engineering.

Functionally modified halloysite nanotubes for personalized bioapplications

Halloysite nanotubes (HNTs) are naturally aluminosilicate clay minerals that have the benefits of large surface areas, high mechanical properties, easy functionalization, and high biocompatibility, HNTs have been developed as multifunctional nanoplatforms for various bioapplications. Although some reviews have summarized the properties and bioapplications of HNTs, it remains unclear how to functionalize the modifications of HNTs for their personalized bioapplications. In this review, based on the physicochemical properties of HNTs, we summarized the methods of functionalized modifications (surface modification and structure modification) on HNTs. Also, we highlighted their personalized bioapplications (anti-bacterial, anti-inflammatory, wound healing, cancer theranostics, bone regenerative, and biosensing) by stressing on the main roles of HNTs. Finally, we provide perspectives on the future of functionalized modifications of HNTs for docking specific biological applications.

Advances in Multifunctional Bioactive Coatings for Metallic Bone Implants

To fix the bone in orthopedics, it is almost always necessary to use implants. Metals provide the needed physical and mechanical properties for load-bearing applications. Although widely used as biomedical materials for the replacement of hard tissue, metallic implants still confront challenges, among which the foremost is their low biocompatibility. Some of them also suffer from excessive wear, low corrosion resistance, infections and shielding stress. To address these issues, various coatings have been applied to enhance their in vitro and in vivo performance. When merged with the beneficial properties of various bio-ceramic or polymer coatings remarkable bioactive, osteogenic, antibacterial, or biodegradable composite implants can be created. In this review, bioactive and high-performance coatings for metallic bone implants are systematically reviewed and their biocompatibility is discussed. Updates in coating materials and formulations for metallic implants, as well as their production routes, have been provided. The ways of improving the bioactive coating performance by incorporating bioactive moieties such as growth factors, osteogenic factors, immunomodulatory factors, antibiotics, or other drugs that are locally released in a controlled manner have also been addressed.

3D-printed high-density polyethylene scaffolds with bioactive and antibacterial layer-by-layer modification for auricle reconstruction

High-density polyethylene (HDPE) is a promising material for the development of scaffold implants for auricle reconstruction. However, preparing a personalized HDPE auricle implant with favorable bioactive and antibacterial functions to promote skin tissue ingrowth is challenging. Herein, we present 3D-printed HDPE auricle scaffolds with satisfactory pore size and connectivity. The layer-by-layer (LBL) approach was applied to achieve the improved bioactive and antibacterial properties of these 3D printed scaffolds. The HDPE auricle scaffolds were fabricated using an extrusion 3D printing approach, and the individualized macrostructure and porous microstructure were both adjusted by the 3D printing parameters. The polydopamine (pDA) coating method was used to construct a multilayer ε-polylysine (EPL) and fibrin (FIB) modification on the surface of the 3D HDPE scaffold via the LBL self-assembly approach, which provides the bioactive and antibacterial properties. The results of the in vivo experiments using an animal model showed that LBL-coated HDPE auricular scaffolds were able to significantly enhance skin tissue ingrowth and ameliorate the inflammatory response caused by local stress. The results of this study suggest that the combination of the 3D printing technique and surface modification provides a promising strategy for developing personalized implants with biofunctional coatings, which show great potential as a scaffold implant for auricle reconstruction applications.

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3D-printed HDPE auricle scaffolds with suitable pore size and connectivity developed.

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The layer-by-layer (LBL) approach improved bioactive and antibacterial properties.

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The LBL-coated HDPE auricular scaffolds facilitated skin tissue ingrowth in vitro.

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The combination of 3D printing and surface modification is a promising strategy.

Polymer/Enzyme Composite Materials—Versatile Catalysts with Multiple Applications

A significant interest was granted lately to enzymes, which are versatile catalysts characterized by natural origin, with high specificity and selectivity for particular substrates. Additionally, some enzymes are involved in the production of high-valuable products, such as antibiotics, while others are known for their ability to transform emerging contaminates, such as dyes and pesticides, to simpler molecules with a lower environmental impact. Nevertheless, the use of enzymes in industrial applications is limited by their reduced stability in extreme conditions and by their difficult recovery and reusability. Rationally, enzyme immobilization on organic or inorganic matrices proved to be one of the most successful innovative approaches to increase the stability of enzymatic catalysts. By the immobilization of enzymes on support materials, composite biocatalysts are obtained that pose an improved stability, preserving the enzymatic activity and some of the support material’s properties. Of high interest are the polymer/enzyme composites, which are obtained by the chemical or physical attachment of enzymes on polymer matrices. This review highlights some of the latest findings in the field of polymer/enzyme composites, classified according to the morphology of the resulting materials, following their most important applications.

Self-Healing and Shape-Editable Wearable Supercapacitors Based on Highly Stretchable Hydrogel Electrolytes

Shape editability combined with a self-healing capability and long-term cycling durability are highly desirable properties for wearable supercapacitors. Most wearable supercapacitors have rigid architecture and lack the capacity for editability into desirable shapes. Through sandwiching hydrogel electrolytes between two electrodes, a suite of wearable supercapacitors that integrate desirable properties namely: repeated shape editability, excellent self-healing capability, and long-term cycling durability is demonstrated. A strategy is proposed to enhance the long-term cycling durability by utilizing hydrogel electrolytes with unique cross-linking structures. The dynamic crosslinking sites are formed by quadruple H bonds and hydrophobic association, stabilizing the supercapacitors from inorganic ion disruption during charge-discharge processes. The fabricated supercapacitors result in the capacitance retention rates of 99.6% and 95.8% after 5000 and 10 000 charge-discharge cycles, respectively, which are much higher than others reported in the literature. Furthermore, the supercapacitor sheets can be repeatedly processed into various shapes without any capacitance loss. The supercapacitors exhibit a 95% capacitance retention rate after five cutting/self-healing cycles, indicative of their excellent self-healing performance. To demonstrate real-life applicability, the wearable supercapacitors are successfully used to power a light-emitting diode and an electronic watch.

In Vitro Skin Delivery of Griseofulvin by Layer-by-Layer Nanocoated Emulsions Stabilized by Whey Protein and Polysaccharides

Griseofulvin is a poorly water-soluble drug administered orally to treat topical fungal infections of the skin and hair. However, oral administration leads to poor and unpredictable drug pharmacokinetics. Additionally, griseofulvin is unstable in the presence of light. A layer-by-layer (LbL) nanocoating approach was employed to curb these shortcomings by stabilizing emulsions, lyophilized emulsions, and reconstituted emulsions with a layer each of whey protein, and either hyaluronic acid, amylopectin, or alginic acid, which captured the drug. The coating materials are biological, environmentally benign, and plentiful. Photostability studies indicated that the LbL particles afforded 6 h of protection of the topical application. In vitro absorption studies showed that griseofulvin concentrated preferentially in the stratum corneum, with virtually no transdermal delivery. Therefore, LbL-nanocoated emulsions, lyophilized particles, and reconstituted lyophilized emulsions can produce a viable topical delivery system to treat superficial fungal infections.

Polyelectrolyte Multilayered Capsules as Biomedical Tools

Polyelectrolyte multilayered capsules (PEMUCs) obtained using the Layer-by-Layer (LbL) method have become powerful tools for different biomedical applications, which include drug delivery, theranosis or biosensing. However, the exploitation of PEMUCs in the biomedical field requires a deep understanding of the most fundamental bases underlying their assembly processes, and the control of their properties to fabricate novel materials with optimized ability for specific targeting and therapeutic capacity. This review presents an updated perspective on the multiple avenues opened for the application of PEMUCs to the biomedical field, aiming to highlight some of the most important advantages offered by the LbL method for the fabrication of platforms for their use in the detection and treatment of different diseases.

Dextran-based polyelectrolyte multilayers: Effect of charge density on film build-up and morphology

We have studied the growth process of thin polyelectrolyte (PE) films fabricated by the layer-by-layer assembly (LbL) and composed of Dextran sulfate with high (DexS H) and low (DexS L) sulfation rate and poly(allylamine hydrochloride) (PAH). Film growths were monitored by combining Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Surface Plasmon Resonance (SPR) and Atomic Force Microscopy (AFM). Even though, the two films growth up to 10 bilayers, QCM-D showed that polyelectrolyte pairs do not display similar behaviours. (PAH/DexS H) systems lead to linear growth, i.e. amounts deposited increase both for PAH and DexS H, while the PAH/DexS L pair generated zig-zag shaped asymmetric growth. Film water contents were determined by QCM-D solvent exchange and SPR experiments. DexS L contains less water than DexS H and in agreement with the QCM-D dissipation values that suggest the formation of more rigid films in the case of DexS L than DexS H. Surface morphology investigated by AFM display distinct surface patterns since DexS H form thin films with fibril-like morphology covering all the surface while heterogeneous films with "puddle-like" aggregates were imaged in the case of DexS L. Difference of charge compensation and charge neutralisation between both systems likely lead to dissimilar growth mechanisms that are tentatively proposed in this paper.

Organic/Inorganic Self-Assembled Hybrid Nano-Architectures for Cancer Therapy Applications

Since the conceptualization of nanomedicine, numerous nanostructure-mediated drug formulations have progressed into clinical trials for treating cancer. However, recent clinical trial results indicate such kind of drug formulations has a limited improvement on the antitumor efficacy. This is due to the biological barriers associated with those formulations, for example, circulation stability, extravasation efficiency in tumor, tumor penetration ability, and developed multi-drug resistance. When employing for nanomedicine formulations, pristine organic-based and inorganic-based nanostructures have their own limitations. Accordingly, organic/inorganic (O/I) hybrids have been developed to integrate the merits of both, and to minimize their intrinsic drawbacks. In this context, the recent development in O/I hybrids resulting from a self-assembly strategy will be introduced. Through such a strategy, organic and inorganic building blocks can be self-assembled via either chemical covalent bonds or physical interactions. Based on the self-assemble procedure, the hybridization of four organic building blocks including liposomes, micelles, dendrimers, and polymeric nanocapsules with five functional inorganic nanoparticles comprising gold nanostructures, magnetic nanoparticles, carbon-based materials, quantum dots, and silica nanoparticles will be highlighted. The recent progress of these O/I hybrids in advanced modalities for combating cancer, such as, therapeutic agent delivery, photothermal therapy, photodynamic therapy, and immunotherapy will be systematically reviewed.

Anisotropic Particles through Multilayer Assembly

The anisotropy in the shape of polymeric particles has been demonstrated to have many advantages over spherical particulates, including bio-mimetic behavior, shaped-directed flow, deformation, surface adhesion, targeting, motion, and permeability. The layer-by-layer (LbL) assembly is uniquely suited for synthesizing anisotropic particles as this method allows for simple and versatile replication of diverse colloid geometries with precise control over their chemical and physical properties. This review highlights recent progress in anisotropic particles of micrometer and nanometer sizes produced by a templated multilayer assembly of synthetic and biological macromolecules. Synthetic approaches to produce capsules and hydrogels utilizing anisotropic templates such as biological, polymeric, bulk hydrogel, inorganic colloids, and metal-organic framework crystals as sacrificial templates are overviewed. Structure-property relationships controlled by the anisotropy in particle shape and surface are discussed and compared with their spherical counterparts. Advances and challenges in controlling particle properties through varying shape anisotropy and surface asymmetry are outlined. The perspective applications of anisotropic colloids in biomedicine, including programmed behavior in the blood and tissues as artificial cells, nano-motors/sensors, and intelligent drug carriers are also discussed.

Revisiting the Cytotoxicity of Cationic Polyelectrolytes as a Principal Component in Layer-by-Layer Assembly Fabrication

Polycations are an essential part of layer-by-layer (LbL)-assembled drug delivery systems, especially for gene delivery. In addition, they are used for other related applications, such as cell surface engineering. As a result, an assessment of the cytotoxicity of polycations and elucidation of the mechanisms of polycation toxicity is of paramount importance. In this study, we examined in detail the effects of a variety of water-soluble, positively charged synthetic polyelectrolytes on in vitro cytotoxicity, cell and nucleus morphology, and monolayer expansion changes. We have ranked the most popular cationic polyelectrolytes from the safest to the most toxic in relation to cell cultures. 3D cellular cluster formation was disturbed by addition of polyelectrolytes in most cases in a dose-dependent manner. Atomic force microscopy allowed us to visualize in detail the structures of the polyelectrolyte–DNA complexes formed due to electrostatic interactions. Our results indicate a relationship between the structure of the polyelectrolytes and their toxicity, which is necessary for optimization of drug and gene delivery systems.

Polyelectrolyte Multilayers: An Overview on Fabrication, Properties, and Biomedical and Environmental Applications

Polyelectrolyte multilayers are versatile materials that are used in a large number of domains, including biomedical and environmental applications. The fabrication of polyelectrolyte multilayers using the layer-by-layer technique is one of the simplest methods to obtain composite functional materials. The properties of the final material can be easily tuned by changing the deposition conditions and the used building blocks. This review presents the main characteristics of polyelectrolyte multilayers, the fabrication methods currently used, and the factors influencing the layer-by-layer assembly of polyelectrolytes. The last section of this paper presents some of the most important applications of polyelectrolyte multilayers, with a special focus on biomedical and environmental applications.

Layer-by-Layer Assembled Nanostructured Lipid Carriers for CD-44 Receptor-Based Targeting in HIV-Infected Macrophages for Efficient HIV-1 Inhibition

Macrophages act as a cellular reservoir in HIV infection. Elimination of HIV from macrophages has been an unfulfilled dream due to the failure of drugs to reach them. To address this, we developed CD44 receptor-targeted, novel hyaluronic acid (HA)-coated nanostructured lipid carriers (NLCs) of efavirenz via washless layer-by-layer (LbL) assembly of HA and polyallylamine hydrochloride (PAH). NLCs were subjected to TEM analysis, size and zeta potential, in vitro release and encapsulation efficiency studies. The uptake of NLCs in THP-1 cells was studied using fluorescence microscopy and flow cytometry. The anti-HIV efficacy was evaluated using p24 antigen inhibition assay. NLCs were found to be spherical in shape with anionic zeta potential (-23.66 ± 0.87 mV) and 241.83 ± 5.38 nm particle size. NLCs exhibited prolonged release of efavirenz during in vitro drug release studies. Flow cytometry revealed 1.73-fold higher uptake of HA-coated NLCs in THP-1 cells. Cytotoxicity studies showed no significant change in cell viability in presence of NLCs as compared with the control. HA-coated NLCs distributed throughout the cell including cytoplasm, plasma membrane and nucleus, as observed during fluorescence microscopy. HA-coated NLCs demonstrated consistent and significantly higher inhibition (81.26 ± 1.70%) of p24 antigen which was 2.08-fold higher than plain NLCs. The obtained results suggested preferential uptake of HA-coated NLCs via CD44-mediated uptake. The present finding demonstrates that HA-based CD44 receptor targeting in HIV infection is an attractive strategy for maximising the drug delivery to macrophages and achieve effective viral inhibition.

Biofriendly molecular and protein release substrate with integrated piezoelectric motivation and anti-oxidative stress capabilities

Self-powered piezoelectrically active molecular or protein delivery devices have provoked great interest in recent years. However, electric fields used to promote delivery or healing may also induce the redox of water or oxygen to generate reactive oxygen species (ROS) and bring unintended oxidative pressure to the organism and harm biological functions. In addition, protein molecules are easily inactivated in the polymer reservoir matrix due to the pull of strong electrostatic effects. In this study, a multifunctional molecular delivery substrate was fabricated by integrating a piezoelectric-dielectric polymeric substrate, nanoscopic polyelectrolyte films and in-film deposited biomimetic porous CaP coating. The piezoelectric substrate promoted molecular release, and the mineralized coating effectively stored molecules or proteins and simultaneously eliminated ROS, reducing the oxidative stress response generated by oxidative pressure. The present work opens a new way for the development of multifunctional and biofriendly drug delivery devices.

Functional ferrocene polymer multilayer coatings for implantable medical devices: Biocompatible, antifouling, and ROS-sensitive controlled release of therapeutic drugs

Bacterial infections and the formation of biofilms on the surface of implantable medical devices are critical issues that cause device failure. Implantable medical devices, such as drug delivery technologies, offer promising benefits for targeted and prolonged drug release, but a number of common disadvantages arise that include inadequate release and side effects. Organic film coatings for antifouling and drug delivery are expected to overcome these challenges. Ferrocene polymer-based multifunctional multilayer films were prepared to control the reactive oxygen species (ROS)-responsive release of therapeutic agents while maintaining an antifouling effect and improving biocompatibility. Polymers based on ferrocene and polyethylene glycol were prepared by controlling the molar ratio of carboxylate and amine groups. Layer-by-layer deposition was optimized to achieve the linear growth and self-assembly of dense and stable films. Outstanding anti-biofilm activity (~91% decrease) could be achieved and the films were found to be blood compatible. Importantly, the films effectively incorporated hydrophobic drugs and exhibited dual-responsive drug release at low pH and under ROS conditions at physiological pH. Drug delivery to MCF-7 breast cancer cells was achieved using a Paclitaxel loaded film, which exhibited an anticancer efficacy of 62%. STATEMENT OF SIGNIFICANCE: Healthcare associated infection is caused by the formation of a biofilm by bacteria on the surface of a medical device. In order to solve this, extensive research has been conducted on many coating technologies. Also, a method of chemical treatment by releasing the drug when it enters the body by loading the drug into the coating film is being studied. However, there is still a lack of technology that can achieve both functions of preventing biofilm production and drug delivery. Therefore, in this study, a multilayer thin film that supports drug and inhibits biofilm formation was prepared through Layer-by-Layer coating of a polymer containing PEG to prevent adsorption. As such, it helps the design of multifunctional coatings for implantable medical devices.

Review of Contemporary Self-Assembled Systems for the Controlled Delivery of Therapeutics in Medicine

The novel and unique design of self-assembled micro and nanostructures can be tailored and controlled through the deep understanding of the self-assembly behavior of amphiphilic molecules. The most commonly known amphiphilic molecules are surfactants, phospholipids, and block copolymers. These molecules present a dual attraction in aqueous solutions that lead to the formation of structures like micelles, hydrogels, and liposomes. These structures can respond to external stimuli and can be further modified making them ideal for specific, targeted medical needs and localized drug delivery treatments. Biodegradability, biocompatibility, drug protection, drug bioavailability, and improved patient compliance are among the most important benefits of these self-assembled structures for drug delivery purposes. Furthermore, there are numerous FDA-approved biomaterials with self-assembling properties that can help shorten the approval pathway of efficient platforms, allowing them to reach the therapeutic market faster. This review focuses on providing a thorough description of the current use of self-assembled micelles, hydrogels, and vesicles (polymersomes/liposomes) for the extended and controlled release of therapeutics, with relevant medical applications. FDA-approved polymers, as well as clinically and commercially available nanoplatforms, are described throughout the paper.

Antiproliferative drug-loaded multi-functionalized intraocular lens for reducing posterior capsular opacification

Posterior capsule opacification (PCO) is one of the most frequent complications in cataract surgery and likely to cause the second loss of vision. Proliferation and migration of postoperative remnants of lens epithelial cells (LECs) on the implanted intraocular lens (IOL) are the leading causes of PCO. Antiproliferative drugs can be an effective solution but also possess some problems including sudden release and accompanying adverse effects to surrounding normal tissues, which greatly limit the clinical trials. In this study, an antiproliferative drug Paclitaxel (Pac) -sustained released hyaluronic acid (HA) and chitosan (CHI) multilayer modified IOL with postoperatively long-term PCO prevention was fabricated via layer by layer (LbL) technique. Quartz crystal microbalance with dissipation monitoring (QCM-D) result shows that HA-Pac/CHI multilayer is modified onto IOL material via LbL technique successfully. The HA-Pac/CHI multilayer coating greatly improves the hydrophilicity of the IOL material surfaces without change the transmittance significantly, whereas the proliferation of LECs is distinctly reduced on the HA-Pac/CHI multilayer-modified surfaces. The drug release in vitro reveals that the multilayer modified IOL material is stable under physiological condition and has good sustained drug release property. All these results demonstrate that HA-Pac/CHI multilayer modified IOL material can effectively inhibit LECs proliferation which provides a novel approach for reducing of PCO incidence in clinical.

Properties of polyplexes formed between a cationic polymer derived from l-arabinitol and nucleic acids

Polyplexes formed between a cationic polymer, PUArab, and both linear and plasmid DNA were studied. The transfection efficiency of PURarab/pDNA was investigated.

Antibacterial Layer-by-Layer Coatings for Medical Implants

The widespread occurrence of nosocomial infections and the emergence of new bacterial strands calls for the development of antibacterial coatings with localized antibacterial action that are capable of facing the challenges posed by increasing bacterial resistance to antibiotics. The Layer-by-Layer (LbL) technique, based on the alternating assembly of oppositely charged polyelectrolytes, can be applied for the non-covalent modification of multiple substrates, including medical implants. Polyelectrolyte multilayers fabricated by the LbL technique have been extensively researched for the development of antibacterial coatings as they can be loaded with antibiotics, antibacterial peptides, nanoparticles with bactericide action, in addition to being capable of restricting adhesion of bacteria to surfaces. In this review, the different approaches that apply LbL for antibacterial coatings, emphasizing those that can be applied for implant modification are presented.

Coarse-Grained Molecular Dynamics (CG-MD) Simulation of the Encapsulation of Dexamethasone in PSS/PDDA Layer-by-Layer Assembled Polyelectrolyte Nanocapsules

Experimental studies have reported the fundamental and applied science aspects of polyelectrolyte (PE) layer-by-layer (LbL) self-assembly. LbL nanocoating is a simple and robust technique that can be used to modify the surface properties of nearly any material. These modifications take place by adsorption of mere nanometers of PE to impart previously absent properties to the nanocoated substrate. Paper manufacturing, drug delivery, and antimicrobial applications have since been developed. LbL self-assembly has become a very lucrative field of research. Computational modeling of LbL nanocoating has received limited attention. PE simulations often require significant computational resources and make computational modeling studies challenging. In this study, atomic-level PE and dexamethasone models are developed and then converted into coarse-grained (CG) models. This modeling study is based on experimental results that were previously reported. The CG models showed the effect of salt concentration and the number of PE layers on the LbL drug nanocapsule. The suitability of the model was evaluated and showed that this model can serve as a predictive tool for an LbL-nanocoated drug delivery system. It is suggested that this model can be used to simulate LbL drug delivery systems before the experimental evaluation of the real systems take place.

Functionalized electrospun nanofiber membranes for water treatment: A review

Electrospun nanofiber membranes (ENMs) have high porosity, high specific surface area and unique interconnected structure. It has huge advantages and potential in the treatment and recycling of wastewater. In addition, ENMs can be easily functionalized by combining multifunctional materials to achieve different water treatment effects. Based on this, this review summarizes the preparation of functionalized ENMs and its detailed application in the field of water treatment. First, the process and influence factors of electrospinning process are introduced. ENMs with high porosity, thin and small fiber diameter have better performance. Secondly, the modification methods of ENMs are analyzed. Pre-electrospinning and post-electrospinning modification technology can prepare specific functionalized ENMs. Subsequently, functionalized ENMs show water treatment capabilities such as separation, adsorption, photocatalysis, and antimicrobial. Subsequently, the application of functionalized ENMs in water treatment capabilities such as separation, adsorption, photocatalysis, and antimicrobial capabilities were listed. Finally, we also made some predictions about the future development direction of ENMs in water treatment, and hope this article can provide some clues and guidance for the research of ENMs in water treatment.

Tumor Microenvironment-Triggered Charge Reversal Polymetformin-Based Nanosystem Co-Delivered Doxorubicin and IL-12 Cytokine Gene for Chemo-Gene Combination Therapy on Metastatic Breast Cancer

Cancer metastasis is the leading cause of high mortality and disease recurrence in breast cancer. In this study, a novel tumor microenvironment charge reversal polymetformin (PMet)-based nanosystem co-delivering doxorubicin (DOX) and plasmid encoding IL-12 gene (pIL-12) was developed for chemo-gene combination therapy on metastatic breast cancer. Cationic PMet was readily self-assembled into micelles for DOX physical encapsulation and pIL-12 complexation, and a hyaluronidase-sensitive thiolated hyaluronic acid (HA-SH) was then collaboratively assembled to the pIL-12/DOX-PMet micelleplexes, abbreviated as HA/pIL-12/DOX-PMet. DOX/pIL-12 loaded in HA/pIL-12/DOX-PMet micelleplexes presented prolonged circulation in blood, efficient accumulation in tumors, and internalization in tumor cells via CD44 receptor-mediated tumor specific-targeting, and DOX/pIL-12 was co-released in endo/lysosomes tumor microenvironment followed by HAase-triggered HA-SH deshielding from HA/pIL-12/DOX-PMet micelleplexes. Moreover, HA/PMet micelleplexes displayed excellent pIL-12 transfection and IL-12 expression in tumors of 4T1 tumor-bearing mice. Importantly, HA/pIL-12/DOX-PMet micelleplexes synergistically enhanced the NK cells and tumor infiltrated cytotoxic T lymphocytes and modulated the polarization from protumor M2 macrophages to activated antitumor M1 macrophages, with concomitant decreasing of the immunosuppressive regulatory T (Treg) cells, accompanied by an increase in the cytokines expression of IL-12, IFN-γ and TNF-α, consequently showing an improved antitumor and antimetastasis activity in 4T1 breast cancer lung metastasis mice model. In conclusion, the tumor microenvironment charge reversal HA/PMet nanosystem holds great promise for DOX/pIL-12 co-delivery and exploitation in chemo-gene combination therapy on metastatic breast cancer.