Dual-functional MOFs-based hybrid microgel advances aqueous lubrication and anti-inflammation

Biomimetic lubricating COFs with donor-acceptor structure for osteoarthritis therapy

Covalent organic framework (COF) possesses special chemical bonds and unique structure and holds great promise in osteoarthritis (OA) therapy. However, non-dispersion in water and single function heavily hinder its further applications. Herein, a donor-acceptor structured biomimetic COF with long-term water dispersing stability, high phototerhmal responsiveness and on-demand drug release for joint lubrication is developed. The designed D-A structure provides effective carrier transport pathways and channels to change near-infrared (NIR) light into heat, and fine control over covalent bonds and reaction conditions endows well-aligned porous structure for drug loading. Biomimetic function with polydopamine provides enriched hydrophilic chemical groups for robust water-dispersity and adhesion, and constructs a hard-soft lubricating system that greatly reduce friction and wear under various conditions for more than 10,800 times without failure. The lubricating system possesses benign cytocompatibility, can be readily taken up into chondrocyte and shows responsively sustained drug release, which achieves anti-inflammatory effects by upregulating the expression levels of Col2α, Aggrecan and downregulating MMP1 and TAC1 mRNA in chondrocytes. We also demonstrate its first experimental example of promoting cell proliferation and migration. Our research suggests an encouraging biomimetic method for combining COF with distinctive structure and multiple functionalities, aiming at an efficient synergistic management of OA.

Microfluidic-engineering Prussian blue hydrogel microspheres for enhanced osteoarthritis antioxidant therapy

Osteoarthritis (OA), a degenerative joint disorder and leading cause of global disabilty, imposes substantial societal and familial burdens. Current antioxidant therapies for OA are hindered by poor targeting and transient efficacy, failing to address the excessive reactive oxygen species (ROS)-driven pathogenesis. Herein, we innovatively integrate Prussian blue (PB) nanozymes with alginate-hyaluronic acid (HA) hydrogel microspheres through microfluidic engineering, creating the injectable AlgHA@PB platform that synergizes dual therapeutic mechanisms: ROS scavenging and oxygen generation via PB nanozymes, and sustained intra-articular retention and mechanical compatibility enabled by the hydrogel microsphere architecture. In vitro studies demonstrated that AlgHA@PB scavenged all of intracellular ROS while continuously releasing oxygen within. In a rat OA model, AlgHA@PB exhibited prolonged joint retention and reduced cartilage degeneration. Critically, the microspheres demonstrated a stable friction coefficient, enabling smooth intra-articular motion without mechanical irritation. This study establishes AlgHA@PB as a multifunctional OA therapeutic platform that integrates antioxidative defense, anti-inflammatory action, and biomechanical compatibility. The microfluidic-engineered design ensures scalable production, aligning with clinical translation requirements.

Dose-effect relationship of copolymer on enhancing aqueous lubrication of a hybrid osteoarthritis drug delivery nanocarrier

Developing stimulus-responsive properties of drug delivery nanocarriers combined with enhanced joint lubrication is an effective synergistic strategy for treating osteoarthritis. Poly(N-isopropylacrylamide) (PNIPAm) is a typical thermo-responsive polymer, which can achieve drug delivery by transition from swollen state to collapsed state. However, undesired transition temperature, limited drug loading capacity, and weakened mechanical properties in joint present obstacles to use as drug delivery nanocarriers. In this work, we demonstrate dose-effect relationship between the PNIPAm-based copolymer and nanoscale metal-organic frameworks on enhancing both aqueous lubrication and drug delivery performance of a hybrid osteoarthritis (OA) nanocarrier. A series of NIPAm and poly(ethylene glycol)methacrylate (PEGMa) copolymer microgels with different feeding content are optimized to grow on the surface of MIL-101(Cr) nanoparticles via one-pot soap-free emulsion copolymerization method. By changing the feeding mass ratio of NIPAm and PEGMa, MIL-101(Cr)@P(NIPAm-g-PEGMax) (x = 0, 1, 2, 3, and 4, named MPNPx) hybrids can ameliorate the lower critical solution temperature to match with OA and enhance the aqueous lubrication performance. Among the as-synthesized hybrids, MPNP3 hybrids manifested the notable enhanced thermo-responsive tribological performance due to the synergistic effect of "hydration lubrication" and "ball-bearing" function of the optimized copolymer microgel layer on the surface of metal-organic frameworks (MOFs). Anti-inflammatory drug loading is enabled by the high surface area and porosity of the MOFs, and the MPNP3 drug delivery nanocarriers achieve thermo-responsive release in vitro. Our work establishes the dose-effect relationship between thermo-responsive NIPAm and hydrophilic PEGMa of the copolymer grown on the surface of MOFs, providing valuable insights for improving the versatility of stimuli-responsive for biomedical application.

Carboxyl-functionalized dual pH/temperature-responsive poly(N-vinylcaprolactam) microgels based on isogenous comonomers for smart window applications

Stimuli-responsive poly(N-vinylcaprolactam) (PVCL)-based microgels, which could response to small external environmental changes, have attracted great interests in the fields of biomedicine and nanotechnology. However, the preparation of such microgels meets severe challenge due to their low incorporation efficiency and thermoresponsivity passivation. To address these issues, we select 3-(tert-butoxycarbonyl)-N-vinylcaprolactam (TBVCL), a carboxyl-functionalized VCL derivative, as a comonomer to develop pH/temperature dual-responsive microgels. TBVCL, with a structure similar to VCL, enhances incorporation efficiency and colloidal stability, while reducing thermoresponsivity passivation. The volume phase transition temperature (VPTT) of the microgels can be adjusted over a broad range (19.0-49.5 °C). Notably, the radial swelling ratios of the microgels can be modulated by pH, achieving a maximum swelling ratio of 3. The distinct changes in dissolution-precipitation behavior under different temperatures or pH conditions make these microgels suitable for applications such as smart windows and sensors. Furthermore, this novel approach for fabricating microgels with pH-tunable phase-transition temperatures demonstrates significant potential for the controlled release of nanoparticles (e.g., drugs, catalysts, and quantum dots) and the development of smart nanocrystal-polymer composite sensors.

A biomimetic lubricating nanosystem for synergistic therapy of osteoarthritis

Failure of articular cartilage lubrication and inflammation are the main causes of osteoarthritis (OA), and integrated treatment realizing joint lubrication and anti-inflammation is becoming the most effective treat model. Inspired by low friction of human synovial fluid and adhesive chemical effect of mussels, our work reports a biomimetic lubricating system that realizes long-time lubrication, photothermal responsiveness and anti-inflammation property. To build the system, a dopamine-mediated strategy is developed to controllably graft hyaluronic acid on the surface of metal organic framework. The design constructs a biomimetic core-shell structure that has good dispersity and stability in water with a high drug loading ratio of 99%. Temperature of the solution rapidly increases to 55 °C under near-infrared light, and the hard-soft lubricating system well adheres to wear surfaces, and greatly reduces frictional coefficient by 75% for more than 7200 times without failure. Cell experiments show that the nanosystem enters cells by endocytosis, and releases medication in a sustained manner. The anti-inflammatory outcomes validate that the nanosystem prevents the progression of OA by down-regulating catabolic proteases and pain-related genes and up-regulating genes that are anabolic in cartilage. The study provides a bioinspired strategy to employ metal organic framework with controlled surface and structure for friction reduction and anti-inflammation, and develops a new concept of OA synergistic therapy model for practical applications.

Application of Injectable Hydrogels as Delivery Systems in Osteoarthritis and Rheumatoid Arthritis

Osteoarthritis and rheumatoid arthritis, though etiologically distinct, are both inflammatory joint diseases that cause progressive joint injury, chronic pain, and loss of function. Therefore, long-term treatment with a focus on relieving symptoms is needed. At present, the primary treatment for arthritis is drug therapy, both oral and intravenous. Although significant progress has been achieved for these treatment methods in alleviating symptoms, certain prominent drawbacks such as the substantial side effects and limited absorption of medications call for an urgent need for improved drug delivery methods. Injected hydrogels can be used as a delivery system to deliver drugs to the joint cavity in a controlled manner and continuously release them, thereby enhancing drug retention in the joint cavity to improve therapeutic effectiveness, which is attributed to the desirable attributes of the delivery system such as low immunogenicity, good biodegradability and biocompatibility. This review summarizes the types of injectable hydrogels and analyzes their applications as delivery systems in arthritis treatment. We also explored how hydrogels counteract inflammation, bone and cartilage degradation, and oxidative stress, while promoting joint cartilage regeneration in the treatment of osteoarthritis (OA) and rheumatoid arthritis (RA). This review also highlights new approaches to developing injectable hydrogels as delivery systems for OA and RA.

Advancements in rheumatoid arthritis therapy: a journey from conventional therapy to precision medicine via nanoparticles targeting immune cells

Rheumatoid arthritis (RA) is a progressive autoimmune disease that mainly affects the inner lining of the synovial joints and leads to chronic inflammation. While RA is not known as lethal, recent research indicates that it may be a silent killer because of its strong association with an increased risk of chronic lung and heart diseases. Patients develop these systemic consequences due to the regular uptake of heavy drugs such as disease-modifying antirheumatic medications (DMARDs), glucocorticoids (GCs), nonsteroidal anti-inflammatory medicines (NSAIDs), etc. Nevertheless, a number of these medications have off-target effects, which might cause adverse toxicity, and have started to become resistant in patients as well. Therefore, alternative and promising therapeutic techniques must be explored and adopted, such as post-translational modification inhibitors (like protein arginine deiminase inhibitors), RNA interference by siRNA, epigenetic drugs, peptide therapy, etc., specifically in macrophages, neutrophils, Treg cells and dendritic cells (DCs). As the target cells are specific, ensuring targeted delivery is also equally important, which can be achieved with the advent of nanotechnology. Furthermore, these nanocarriers have fewer off-site side effects, enable drug combinations, and allow for lower drug dosages. Among the nanoparticles that can be used for targeting, there are both inorganic and organic nanomaterials such as solid-lipid nanoparticles, liposomes, hydrogels, dendrimers, and biomimetics that have been discussed. This review highlights contemporary therapy options targeting macrophages, neutrophils, Treg cells, and DCs and explores the application of diverse nanotechnological techniques to enhance precision RA therapies.

Metal-Organic Framework as a New Type of Magnetothermally-Triggered On-Demand Release Carrier

The development of external stimuli-controlled payload systems has been sought after with increasing interest toward magnetothermally-triggered drug release (MTDR) carriers due to their non-invasive features. However, current MTDR carriers present several limitations, such as poor heating efficiency caused by the aggregation of iron oxide nanoparticles (IONPs) or the presence of antiferromagnetic phases which affect their efficiency. Herein, a novel MTDR carrier is developed using a controlled encapsulation method that fully fixes and confines IONPs of various sizes within the metal-organic frameworks (MOFs). This novel carrier preserves the MOF's morphology, porosity, and IONP segregation, while enhances heating efficiency through the oxidation of antiferromagnetic phases in IONPs during encapsulation. It also features a magnetothermally-responsive nanobrush that is stimulated by an alternating magnetic field to enable on-demand drug release. The novel carrier shows improved heating, which has potential applications as contrast agents and for combined chemo and magnetic hyperthermia therapy. It holds a great promise for magneto-thermally modulated drug dosing at tumor sites, making it an exciting avenue for cancer treatment.

Co-immobilizing laccase-mediator system by in-situ synthesis of MOF in PVA hydrogels for enhanced laccase stability and dye decolorization efficiency

The laccase mediator system (LMS) with a broad substrate range has attracted much attention as an efficient approach for water remediation. However, the practical application of LMS is limited due to their high solubility, poor stability and low reusability. Herein, the bimetallic Cu/ZIFs encapsulated laccase was in-situ grown in poly(vinyl alcohol) (PVA) polymer matrix. The PVA-Lac@Cu/ZIFs hydrogel was formed via one freeze-thawing cycle, and its catalytic stability was significantly improved. The mediator was further co-immobilized on the hydrogel, and this hierarchically co-immobilized ABTS/PVA-Lac@Cu/ZIFs hydrogel could avoid the continuous oxidation reaction between laccase and redox mediators. The co-immobilized LMS biocatalyst was used to degrade malachite green (MG), and the degradation rate was up to 100 % within 4 h. More importantly, the LMS could be recycled synchronously from the dye solutions and reused to degrade MG multiple times. The degradation rate remained above 69.4 % after five cycles. Furthermore, the intermediate products were detected via liquid chromatography-mass spectrometry, and the potential degradation pathways were proposed. This study demonstrated the significant potential of utilizing the MOF nanocrystals and hydrogel as a carrier for co-immobilized LMS, and the effective reuse of both laccase and mediator was promising for laccase application in wastewater treatment.

Application of metal-organic frameworks-based functional composite scaffolds in tissue engineering

With the rapid development of materials science and tissue engineering, a variety of biomaterials have been used to construct tissue engineering scaffolds. Due to the performance limitations of single materials, functional composite biomaterials have attracted great attention as tools to improve the effectiveness of biological scaffolds for tissue repair. In recent years, metal-organic frameworks (MOFs) have shown great promise for application in tissue engineering because of their high specific surface area, high porosity, high biocompatibility, appropriate environmental sensitivities and other advantages. This review introduces methods for the construction of MOFs-based functional composite scaffolds and describes the specific functions and mechanisms of MOFs in repairing damaged tissue. The latest MOFs-based functional composites and their applications in different tissues are discussed. Finally, the challenges and future prospects of using MOFs-based composites in tissue engineering are summarized. The aim of this review is to show the great potential of MOFs-based functional composite materials in the field of tissue engineering and to stimulate further innovation in this promising area.

Development of biomedical hydrogels for rheumatoid arthritis treatment

Rheumatoid Arthritis (RA) is an autoimmune disorder that hinders the normal functioning of bones and joints and reduces the quality of human life. Every year, millions of people are diagnosed with RA worldwide, particularly among elderly individuals and women. Therefore, there is a global need to develop new biomaterials, medicines and therapeutic methods for treating RA. This will improve the Healthcare Access and Quality Index and also relieve administrative and financial burdens on healthcare service providers at a global scale. Hydrogels are soft and cross-linked polymeric materials that can store a chunk of fluids, drugs and biomolecules for hydration and therapeutic applications. Hydrogels are biocompatible and exhibit excellent mechanical properties, such as providing elastic cushions to articulating joints by mimicking the natural synovial fluid. Hence, hydrogels create a natural biological environment within the synovial cavity to reduce autoimmune reactions and friction. Hydrogels also lubricate the articulating joint surfaces to prevent degradation of synovial surfaces of bones and cartilage, thus exhibiting high potential for treating RA. This work reviews the progress in injectable and implantable hydrogels, synthesis methods, types of drugs, advantages and challenges. Additionally, it discusses the role of hydrogels in targeted drug delivery, mechanistic behaviour and tribological performance for RA treatment.

Benchmarking of a microgel-reinforced hydrogel-based aqueous lubricant against commercial saliva substitutes

Xerostomia, the subjective sensation of 'dry mouth' affecting at least 1 in 10 adults, predominantly elders, increases life-threatening infections, adversely impacting nutritional status and quality of life. A patented, microgel-reinforced hydrogel-based aqueous lubricant, prepared using either dairy or plant-based proteins, has been demonstrated to offer substantially enhanced lubricity comparable to real human saliva in in vitro experiments. Herein, we present the benchmarking of in vitro lubrication performance of this aqueous lubricant, both in its dairy and vegan formulation against a range of widely available and employed commercial saliva substitutes, latter classified based on their shear rheology into "liquids", "viscous liquids" and "gels", and also had varying extensional properties. Strikingly, the fabricated dairy-based aqueous lubricant offers up to 41-99% more effective boundary lubrication against liquids and viscous liquids, irrespective of topography of the tested dry mouth-mimicking tribological surfaces. Such high lubricity of the fabricated lubricants might be attributed to their limited real-time desorption (7%) from a dry-mouth mimicking hydrophobic surface unlike the tested commercial products including gels (23-58% desorption). This comprehensive benchmarking study therefore paves the way for employing these microgel-based aqueous lubricant formulations as a novel topical platform for dry mouth therapy.