Polydopamine-based nanomedicines for efficient antiviral and secondary injury protection therapy

Multi-modal microcarriers reprogram mitochondrial metabolism and activate efferocytosis in macrophages for osteoporotic bone repair

Osteoporotic bone repair remains challenging due to the ineffectiveness of traditional bone repair materials in adapting to the complex immune microenvironment of aging bone tissue. Exploiting the key role of macrophages in regulating this immune environment through the rational design of osteoimmunomodulatory biomaterials has emerged as a promising approach. However, current designs inadequately address the complexity of macrophage functions in aging environments, resulting in suboptimal regulatory effects. Hence, we explored multi-modal microcarriers for enhancing macrophage functionality. In this work, we developed a VGX-1027-loaded mesoporous silica nanosphere composite PLLA microcarrier. The dual-carrier system, featuring a micro-nano hybrid design by spatially separating the mesoporous silica nanoparticles and PLLA microspheres, enables sustained intracellular release of VGX-1027, addressing the chronic nature of osteoporotic fractures. Our studies demonstrate this VGX-1027 microcarrier (PMVGX) promotes M2 macrophage polarization by reprogramming mitochondrial metabolism. Simultaneously, it enhances efferocytosis, facilitating the clearance of dead or senescent cells and reducing inflammatory responses, thus reshaping the aging osteoimmunomodulatory. Furthermore, PMVGX induces macrophages to release osteogenic exosomes containing miR-5106 through paracrine signaling, significantly enhancing osteogenic function. In a postmenopausal osteoporosis animal model, PMVGX exhibited remarkable efficacy in repairing osteoporotic bone defects. This proof-of-concept study demonstrates that our multi-modal microcarrier effectively regulates macrophage functions via mitochondrial homeostasis, efferocytosis, and exosome content, offering great potential for osteoporotic bone repair.

Hydrogel-Based Bioactive Synthetic Skin Stimulates Regenerative Gas Signaling and Eliminates Interfacial Pathogens to Promote Burn Wound Healing

Skin burn wounds (SBWs) are common clinical injuries due to excessive exposure to factors including heat, radiation, chemical agents, etc. However, the efficient healing of SBWs is still challenging due to persistent inflammation and high risk of local infection. To meet these challenges, we report a hydrogel-based bioactive synthetic skin (HBSS) from biocompatible components as dressing materials for burn wound treatment, which mediated localized H2S release to stimulate tissue regeneration while preventing bacterial infection and excessive inflammation. Here, the H2S donor (N-(benzoyl mercapto) benzamide) was first coassembled with thioketal (TK)-ligated dopamine dimer to form nanoscale assemblies (DDNs), which were then integrated into Schiff base-cross-linked hyaluronic acid-carboxymethyl chitosan hydrogels. The elevated acidity in burn wounds would trigger hydrogel degradation to release DDNs, which were further activated by ROS-induced cleavage of TK linkers to release H2S gas while attenuating local ROS stress in a self-immolative manner, thus promoting local angiogenesis and tissue regeneration through activating the AMPK and RAS-MAPK-AP1 prohealing pathways, while enabling M1-to-M2 macrophage reprogramming through activating the ERK1/2 and NRF2 signaling. Meanwhile, the chitosan components in the hydrogel network could inhibit bacterial colonization at the wound site to prevent local infection. These merits acted in a cooperative manner to enable accelerated and robust burn wound healing, offering an approach for burn wound treatment in the clinic.

Inflammatory Microenvironment-Responsive Microsphere Vehicles Modulating Gut Microbiota and Intestinal Inflammation for Intestinal Stem Cell Niche Remodeling in Inflammatory Bowel Disease

Intestinal stem cells (ISCs) engage in proliferation to maintain a stable stem cell population and differentiate into functional epithelial subpopulations. This intricate process is upheld by various signals derived from the host and gut microbiota, establishing an ISC niche. However, during inflammatory bowel disease (IBD), this signaling niche undergoes dramatic changes, leading to impaired ISC and hindered restoration of the damaged intestinal epithelial barrier. This study introduces intestinal inflammatory microenvironment-responsive microsphere vehicles designed to remodel the ISC niche, offering an approach to treat IBD. Using an advanced emulsion technique, these microsphere vehicles specifically target colonic inflammation sites, delivering a responsive release of MXene and l-arginine. This delivery system is formulated to modulate intestinal flora and immune responses effectively. l-arginine is converted into nitric oxide to regulate the gut microbiome, while MXene serves as a nanoimmunomodulator to stabilize immune homeostasis. Our findings demonstrate that the anti-inflammatory properties of the microspheres are key to promoting epithelial repair and remodeling of the ISC niche. This study highlights the role of antioxidant microspheres as anti-inflammatory agents that indirectly support ISC function and gut regeneration.

A macrophage-like biomimetic nanoparticle with high-efficiency biofilm disruption and innate immunity activation for implant-related infection therapy

The innate immune system's inactivation and microbial biofilm-induced antibiotic resistance are the main causes of implant-associated infections (IAIs), which frequently result in implant surgical failure. Refractory recolonization is the consequence of standard therapies that are unable to consistently suppress escaping planktonic bacteria from biofilm, thereby enabling IAIs to thrive. Here, we specifically designed a macrophage-like biomimetic nanoparticle (F/R@PM) for a biofilm microenvironment (BME), which was fabricated by coating the cell membrane derived from macrophage onto poly (lactic-co-glycolic acid) (PLGA) namoparticles (NPs) loaded with FOT (NO donor) and R837 (TLR7 agonist). After injecting F/R@PM into mice with implant-associated infections, it was able to selectively target macrophages through macrophage membrane proteins on its surface and effectively release FOT and R837. Then, FOT that spreads outside the cell could react with glutathione (GSH) in the BEM to rapidly produce a large amount of NO inside biofilms to destroy the biofilm and kill bacteria. At the same time, R837 would encourage macrophages to scavenge planktonic bacteria that had escaped biofilm disintegration through improved phagocytosis. Overall, this work shows that NO treatment and immunotherapy together have promising potential for the long-term and efficient control and eradication of IAIs.

Polydopamine-based nano-protectant for prolonged boar semen preservation by eliminating ROS and regulating protein phosphorylation via D2DR-mediated cAMP/PKA signaling pathway

INTRODUCTION

Preservation of porcine semen is essential for artificial insemination and genetic improvement in pig breeding programs. However, the overproduction of reactive oxygen species (ROS) and lower levels of protein phosphorylation emerge as two challenges during semen preservation. Inspired by the innate ligand-receptor binding biofunction of dopamine, herein, a dual-task nano-protectant that combines ROS-scavenging and protein phosphorylation-regulating properties via incorporating the natural antioxidant epigallocatechin gallate (EGCG) into polydopamine nanoparticles (EGCG@PDA NPs) was proposed to enhance the quality of pig semen during storage at 4 ℃. The results suggested that EGCG@PDA NPs significantly maintained sperm motility, acrosome integrity and mitochondrial membrane potential, extending semen storage time from 3 days to 10 days. Furthermore, EGCG@PDA NPs effectively scavenged excess ROS and inhibited ROS-mediated sperm apoptosis through the extracellular regulated protein kinases (ERK) signaling pathway. Intriguingly, EGCG@PDA NPs could degrade into ultrasmall particles (< 10 nm) in the semen or H2O2 systems. These particles could target and activate the dopamine D2 receptor (D2DR) on membrane surface of sperm midpiece, thereby enhancing protein phosphorylation via the downstream cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway, ultimately improving sperm motility parameters. This study presents a novel nano-strategy to boost the quality of pig semen, offering significant implications for the pig industry.

Macrophage Membrane-Encapsulated Carbon Dots for Precise Targeting Diagnosis and Treatment of Bacterial Infections

How to accurately diagnose and treat bacterial infections in vivo remains a huge challenge. Therefore, we have developed a targeted delivery nanosystem by coextruding the pretreated macrophage membrane of S. aureus with carbon dots (M@CD). The M@CD nanosystem demonstrates potent antibacterial effects both in vivo and in vitro through the generation of reactive oxygen species (ROS). Furthermore, M@CD exhibits enhanced targeting ability and stable fluorescence properties, addressing issues such as poor targeting efficiency and high immunogenicity in vivo. This innovative approach enables infection site specific aggregation and elimination of bacterial infections, thereby providing a promising strategy for the integrated diagnosis, treatment, and monitoring of bacterial infections.

A Multi-functional Hybrid System Comprised of Polydopamine Nanobottles and Biological Effectors for Cartilage Repair

Biological effectors play critical roles in augmenting the repair of cartilage injuries, but it remains a challenge to control their release in a programmable, stepwise fashion. Herein, a hybrid system consisting of polydopamine (PDA) nanobottles embedded in a hydrogel matrix to manage the release of biological effectors for use in cartilage repair is reported. Specifically, a homing effector is load in the hydrogel matrix, together with the encapsulation of a cartilage effector in PDA nanobottles filled with phase-change material. In action, the homing effector is quickly released from the hydrogel in the initial step to recruit stem cells from the surroundings. Owing to the antioxidation effect of PDA, the recruited cells are shielded from reactive oxygen species. The cartilage effector is then slowly released from the nanobottles to promote chondrogenic differentiation, facilitating cartilage repair. Altogether, this strategy encompassing recruitment, protection, and differentiation of stem cells offers a viable route to tissue repair or regeneration through stem cell therapy.

A biocompatible polydopamine platform for targeted delivery of nicotinamide mononucleotide and boosting NAD+ levels in the brain

Nicotinamide mononucleotide (NMN), a precursor of the coenzyme nicotinamide adenine dinucleotide (NAD+), has gained wide attention as an anti-aging agent, which plays a significant role in intracellular redox reactions. However, its effectiveness is limited by easy metabolism in the liver and subsequent excretion as nicotinamide, resulting in low bioavailability, particularly in the brain. Additionally, the blood-brain barrier (BBB) further hinders NMN supply to the brain, compromising its potential anti-aging effects. Herein, we developed a biocompatible polydopamine (PDA) platform to deliver NMN for boosting NAD+ levels in the brain for the first time. The lactoferrin (Lf) ligand was covalently attached to the PDA spheres to improve BBB transport efficiency. The resultant PDA-based system, referred to as PDA-Lf-NMN, not only exhibited superior BBB penetration ability but also improved the utilization rate of brain NMN in elevating NAD+ levels compared to NMN alone for both young (3 months) and old (21 months) mice. Moreover, after the old mice were treated with low-dose PDA-Lf-NMN (8 mg kg-1 day-1), they exhibited improved spatial cognition. Importantly, these nanomedicines did not induce any cellular necrosis or apoptosis. It provides a promising avenue for delivering NMN specifically to the brain, boosting NAD+ levels for promoting longevity and treating brain aging-related diseases.

Pyroptotic-Spatiotemporally Selective Delivery of siRNA against Pyroptosis and Autoimmune Diseases

Small-interfering RNAs (siRNAs) offer promising prospects for treating pyroptosis-related autoimmune diseases. However, poor stability and off-target effects during in vivo transportation hinder their practical clinical applications. Precision delivery and adaptive release of siRNAs into inflamed tissues and immune cells could unleash their full therapeutic potential. This study establishes a pyroptotic-spatiotemporally selective siRNA delivery system (PMRC@siGSDME) that selectively targets inflammatory tissues, responds to pyroptosis, and exhibits remarkable therapeutic efficacy against various autoimmune diseases. Novel hybrid nanovesicles (NVs) are designed as a combination of pyroptotic macrophage membranes (PMs) and R8-cardiolipin-containing nanovesicles (RC-NVs). Evidence provides that PM-derived proteins involved in cell-cell interactions and membrane trafficking may contribute to the specificity of NVs to inflammatory tissue. In addition, cardiolipin anchored in the hybrid NVs increases its affinity for activated gasdermin E (GSDME) and achieves pyroptosis-adaptive release of siGSDME for the spatiotemporally selective suppression of immune responses. More importantly, PMRC@siGSDME displays significant anti-inflammatory and therapeutic effects in multiple mouse autoimmune disease models, including arthritis and inflammatory bowel disease (IBD). Collectively, an innovative siRNA delivery strategy precisely tailored for pyroptotic cells has been developed, paving the way for new treatments for autoimmune inflammatory diseases with minimal side effects and wide clinical applicability.

Fullerol-reinforced antioxidantive 3D-printed bredigite scaffold for accelerating bone healing

Reactive oxygen species play a vital role in tissue repair, and nonequilibrium of redox homeostasis around bone defect can compromise osteogenesis. However, insufficient antioxidant capacity and weak osteogenic performance remain major obstacles for bone scaffold materials. Herein, integrating the mussel-inspired polydopamine (PDA) coating and 3D printing technologies, we utilized the merits of both osteogenic bredigite and antioxidative fullerol to construct 3D-printed porous, biodegradable acid-buffering, reactive oxygen species (ROS) -scavenging and robust osteogenic bio-scaffold (denoted "FPBS") for in situ bone defect restoration under oxidative stress microenvironment. Initially, fullerol nanoparticles were attached to the surface of the bredigite scaffold via covalently inter-crosslinking with PDA. Upon injury, extracellular ROS capturing triggered the oxidative degradation of PDA, releasing fullerol nanoparticles to enter into cells for further intracellular ROS scavenging. In vitro, FPBS had good biocompatibility and excellent antioxidative capability. Furthermore, FPBS promoted the osteogenesis of stem cells with significant elevation of osteogenic markers. Finally, in vivo implantation of FPBS remarkably enhanced new bone formation in a rat critical calvarial defect model. Overall, with amelioration of the ROS microenvironment of injured tissue and enhancement of osteogenic differentiation of stem cells simultaneously, FPBS may hold great potential towards bone defect repair.

Bioactive Nanofiber-Hydrogel Composite Regulates Regenerative Microenvironment for Skeletal Muscle Regeneration after Volumetric Muscle Loss

Volumetric muscle loss (VML) is a severe form of muscle trauma that exceeds the regenerative capacity of skeletal muscle tissue, leading to substantial functional impairment. The abnormal immune response and excessive reactive oxygen species (ROS) accumulation hinder muscle regeneration following VML. Here, an interfacial cross-linked hydrogel-poly(ε-caprolactone) nanofiber composite, that incorporates both biophysical and biochemical cues to modulate the immune and ROS microenvironment for enhanced VML repair, is engineered. The interfacial cross-linking is achieved through a Michael addition between catechol and thiol groups. The resultant composite exhibits enhanced mechanical strength without sacrificing porosity. Moreover, it mitigates oxidative stress and promotes macrophage polarization toward a pro-regenerative phenotype, both in vitro and in a mouse VML model. 4 weeks post-implantation, mice implanted with the composite show improved grip strength and walking performance, along with increased muscle fiber diameter, enhanced angiogenesis, and more nerve innervation compared to control mice. Collectively, these results suggest that the interfacial cross-linked nanofiber-hydrogel composite could serve as a cell-free and drug-free strategy for augmenting muscle regeneration by modulating the oxidative stress and immune microenvironment at the VML site.

Immune-like sandwich multiple hotspots SERS biosensor for ultrasensitive detection of NDKA biomarker in serum

Developing the rapid, specific, and sensitive tumor marker NDKA biosensor has become an urgent need in the field of early diagnosis of colorectal cancer (CRC). Surface-enhanced Raman spectroscopy (SERS) with the advantages of high sensitivity, high resolution as well as providing sample fingerprint, enables rapid and sensitive detection of tumor markers. However, many SERS biosensors rely on boosting the quantity of Raman reporter molecules on individual nanoparticle surfaces, which can result in nanoparticle agglomeration, diminishing the stability and sensitivity of NDKA detection. Here, we proposed an immune-like sandwich multiple hotspots SERS biosensor for highly sensitive and stable analysis of NDKA in serum based on molecularly imprinted polymers and NDKA antibody. The SERS biosensor employs an array of gold nanoparticles, which are coated with a biocompatible polydopamine molecularly imprinted polymer as a substrate to specifically capture NDKA. Then the biosensor detects NDKA through Raman signals as a result of the specific binding of NDKA to the SERS nanotag affixed to the capture substrate along with the formation of multiple hotspots. This SERS biosensor not only avoids the aggregation of nanoparticles but also presents a solution to the obstacles encountered in immune strategies for certain proteins lacking multiple antibody or aptamer binding sites. Furthermore, the practical application of the SERS biosensor is validated by the detection of NDKA in serum with the lower limit of detection (LOD) of 0.25 pg/mL, meanwhile can detect NDKA of 10 ng/mL in mixed proteins solution, illustrating high sensitivity and specificity. This immune-like sandwich multiple hotspots biosensor makes it quite useful for the early detection of CRC and also provides new ideas for cancer biomarker sensing strategy in the future.

Dual-crosslinking immunostimulatory hydrogel synchronously suppresses pancreatic fistula and pancreatic cancer relapse post-resection

In pancreatic cancer (PC), surgical resection remains the sole curative option, albeit patients undergoing resection are susceptible to postoperative pancreatic fistula (PF) formation and tumor recurrence. An unmet need exists for a unified strategy capable of concomitantly averting PF and tumor relapse to mitigate morbidity in PC patients after surgery. Herein, an original dual crosslinked biological sealant hydrogel (methacrylate-hyaluronic acid-dopamine (MA-HA-DA) and sulfhydryl-hyaluronic acid-dopamine (SH-HA-DA)) was engineered as a drug depot and loaded with polydopamine-cloaked cytokine interleukin-15 and platelets conjugated with anti-TIGIT. In vitro analyses validated favorable tissue adhesion, cytocompatibility, and stability of the hydrogels. In a PF rodent model, the hydrogel effectively adhered to the pancreatic stump, sealing the severed pancreatic end and impeding post-operative elevations in amylase and lipase. In PC murine models, hydrogels potently stimulated CD8+ T and NK cells to deter residual tumor re-growth and distant metastasis. This innovative hydrogel strategy establishes a new framework for concomitant prevention of PF and PC recurrence.

Bio-Responsive Sliver Peroxide-Nanocarrier Serves as Broad-Spectrum Metallo-β-lactamase Inhibitor for Combating Severe Pneumonia

Metallo-β-lactamases (MBLs) represent a prevalent resistance mechanism in Gram-negative bacteria, rendering last-line carbapenem-related antibiotics ineffective. Here, a bioresponsive sliver peroxide (Ag2 O2 )-based nanovesicle, named Ag2 O2 @BP-MT@MM, is developed as a broad-spectrum MBL inhibitor for combating MBL-producing bacterial pneumonia. Ag2 O2 nanoparticle is first orderly modified with bovine serum albumin and polydopamine to co-load meropenem (MER) and [5-(p-fluorophenyl)-2-ureido]-thiophene-3-carboxamide (TPCA-1) and then encapsulated with macrophage membrane (MM) aimed to target inflammatory lung tissue specifically. The resultant Ag2 O2 @BP-MT@MM effectively abrogates MBL activity by displacing the Zn2+ cofactor in MBLs with Ag+ and displays potent bactericidal and anti-inflammatory properties, specific targeting abilities, and great bioresponsive characteristics. After intravenous injection, the nanoparticles accumulate prominently at infection sites through MM-mediated targeting . Ag+ released from Ag2 O2 decomposition at the infection sites effectively inhibits MBL activity and overcomes the resistance of MBL-producing bacteria to MER, resulting in synergistic elimination of bacteria in conjunction with MER. In two murine infection models of NDM-1+ Klebsiella pneumoniae-induced severe pneumonia and NDM-1+ Escherichia coli-induced sepsis-related bacterial pneumonia, the nanoparticles significantly reduce bacterial loading, pro-inflammatory cytokine levels locally and systemically, and the recruitment and activation of neutrophils and macrophages. This innovative approach presents a promising new strategy for combating infections caused by MBL-producing carbapenem-resistant bacteria.

Macrophage-related therapeutic strategies: Regulation of phenotypic switching and construction of drug delivery systems

Macrophages, as highly phenotypic plastic immune cells, play diverse roles in different pathological conditions. Changing and controlling the phenotypes of macrophages is considered a novel potential therapeutic intervention. Meanwhile, specific transmembrane proteins anchoring on the surface of the macrophage membrane are relatively conserved, supporting its functional properties, such as inflammatory chemotaxis and tumor targeting. Thus, a series of drug delivery systems related to specific macrophage membrane proteins are commonly used to treat chronic inflammatory diseases. This review summarizes macrophages-based strategies for chronic diseases, discusses the regulation of macrophage phenotypes and their polarization processes, and presents how to design and apply the site-specific targeted drug delivery systems in vivo based on the macrophages and their derived membrane receptors. It aims to provide a better understanding of macrophages in immunoregulation and proposes macrophages-based targeted therapeutic approaches for chronic diseases.

Cell-nano interactions of polydopamine nanoparticles

Polydopamine (PDA) nanoparticles (NPs) have diverse nanomedicine applications owing to their biocompatibility and abundant entry to cells. Yet, our knowledge in their interactions with cells was infrequently studied until recent years. This review presents the latest insights into the cell-nano interactions of PDA NPs, including their 'self-targeting' to dopamine receptors for cellular entry without the aid of ligands, in vitro 'self-therapeutic' cellular responses (antiferroptosis, macrophage polarization, and modulation of mitochondrial bioenergetics) in the absence of drugs, and in vivo cellular localization and pharmacological properties upon various routes of administration. This review concludes with our perspectives on the therapeutic promise of PDA NPs and the need for studies on PDA biochemistry, biodegradability, and protein adsorption.