Melanin Nanoparticles Research Articles

Capsaicin-Loaded Melanin Nanoparticles for Long-Lasting Nociceptive-Selective Nerve Blockade.

Clinically used amino-ester and amino-amide local anesthetics, such as bupivacaine and lidocaine, face two primary challenges: inadequate duration of action and nonselective action on both sensory and motor neurons, resulting in motor function loss alongside pain relief. In this work, we developed capsaicin-loaded melanin nanoparticles (Cap-MNPs) to address these two challenges. Capsaicin selectively acts on sensory neurons without affecting motor neurons, thereby achieving nociceptive-selective nerve blockade. Melanin is known for its exceptional biocompatibility, biodegradability, and abundance in pigmented human tissue. Melanin's inherent chemical structure and hydrophobic nature enable the encapsulation and sustained release of amino-ester and amino-amide local anesthetics with aromatic rings through π-π interactions and hydrophobic interactions. The drug loading efficiency of Cap-MNPs was 82.99 ± 1.55%, the drug loading capacity was 67.47 ± 4.24%, and capsaicin was continuously released for more than 360 h. In rats, a single injection of Cap-MNPs containing 8.04 mg of capsaicin produced a sciatic sensory nerve block lasting for 6 h without causing any local toxicity and capsaicin-related systemic toxicity. Cap-MNPs show promise as clinically useful therapeutics for pain management.

Melanin Hydrogel Inverse Opal Microneedle Patches for Wound Healing.

Bacterial infected wounds bring an economic burden to the worldwide medical care field. A variety of bioactives-integrated hydrogel patches are developed in response to this challenge. Here, the melanin hydrogel inverse opal microneedle patches (MNs) with antioxidant and visual color sensing abilities for the management of bacterial infected wounds are proposed. The MNs are fabricated by applying melanin-loaded polyethylene glycol diacrylate (PEGDA) as the inverse opal hydrogel and using bacitracin-carried gelatin to fill those nanopores of hydrogel scaffold. Benefitting from the antioxidant capacity of melanin nanoparticles and the local antimicrobial ability of bacitracin, the resulting MNs possess the integrated functions of reactive oxygen species scavenging and antibacterial. Besides, the inverse opal structure endows the MNs with vivid structure color and detectable reflected wavelength, which can gradually shift with the release of the drug, thus allowing MNs to assess the drug delivery. Based on these characteristics, MNs perform excellent in in vitro drug delivery and monitoring, as well as the promotion of bacterial infected wound recovery in vivo, indicating the potential of MNs in the future wound management field.

Melanin-intercalated layered double hydroxide LDH/MNP as a stable photothermal agent

Melanin nanoparticles (MNPs) are a type of electronegative compound that can be used as photothermal agent for cancer treatment. Nevertheless, the agglomeration of MNP, which is one of the limitations in practice, contributes to the instability of MNP. Pristine layered double hydroxide (LDH), as a kind of positive inorganic material when there exist no other cargo between its layers, can accommodate electronegative molecules between its layers to endow them with stable properties. Hence, in this study, electronegative MNP was intercalated into LDH lamellas via ion-exchange method to obtain the stable original photothermal agent LDH/MNP, solving the tough problem of MNP’s agglomeration. The surface morphology, X-ray diffraction and fourier transform infrared spectra affirmed the successful intercalation of MNP between LDH lamellas. The Z-average particle sizes of LDH/MNP on day 0, 7 and 14 were measured as 221.8 nm, 227.6 nm and 230.5 nm without obvious fluctuation, while the particle sizes of MNP went through dramatic enlargement from 105.8 nm (day 0) to 856.1 nm (day 7), indicating the better stability of LDH/MNP than MNP. The typical polymer dispersity index (PDI) values on day 0, 7 and 14 verified the better stability of LDH/MNP, too. Photothermal properties of LDH/MNP were assessed and the results ensured the representative photothermal properties of LDH/MNP. The fine cytocompatibility of LDH/MNP was verified via cytotoxicity test. Results confirmed that the agglomeration of MNP disappeared after its intercalation into LDH and LDH/MNP possessed fine stability as well as typical photothermal property. The intercalation of MNP into LDH gave the photothermal agent MNP a promising way for its better stability and long-term availability in photothermal treatment.

Versatile conductive hydrogel orchestrating neuro–immune microenvironment for rapid diabetic wound healing through peripheral nerve regeneration

Diabetic wound (DW), notorious for prolonged healing processes due to the unregulated immune response, neuropathy, and persistent infection, poses a significant challenge to clinical management. Current strategies for treating DW primarily focus on alleviating the inflammatory milieu or promoting angiogenesis, while limited attention has been given to modulating the neuro-immune microenvironment. Thus, we present an electrically conductive hydrogel dressing and identify its neurogenesis influence in a nerve injury animal model initially by encouraging the proliferation and migration of Schwann cells. Further, endowed with the synergizing effect of near-infrared responsive release of curcumin and nature-inspired artificial heterogeneous melanin nanoparticles, it can harmonize the immune microenvironment by restoring the macrophage phenotype and scavenging excessive reactive oxygen species. This in-situ formed hydrogel also exhibits mild photothermal therapy antibacterial efficacy. In the infected DW model, this hydrogel effectively supports nerve regeneration and mitigates the immune microenvironment, thereby expediting the healing progress. The versatile hydrogel exhibits significant therapeutic potential for application in DW healing through fine-tuning the neuro-immune microenvironment.

Different Biocompatibility and Radioprotective Activity of Squid Melanin Nanoparticles on Human Stromal Cells.

Squid ink melanin nanoparticles (NPs) have recently been demonstrated to have a number of bioactivities; however, their biocompatibility has been poorly investigated. In this study, we aimed to evaluate the effects of this NP on stromal cells, including human fibroblasts (hFBs), human umbilical vein endothelial cells (hUVECs), and human umbilical cord-derived mesenchymal stem cells (UCMSCs), and on the development of zebrafish embryos under normal X-ray irradiation conditions. The NPs showed high biocompatibility with low cytotoxicity, no cell senescence induction, and no effect on cell migration in hFBs or cell differentiation in UCMSCs. Nonetheless, this compound prevented cell movement in UCMSCs and significantly suppressed tube formation in hUVECs at a dose of 25 μg/mL. The NPs successfully penetrated the hUVECs but not the other two stromal cell types. The expression levels of functional genes involved in angiogenesis, apoptosis, antioxidant activity, and radiation sensitivity were altered in NPs subjected to hUVECs but were not affected in hFBs and UCMSCs. Melanin NPs significantly rescued cell viability and gene expression in irradiated hFBs and UCMSCs but not in hUVECs. In vivo treatments of zebrafish embryos showed that melanin NPs were nontoxic whether alone or under X-ray irradiation. These findings suggested that nanosized squid ink melanin had biocompatibility with selective stromal cells and was safe for early development.

Cuttlefish ink-derived melanin nanoparticle-embedded tremella fuciformis polysaccharide hydrogels for the treatment of MRSA-infected diabetic wounds

Diabetic wounds arise great attention as they are difficult to heal and easily suffer from serious bacterial infection. However, the overuse of antibiotics increases the resistance of bacteria and makes common drugs ineffective. Here, we developed a photothermal hydrogel (TFP/NP) composed of tremella fuciformis polysaccharides (TFPs) and cuttlefish ink-derived melanin nanoparticles (NPs). The NPs can produce reliable photothermal effects under near-infrared laser (NIR) irradiation and help to remove the bacteria in the wounds, while TFPs were able to form hydrogel frameworks which possessed anti-inflammatory effects and could be applied to promote wound healing. The TFP/NP hydrogels produced stable thermal effects under NIR irradiation and could continuously kill bacteria. The experiment on a full-layer skin wound sMRSA activity and could improve the healing efficiency. The wounds of the mice could be repaired within 14 days after reasonable treatment. In addition, the hydrogels play significant roles in promoting collagen deposition, anti-inflammation, angiogenesis, and cell proliferation during the therapeutic process. This research provides a simple and effective method for the therapy of bacterial infection wounds through the synergistic effect of TFPs and NPs.

Characterization and in vitro evaluation of melanin nanoparticles as an oral drug delivery system: Studies using Caco-2 cell model and molecular dynamics simulations

Interest has been shown in the use of melanin nanoparticles (MNPs) for drug delivery applications. This study investigates the potential use of MNPs as an oral drug delivery system. The toxicity and cellular uptake of MNPs via intestinal barrier were evaluated using the Caco-2 cell model. Doxorubicin (DOX) was selected as a representative low bioavailability drug. The DOX-release profile of drug-loaded MNPs and molecular dynamic (MD) simulation were investigated at different pH. Our results demonstrated that MNPs synthesized from dopamine HCl are suitable as nanocarriers, presenting as monodisperse particles at mean size <300 nm. MNPs at size 89, 156, 268 nm at 3.13–50 μg/mL showed a high biocompatibiltity with Caco-2 cells, since no significant changes in %cell viability, reactive oxygen species, mitochondria membrane potential, and inflammatory cytokine were observed. The TEM results exhibited cellular internalization of MNPs into Caco-2 cells. The loading capacity (LC) and entrapment efficiency (EE) of DOX-loaded MNPs were 13.3 ± 2.7 % and 30.0 ± 3.6 %, respectively. DOX-loaded MNPs possessed a pH-dependent drug release profile. At pH 1.2, the amount of liberated DOX was 1.6- and 3.8-fold increase in comparison to pH 5 and 7.4, respectively. MD simulation clearly demonstrated that the binding affinity between polydopamines of MNPs and DOX molecules was weaker at the lower pH. These results thus support the potential use of MNPs as an oral drug delivery system particularly for drugs used in cancer treatment.

Anti-IgG Doped Melanin Nanoparticles Functionalized Quartz Tuning Fork Immunosensors for Immunoglobulin G Detection: In Vitro and In Silico Study.

The quartz tuning fork (QTF) is a promising instrument for biosensor applications due to its advanced properties such as high sensitivity to physical quantities, cost-effectiveness, frequency stability, and high-quality factor. Nevertheless, the fork's small size and difficulty in modifying the prongs' surfaces limit its wide use in experimental research. Our study presents the development of a QTF immunosensor composed of three active layers: biocompatible natural melanin nanoparticles (MNPs), glutaraldehyde (GLU), and anti-IgG layers, for the detection of immunoglobulin G (IgG). Frequency shifts of QTFs after MNP functionalization, GLU activation, and anti-IgG immobilization were measured with an Asensis QTF F-master device. Using QTF immunosensors that had been modified under optimum conditions, the performance of QTF immunosensors for IgG detection was evaluated. Accordingly, a finite element method (FEM)-based model was produced using the COMSOL Multiphysics software program (COMSOL License No. 2102058) to simulate the effect of deposited layers on the QTF resonance frequency. The experimental results, which demonstrated shifts in frequency with each layer during QTF surface functionalization, corroborated the simulation model predictions. A modelling error of 0.05% was observed for the MNP-functionalized QTF biosensor compared to experimental findings. This study validated a simulation model that demonstrates the advantages of a simulation-based approach to optimize QTF biosensors, thereby reducing the need for extensive laboratory work.

Melanin Nanoparticle-Modified Probiotics for Targeted Synergistic Therapy of Ulcerative Colitis.

Ulcerative colitis (UC) is a recurrent chronic mucosal inflammation disease whose most significant pathological characteristics are intestinal inflammation and damaged mucosal barrier induced by reactive oxygen/nitrogen species, abnormal immune microenvironment, and intestinal microecological imbalance. Oral probiotics are a living therapy for intestinal diseases, but their clinical application is hindered by poor bacterial biological activity and insufficient intestinal retention. Here, we developed a targeted oral formulation, functionalized probiotic Lf@MPB, with Lactobacillus fermentum (Lf) as the core and modified melanin nanoparticles (MNPs) on its surface through a click reaction of tricarboxyphenylboronic acid for synergistic therapy of UC. In vitro experiments showed that Lf@MPB not only possessed strong free radical scavenging ability, reduced cellular mitochondrial polarization, and inhibited apoptosis but also significantly enhanced the viability of Lf probiotics in simulated gastrointestinal fluid. Fluorescence imaging in vivo revealed the high accumulation of Lf@MPB at the site of intestinal inflammation in dextran sulfate sodium-induced UC mice. Moreover, in vivo results demonstrated that Lf@MPB effectively alleviated oxidative stress and inflammatory response and restored the intestinal barrier. In addition, 16S rRNA gene sequencing verified that Lf@MPB could increase the abundance and diversity of intestinal microbial communities and optimize microbial composition to inhibit the progression of UC. This work combines effective antioxidant and anti-inflammatory strategies with the oral administration of functionalized probiotics to provide a promising alternative for UC treatment.

Non-pigmented laser hair removal mediated via sepia melanin nanoparticles: in vivo study on albino mice

Objectives Melanin is considered the main chromophore for laser hair removal. Due to a lack of laser-absorbing chromophores, removing non-pigmented hair with laser is quite problematic with unsatisfactory outcomes. This problem could be solved by delivering more melanin to the area around the hair follicle and enhancing that area as a target for light absorption. The insolubility of Sepia melanin as an exogenous dye, in most solvents, limits its bioavailability and thus its clinical use. Methods In our study, to overcome the solubility problems and increase the bioavailability of melanin for biomedical and cosmetic applications, natural sepia melanin was loaded in different nano-delivery systems (spanlastics and transfersomes) to be delivered to the hair follicles. The different formulations of melanin were prepared and characterized. In vivo skin deposition and histopathological studies were conducted on albino mice. Results Transmission electron microscopy (TEM) showed the spherical shape of the prepared vesicles with an average particle size of 252 and 262 nm and zeta potential of −22.5 and −35 mV for melanin spanlastics and melanin transfersomes, respectively. Histopathological examination of hair follicles and pilosebaceous glands for the irradiated and non-irradiated albino mice skin was studied post the application of the prepared formulations topically and subcutaneously. Qualitative statistical analysis was conducted and melanin transfersomes and melanin spanlastics showed significant damage to pilosebaceous glands and hair follicles with a p-value of 0.031 and 0.009 respectively. Conclusion Melanin nanovesicles as transfersomes and spanlastics could be considered a promising approach for the removal of non-pigmented hair.

Melanin-based duplex Cas9 ribonucleoprotein nanomedicine for synergistic phototherapy and immunotherapy

Immune checkpoint blockade (ICB) has shown significant progress in treating triple negative breast cancer (TNBC). However, the standalone effectiveness of ICB is modest, offering patients only slight benefits. In this report, we utilize a hypoxia-responsive duplex genome editing strategy to target tumor cell programmed cell death ligand 1 (PD-L1) and protein tyrosine phosphatase non-receptor type 2 (PTPN2), which is synergized with photothermal therapy (PTT) to amplify the therapeutic effect of TNBC. In our approach, the melanin nanoparticles (MNP) serve as the delivery platform for transporting the CRISPR-CasPTPN2/PD-L1 (Cas-TD) system, which is cross-linked by a hypoxic-sensitive Azo linker and then further modified with tumor homing phenylboronic acid (PBA), resulting in a stimuli-responsive multifunctionality nanotheranostic platform (MPA@Cas-TD@PP). Aided by the guidance of PBA, nanoparticles selectively accumulate at tumor and then disintegrate with enhanced intracellular penetration. Importantly, PTT initiates the immunogenic cell death (ICD), turning the “cold” tumor into a “hot” one, laying the foundation for subsequent ICB. Inhibiting PTPN2 and PD-L1 can synergistically sensitize tumors to immunotherapy, which exhibit magnified immunotherapy effects by increasing activated cytotoxic CD8+ T cells and enhancing interferon-γ (IFN-γ)-mediated effects. In summary, this multifunctional nanotherapeutic platform provides a promising treatment approach for synergistic phototherapy and immunotherapy in TNBC.

Melanin for Photoprotection and Hair Coloration in the Emerging Era of Nanocosmetics.

Nanotechnology is revolutionizing fields of high social and economic impact. such as human health preservation, energy conversion and storage, environmental decontamination, and art restoration. However, the possible global-scale application of nanomaterials is raising increasing concerns, mostly related to the possible toxicity of materials at the nanoscale. The possibility of using nanomaterials in cosmetics, and hence in products aimed to be applied directly to the human body, even just externally, is strongly debated. Preoccupation arises especially from the consideration that nanomaterials are mostly of synthetic origin, and hence are often seen as "artificial" and their effects as unpredictable. Melanin, in this framework, is a unique material since in nature it plays important roles that specific cosmetics are aimed to cover, such as photoprotection and hair and skin coloration. Moreover, melanin is mostly present in nature in the form of nanoparticles, as is clearly observable in the ink of some animals, like cuttlefish. Moreover, artificial melanin nanoparticles share the same high biocompatibility of the natural ones and the same unique chemical and photochemical properties. Melanin is hence a natural nanocosmetic agent, but its actual application in cosmetics is still under development, also because of regulatory issues. Here, we critically discuss the most recent examples of the application of natural and biomimetic melanin to cosmetics and highlight the requirements and future steps that would improve melanin-based cosmetics in the view of future applications in the everyday market.

Construction of janus mesenchymal stem cell-hitchhiked melanin nanoparticles to modulate the Th17/Treg balance for rheumatoid arthritis therapy

Rheumatoid arthritis (RA) is a common chronic inflammatory disease capable of causing the disability. Although various antioxidant strategies have been attempted for prevention and treatment of RA through scavenging the free radicals, the therapeutic effect is limited. Recently, it is reported that the unremitting course of RA intensely correlates with the persistence of immunologic memory, in which the imbalance of T helper 17 (Th17) cells/regulatory T (Treg) cells plays an important role. Herein, we constructed Janus mesenchymal stem cell (MSC)-hitchhiked melanin nanoparticles (MSCFM) for RA therapy, where one half of MSC kept intact for chemotactically migrating towards the RA inflammatory sites and efficiently restoring the Th17/Treg balance based on the property of MSCs, while the other half hitchhiked the iron-doped melanin (FM) nanoparticles (NPs) and release them to scavenge free radicals for maintaining the durability of Th17/Treg balance. In vitro studies indicated MSCFM could migrate towards CXCL12 inflammatory cytokine, scavenge reactive oxygen and nitrogen species, inhibit Th17 cell proliferation and induce Treg cell production. Further in vivo studies corroborated that intravenously injected MSCFM could target the RA site of collagen-induced arthritis mouse model and alleviate the pathological progression of RA. MSCFM holds great potential as an anti-inflammatory agent for RA management.

Melanin nanoparticles scavenging reactive oxygen and nitrogen radicals for rheumatoid arthritis treatment

Rheumatoid arthritis (RA) is a complex and chronic disease that often causes long-term pain and joint swelling in patients, and even causes joint deformity and dysfunction. The pathogenesis of this disease involves abnormal activity of the immune system, causing immune cells to attack the bodys joint tissues, which triggers an inflammatory response. During these inflammatory processes, the accumulation of reactive oxygen and nitrogen species (RONS) is considered to be one of the key factors that aggravate inflammation and damage joint tissues. To address this problem, we designed a method that takes advantage of the targeting properties of melanin nanoparticles. These nanoparticles have excellent biocompatibility, can remain stable in the body, and can be accurately targeted to the site of inflammation. In addition, these nanoparticles also have strong free radical scavenging ability, which can effectively neutralize excessive RONS, reduce the inflammatory response and weaken joint tissue damage. The promise of this treatment strategy is encouraging and offers new hope for patients with RA. By reducing inflammation, protecting joint tissue, and possibly even reversing the disease process to some extent, this melanin nanoparticle holds great promise.

Natural melanin nanoparticles (MNPs) extracted from Sepia officinalis: A cost-effective, chemo-photothermal, synergistic nanoplatform for osteosarcoma treatment

Osteosarcoma conventional chemotherapeutics are known for their side effects, limited options, and induction of drug resistance. This creates the need to develop new therapeutics capable of effectively destroying cancer cells with low toxicity, improving patient survival rate and their life quality. This work reports a novel drug delivery nanoplataform made of Natural Melanin Nanoparticles (MNPs), obtained from Sepia officinalis ink, with 99% incorporation efficiency of doxorubicin (Dox) without the use of non-toxic solvents. A significant photothermal effect was shown by a 36ºC increment after 10 min of laser irradiation, surpassing reported values for synthetic melanin. A sustained drug release of ca. 23% with photothermal stimuli was observed, compared to 15% without stimuli, after 48 h. This nanoplatform is obtained as a food industry side product, which makes it a natural cost-effective biomedical material. Natural MPs were applied in an osteosarcoma cell line (SaOs-2), and internalized by the cells in less than 2 h, showing cytocompatibility up to 1000 µg/mL after 72 h of contact with cells. On the contrary, when natural MNPs loaded with Dox (Dox-MNPs) were placed in contact with the SaOs-2 cells and were simultaneously receiving NIR light it was observed a 93% reduction in cancer cells in 48 h, revealing a synergistic effect between chemotherapy and phototherapy. To our knowledge this is the first time that natural MNPs extracted from Sepia officinalis were tested on an osteosarcoma cell line as chemo-photothermal agent, showing these NPs are an effective, cost-effective, reproducible, non-toxic nanoplatform for osteosarcoma treatment using combined effects.

Efficacy of melanin-loaded lipoic acid-modified chitosan hydrogel in diabetic wound healing

The healing of diabetic wounds is significantly impeded due to severe oxidative stress and hindered angiogenesis, presenting a major challenge to clinical treatment. In this context, we introduces a novel hydrogel dressing strategy that uniquely combines α-lipoic acid-modified chitosan (LAMC) and melanin nanoparticles (MNPs). This innovative hydrogel, LAMC@MNPs, is formulated to gel under ultraviolet (UV) light without the need for a photoinitiator, simplifying the preparation process and potentially enhancing safety. Our experimental results demonstrate that the LAMC@MNPs hydrogel not only exhibits superior skin adhesion, with an average strength of 56.59 ± 3.16 KPa, but also effectively alleviates oxidative stress and accelerates vascular regeneration and wound healing. This is achieved by promoting cell migration and scavenging free radicals, addressing the critical barriers in diabetic wound care. The combination of these materials and their functional benefits presents a promising new approach to diabetic wound treatment.

Endogenous Melanin and Hydrogen-Based Specific Activated Theranostics Nanoagents: A Novel Multi-Treatment Paradigm for Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a systemic autoimmune disorder characterized by excessive proliferation of rheumatoid arthritis synovial fibroblasts (RASFs) and accumulation of inflammatory cytokines. Exploring the suppression of RASFs and modulation of the RA microenvironment is considered a comprehensive strategy for RA. In this work, specifically activated nanoagents (MAHI NGs) based on the hypoxic and weakly acidic RA microenvironment are developed to achieve a second near-infrared fluorescence (NIR-II FL)/photoacoustic (PA) dual-model imaging-guided multi-treatment. Due to optimal size, the MAHI NGs passively accumulate in the diseased joint region and undergo rapid responsive degradation, precisely releasing functionalized components: endogenous melanin-nanoparticles (MNPs), hydrogen gas (H2), and indocyanine green (ICG). The released MNPs play a crucial role in ablating RASFs within the RA microenvironment through photothermal therapy (PTT) guided by accurate PA imaging. However, the regional hyperthermia generated by PTT may exacerbate reactive oxygen species (ROS) production and inflammatory response following cell lysis. Remarkably, under the acidic microenvironment, the controlled release of H2 exhibits precise synergistic antioxidant and anti-inflammatory effects with MNPs. Moreover, the ICG, the second near-infrared dye currently approved for clinical use, possesses excellent NIR-II FL imaging properties that facilitate the diagnosis of deep tissue diseases and provide the right time-point for PTT.

Marine biomass-derived PDMS-based composite sponge for sustainably sourced solar-driven interfacial evaporation

Solar-driven interface evaporation has emerged as an attractive technology for addressing the pressing issue of water scarcity. Herein, from the perspective of utilizing and managing ocean resources, we have developed a comprehensive evaporator based on ocean biomass for efficient solar-driven interfacial evaporation, aiming to sustainably harness marine resources. The construction of a biomass-based evaporator was achieved using three-dimensional melanin nanoparticles (MNPs)@carboxymethyl chitosan (CMCS)/polydimethylsiloxane (PDMS) porous sponge, which exhibits highly hydrophilic and porous properties. In this study, MNPs functioned as the photothermal material and the CMCS-hydrophilic modified PDMS sponge was utilized as the supportive material. Owing to its outstanding photothermal conversion capability and ingeniously designed columnar shape with cold evaporation surface, the MCP sponge-based evaporator achieves a water evaporation rate of 2.04 kg·m−2·h−1 and an evaporation efficiency of 85% under 1sun illumination. In addition, the MCP sponge-based evaporator exhibits an outstanding desalination performance (93% salt rejection) and purification efficiency for dyes with natural sunlight. This groundbreaking study presents an innovative method by utilizing marine biomass-derived CMCS and MNPs as raw materials to construct a high-performance solar-driven interface evaporator, thereby tackling clean water generation and promoting the sustainability of marine ecosystems.

Immunomodulatory melanin@Pt nanoparticle-reinforced adhesive hydrogels for healing diabetic oral ulcers

Oral ulcers may be addressed with various biomaterials infused with medications or cytokines. However, many patients derive little advantage from these substances due to inadequate adhesion, brief retention in the mouth, and diminished drug effectiveness. Here, we introduce a hydrogel patch (MPG3) consisting of a biopolymer matrix with light-activated adhesion features infused with platinum-decorated melanin nanoparticles that possess healing-promoting abilities. Initially, through straightforward local application, an adhesive hydrogel barrier forms over mucosal imperfections upon exposure to ultraviolet light. Following this, MPG3 exhibits outstanding oxygen production and reactive oxygen species elimination properties. These capabilities contribute to regulating the wound microenvironment, thereby expediting the wound's transition from the inflammatory to the proliferative stage. In rat models of oral ulcers, the MPG3 patch hastens recovery by modulating the inflammatory milieu of the damaged tissue and fostering expedited re-epithelialization and blood vessel formation. Conclusively, this light-activated adhesive hydrogel shows promise for swift wound healing and could revolutionize therapeutic approaches for treating clinical oral ulcers, especially in diabetic patients.

A kidney-targeted chitosan-melanin nanoplatform for alleviating diabetic nephropathy through modulation of blood glucose and oxidative stress

Diabetic nephropathy (DN) is a serious complication in patients with diabetes, whose expansion process is closely related to oxidative stress caused by hyperglycemia. Herein, we report a chitosan-targeted dagliflozin-loaded melanin nanoparticle (CSMDNPs) that can selectively accumulate in injured kidneys, reduce blood glucose, and alleviate the oxidative stress-induced damage. CSMDNPs possess good dispersion and physiological stability, responsive release at acidic pH, and strong scavenging activities for various reactive oxygen and reactive nitrogen radicals. Moreover, in vitro experiments confirm that CSMDNPs have good biocompatibility, enable targeted uptake in NRK-52E renal tubular cells, and also well alleviate high glucose-induced oxidative stress. In the STZ-induced DN model, CSMDNPs exhibit high targeting distribution and retention in the damaged kidneys of DN mice according to photoacoustic imaging. At the end of CSMDNPs treatment, DN mice show a decrease in fasting blood glucose and a return to near-normal urine and blood indices. H&E, PAS, and masson pathological staining also indicates that CSMDNPs significantly inhibit the expansion of renal interstitium, glycogen, and collagen deposition, showing excellent therapeutic effects. In addition, melanin acts as both drug carrier and antioxidant without exogenous carrier introduction, exhibiting better biosafety and translational prospects.