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Polydopamine (PDA) nanoparticles have emerged as an attractive biomimetic photothermal agent in photothermal antibacterial therapy due to their ease of synthesis, good biodegradability, long‐term safety, and excellent photostability. However, the therapeutic effects of PDA nanoparticles are generally limited by the low photothermal conversion efficiency (PCE). Herein, PDA@Ag nanoparticles are synthesized via growing Ag on the surface of PDA nanoparticles and then encapsulated into a cationic guar gum (CG) hydrogel network. The optimized CG/PDA@Ag platform exhibits a high PCE (38.2%), which is more than two times higher than that of pure PDA (16.6%). More importantly, the formulated CG/PDA@Ag hydrogel with many active groups can capture and kill bacteria through effective interactions between hydrogel and bacteria, thereby benefiting the antibacterial effect. As anticipated, the designed CG/PDA@Ag system combined the advantages of PDA@Ag nanoparticles (high PCE) and hydrogel (preventing aggregation of PDA@Ag nanoparticles and possessing inherent antibacterial ability) is demonstrated to have superior antibacterial efficacy both in vitro and in vivo. This study develops a facile approach to boost the PCE of PDA for photothermal antibacterial therapy, providing a significant step forward in advancing the application of PDA nano‐photothermal agents. This work presents a facile and convenient strategy to boost the photothermal conversion efficiency of polydopamine (PDA) nanomaterials via growing Ag nanoparticles on the surface of PDA and then encapsulated into a cationic guar gum hydrogel network. The resultant system possesses robust photothermal performance that effectively kills bacteria and promotes wound healing.

Polydopamine (PDA), as a mussel-inspired material, exhibits numerous favorable performance characteristics, such as a simple preparation process, prominent photothermal transfer efficiency, excellent biocompatibility, outstanding drug binding ability, and strong adhesive properties, showing great potential in the biomedical field. The rapid development of this field in the past few years has engendered substantial progress in PDA antibacterial materials. This review presents recent advances in PDA-based antimicrobial materials, including the preparation methods and antibacterial mechanisms of free-standing PDA materials and PDA-based composite materials. Furthermore, the urgent challenges and future research opportunities for PDA antibacterial materials are discussed.

Synthesis of surface modified/multi-functional nanoparticles has become a vital research area of material science. In the present work, iron oxide (Fe3O4) nanoparticles prepared by solvo-thermal method were functionalized by polydopamine. The catechol groups of polydopamine at the surface of nanoparticles provided the sites for the attachment of Aspergillus terreus AH-F2 lipase through adsorption, Schiff base and Michael addition mechanisms. The strategy was revealed to be facile and efficacious, as lipase immobilized on magnetic nanoparticles grant the edge of ease in recovery with utilizing external magnet and reusability of lipase. Maximum activity of free lipase was estimated to be 18.32 U/mg/min while activity of Fe3O4-PDA-Lipase was 17.82 U/mg/min (showing 97.27% residual activity). The lipase immobilized on polydopamine coated iron oxide (Fe3O4_PDA_Lipase) revealed better adoptability towards higher levels of temperature/pH comparative to free lipase. The synthesized (Fe3O4_PDA_Lipase) catalyst was employed for the preparation of biodiesel from waste cooking oil by enzymatic transesterification. Five factors response surface methodology was adopted for optimizing reaction conditions. The highest yield of biodiesel (92%) was achieved at 10% Fe3O4_PDA_Lipase percentage concentration, 6:1 CH3OH to oil ratio, 37 °C temperature, 0.6% water content and 30 h of reaction time. The Fe3O4-PDA-Lipase activity was not very affected after first four cycles and retained 25.79% of its initial activity after seven cycles. The nanoparticles were characterized by FTIR (Fourier transfer infrared) Spectroscopy, XRD (X-ray diffraction) and TEM (transmission electron microscopy), grafting of polydopamine on nanoparticles was confirmed by FTIR and formation of biodiesel was evaluated by FTIR and GC-MS (gas chromatography-mass spectrometry) analysis.

Polydopamine (PDA), the final oxidation product of dopamine or other catecholamines, attracted much attention as versatile coatings that can be used to cover the surface of almost all materials with a conformal layer of adjustable thickness ranging from a few to about 100 nm. These PDA layers can be subsequently modified with molecules carrying nucleophilic groups or with metallic nanoparticles from solutions containing metallic cations. However, during the deposition of PDA film on the surfaces, the reaction products that are simultaneously obtained from the oxidation of catecholamines in solution precipitate. Hence, some recent effort has been devoted to produce PDA in the form of nanoparticles. The aim of this short review is to give a comprehensive description of the synthesis methods yielding of PDA nanoparticles in the absence or in the presence of templating agents (polymers, polyelectrolytes, surfactants, proteins, and even some small organic molecules). We will also describe the use of thin PDA layers to coat already synthesized nanoparticles or nanotubes. Finally, several first applications of the obtained PDA nanoparticles will be described.

As a novel 2D material, black phosphorus (BP) nanosheets are considered as a promising candidate for drug delivery platform for synergistic chemo/photothermal therapy. However, the intrinsic instability of bare BP poses a challenge in its biomedical applications. To date, some strategies have been employed to prevent BP from rapid ambient degradation. Unfortunately, most of these strategies are not suitable for the drug delivery systems. Here, a simple polydopamine modification method is developed to enhance the stability and photothermal performance of bare BP nanosheets. Then, this nanocapsule is used as a multifunctional codelivery system for the targeted chemo, gene, and photothermal therapy against multidrug‐resistant cancer. The enhanced tumor therapy effect is demonstrated by both in vitro and in vivo studies. A simple polydopamine modification method is developed to enhance the stability and photothermal performance of bare black phosphorus nanosheets. Then, this nanocapsule is used as a multifunctional codelivery system for the targeted chemo, gene, and photothermal therapy against multidrug‐resistant cancer. The enhanced tumor therapy effect is demonstrated by both in vitro and in vivo studies.

Polyphenols, due to their high biocompatibility and wide occurrence in nature, have attracted increasing attention in the engineering of functional materials ranging from films, particles, to bulk hydrogels. Colloidal particles, such as nanogels, hollow capsules, mesoporous particles and core-shell structures, have been fabricated from polyphenols or their derivatives with a series of polymeric or biomolecular compounds through various covalent and non-covalent interactions. These particles can be designed with specific properties or functionalities, including multi-responsiveness, radical scavenging capabilities, and targeting abilities. Moreover, a range of cargos (e.g., imaging agents, anticancer drugs, therapeutic peptides or proteins, and nucleic acid fragments) can be incorporated into these particles. These cargo-loaded carriers have shown their advantages in the diagnosis and treatment of diseases, especially of cancer. In this review, we summarize the assembly of polyphenol-based particles, including polydopamine (PDA) particles, metal-phenolic network (MPN)-based particles, and polymer-phenol particles, and their potential biomedical applications in various diagnostic and therapeutic applications.

Bioinspired Structurally Colored Materials The striking coloration in the natural world is typically caused by light interference at nanostructured materials and the broadband light absorption of melanin pigments. In article 2300986, Nico Nees, Nicolas Vogel, and co‐workers use colloidal photonic crystals containing polydopamine as synthetic mimics of this structural coloration and investigate the total amount of absorber and the way of its incorporation to create the most saturated structural coloration.

Osteoarthritis (OA) is marked by cartilage deterioration, subchondral bone changes, and an inflammatory microenvironment. The study introduces the Microneedle‐Delivered Polydopamine‐Exosome (PDA@Exo MN), a therapeutic that not only preserves cartilage and promotes bone regeneration but also improves localized drug delivery through enhanced penetration capabilities. PDA@Exo MN shows strong reactive oxygen species (ROS) scavenging abilities and high biocompatibility, fostering osteogenesis and balancing anabolic and catabolic processes in cartilage. It directs macrophage polarization from M0 to the anti‐inflammatory M2 phenotype. RNA sequencing of treated chondrocytes demonstrates restored cellular function and activated antioxidant responses, with modulated inflammatory pathways. The PI3K‐AKT‐mTOR pathway's activation, essential for PDA@Exo's effects, is confirmed via bioinformatics and Western blot. In vivo assessments robustly validate that PDA@Exo MN prevents cartilage degradation and OA progression, supported by histological assessments and micro‐CT analysis, highlighting its disease‐modifying impact. The excellent biocompatibility of PDA@Exo MN, verified through histological (H&E) and blood tests showing no organ damage, underscores its safety and efficacy for OA therapy, making it a novel and multifunctional nanomedical approach in orthopedics, characterized by organ‐friendliness and biosecurity. Introducing Microneedle‐Delivered Polydopamine‐Exosome (PDA@Exo MN), a novel osteoarthritis therapeutic with enhanced drug delivery via improved penetration. Demonstrating strong antioxidative properties and high biocompatibility, PDA@Exo MN preserves cartilage, promotes bone regeneration, and effectively modulates inflammatory pathways to halt disease progression.

Surface modification is an important approach to modify the properties of materials. Numerous approaches have been adopted to tailor the properties of such materials, which have been proven successful at many scales and parameters. However, most of these techniques are often tedious, poorly adhesive, costly, sometimes hazardous, and surface‐specific, hence cannot be extended on a large scale and all kinds of surfaces. These shortcomings have led to the emergence of new dopamine (DA) based green surface modification technique where a thin polydopamine (PDA) layer is deposited on surfaces through a facile polymerization of DA under alkaline conditions to enable the surface for various applications. This surface modification strategy has several advantages over other techniques in deposition processing under mild conditions, cost‐effective and straightforward ingredients, and applicability to all kinds of surfaces regardless of their sizes, shapes, and types. Moreover, the PDA layer enhances the surface functionality. Therefore, it can serve as a versatile platform for various secondary reactions for a wide range of applications. Herein, the chemistry of DA is summarized and its polymerized form PDA for the modification of different families of materials’ surfaces with an emphasis on energy, environmental and biological applications. Surface modification is one of the compelling strategies in ensuring the diverse applications of polydopamine in emerging fields e.g., electrochemical energy storage, conversion, photothermal therapy, bioengineering, adhesives, purification, sensors, and environment protection. In this review, the chemistry of dopamine is summarized and its polymerized form polydopamine for the modification of different families of materials’ surfaces with an emphasis on energy, environmental and biological applications.