Oxidation-controlled synthesis of fluorescent polydopamine for the detection of metal ions

An Iron-Based Metal-Organic Framework as Nanocarrier for Lambda-Cyhalothrin Delivery: pH-Responsive Controlled Release, Enhanced Leaf Adhesion, and Prolonged Duration Period against Culex pipiens pallens

Lambda-Cyhalothrin (LC) is a high-efficiency and broad-spectrum insecticide. However, due to its poor water dispersion stability and unstable efficacy, it has many problems in practical applications. Therefore, there is an urgent need to develop new formulations with stability, low toxicity, and environmental friendliness to overcome the drawbacks of traditional pesticide formulations. This study designed an iron-based metal-organic framework (MIL-101(Fe)) as a nanocarrier for the loading of LC and then surface modified it with polydopamine (PDA) to form the nanopesticide PDA-LC-MIL. The results showed that PDA-LC-MIL has good stability and can achieve controlled release of pesticide by adjusting the pH value. In addition, it also has a good leaf affinity and can effectively adhere on crop leaves, improving the utilization rate of pesticides. The insecticidal experimental results indicate that PDA-LC-MIL has significantly improved sustained insecticidal activity. PDA-LC-MIL also has good biocompatibility and shows no significant inhibitory effect on seed germination and seedling growth of Vigna radiata (L.) Wilczek and maize. Therefore, we firmly believe that MIL-based nanopesticides will have broad application prospects in the field of green pesticides and modern agriculture.

Enhanced bone regeneration via surface functionalization of biphasic calcium phosphate scaffolds with dopamine-modified hyaluronic acid hydrogel or mg-doped calcium silicate

Rapid induction of angiogenesis is crucial for the treatment of large bone defects and accelerating the material-mediated bone defect repair process. In this study, we employed a negative pressure infiltration method to coat the surface of porous BCP scaffolds with dopamine-modified hyaluronic acid (HA-DA) hydrogel and magnesium-doped calcium silicate (Mg-CS). In vitro results demonstrated that HA-DA hydrogel coating with an appropriate degree of dopamine grafting significantly improved the in vitro angiogenic activity of BCP scaffolds without affecting their osteogenic activity. The Mg-CS coating, heat-treated to ensure good combination with the BCP matrix, could sustainably release angiogenic silicon ions and osteogenic magnesium ions. Results from rat cranial defect repair showed that the implanted BCP@HA-DA-2 and BCP@10 Mg-CS scaffolds further accelerated the occurrence and development of neovascularization at the defect site, facilitating new bone formation. Among them, BCP@10 Mg-CS scaffold exhibited the best bone defect repair effect and has the potential for clinical application.

M1 macrophage membrane-coated nickel-arsenic nanocomplex promoting synergistic treatment of hepatocellular carcinoma

By inducing apoptosis, promoting differentiation and reducing the migration of cancer cells, arsenic has a higher therapeutic effect and lower risk of recurrence and metastasis than conventional anticancer drugs. However, the low bioavailability and adverse side effects of arsenic hinder its application in hepatocellular carcinoma (HCC). Therefore, a M1 macrophage membrane-coated nickel-arsenic/polydopamine nanocomplex (NiAsOx@P@M) was constructed to enhance the combined antitumor effects of chemotherapy and immunotherapy. The nanocomplex consisted of a nickel-arsenic oxide core, a polydopamine (PDA) shell and a M1 macrophage membrane (MM) coating. MM endowed the nanocomplex with natural tumor homing and immune escape properties, and the nanocomplex was gradually accumulated in the tumor tissue during the internal circulation. The acid response of PDA led to its degradation in the tumor microenvironment (TME). The degradation product dopamine (DA) and MM jointly promoted tumor immunity and regulated tumor-associated macrophages (TAMs) to repolarization M1 phenotype. The nickel-arsenic oxide core dissociated in an acid environment and released arsenic, thus killing tumor cells. In summary, the nanocomplex provided a promising delivery strategy for arsenic therapy of HCC and a novel design idea for the conversion of inorganic drugs into organic preparations.

Metal-chelated polydopamine nanomaterials: Nanoarchitectonics and applications in biomedicine, catalysis, and energy storage

Polydopamine (PDA)-based materials inspired by the adhesive proteins of mussels have attracted increasing attention owing to the universal adhesiveness, antioxidant activity, fluorescence quenching ability, excellent biocompatibility, and especially photothermal conversion capability. The high binding ability of PDA to a variety of metal ions offers a paradigm for the exploration of metal-chelated polydopamine nanomaterials with fantastic properties and functions. This review systematically summarizes the latest progress of metal-chelated polydopamine nanomaterials for the applications in biomedicine, catalysis, and energy storage. Different fabrication strategies for metal-chelated polydopamine nanomaterials with various composition, structure, size, and surface chemistry, such as the pre-functionalization method, the one-pot co-assembly method, and the post-modification method, are summarized. Furthermore, emerging applications of metal-chelated polydopamine nanomaterials in the fields ranging from cancer therapy, theranostics, antibacterial, catalysis to energy storage are highlighted. Additionally, the critical remaining challenges and future directions of this area are discussed to promote the further development and practical applications of PDA-based materials.

Preparation and characterization of mussel-inspired chitosan/polydopamine films and their feasibility for oral mucosa application

Oral mucosal lesions (OML), which represent a major public health issue worldwide, include any pathological changes in the oral mucosa, such as ulcers, pigmentation, and swelling. Due to its humid and dynamic complex environment, designing oral mucosal preparations poses significant challenges. Drawing inspiration from mussels, this study employed an eco-friendly one-pot strategy for the preparation of chitosan/polydopamine (CS/PDA) films. We demonstrated that CS-induced polymerization of dopamine monomers under acidic conditions, which might be attributed to the large number of hydrogen bonding sites of CS chains. PDA markedly enhances properties of the CS film and exhibits concentration dependence. At the concentration of 1 wt% PDA, the lap-shear strength and tensile strength of CS/PDA films reached 5.01 ± 0.24 kpa and 4.20 ± 0.78 kpa, respectively, indicating that the mucosal adhesion ability was significantly improved. In comparison with the single CS film, the swelling rate of CS/PDA film decreased by about 30 %. Rheological results also showed that the storage modulus returned to 93 % after cyclic large strain, while the single CS film only recovered to 73 %. Moreover, these films demonstrated good biocompatibility and enhanced oral ulcer healing in rats, providing a new and practical option for the local treatment of OML.

One-pot hydrothermal synthesis of silicon, nitrogen co-doped carbon dots for enhancing enzyme activity of acid phosphatase (ACP) to dopamine and for cell imaging

Developing water-soluble nanomaterials with high photoluminescence emission and high yield for biological analysis and imaging is urgently needed. Herein, water-soluble blue emitting silicon and nitrogen co-doped carbon dots (abbreviated as Si-CDs) of a high photoluminescence quantum yield of 80 % were effectively prepared with high yield rate (59.1 %) via one-step hydrothermal treatment of N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAMO) and trans-aconitic acid. Furthermore, the Si-CDs demonstrate environmental robustness, photo-stability and biocompatibility. Given the importance of the potentially abnormal levels of acid phosphatase (ACP) in cancer diagnosis, developing a reliable and sensitive ACP measurement method is of significance for clinical research. The Si-CDs unexpectedly promote the catalytic oxidation of ACP on dopamine (DA) to polydopamine under acidic conditions through the produced reactive oxygen species (ROS). Correspondingly, a fluorescence response strategy using Si-CDs as the dual functions of probes and promoting enzyme activity of ACP on catalyzing DA was constructed to sensitively determine ACP. The quantitative analysis of ACP displayed a linear range of 0.1-60 U/L with a detection limit of 0.056 U/L. The accurate detection of ACP was successfully achieved in human serum through recovery tests. As a satisfactory fluorescent probe, Si-CDs were successfully applied to fluorescent imaging of A549 cells in cytoplasmic with long-term and safe staining. The Si-CDs have the dual properties of outstanding fluorescent probes and auxiliary oxidase activity, indicating their great potential in multifunctional applications.

Advancements in the Application of the Fenton Reaction in the Cancer Microenvironment

Cancer is a complex and multifaceted disease that continues to be a global health challenge. It exerts a tremendous burden on individuals, families, healthcare systems, and society as a whole. To mitigate the impact of cancer, concerted efforts and collaboration on a global scale are essential. This includes strengthening preventive measures, promoting early detection, and advancing effective treatment strategies. In the field of cancer treatment, researchers and clinicians are constantly seeking new approaches and technologies to improve therapeutic outcomes and minimize adverse effects. One promising avenue of investigation is the utilization of the Fenton reaction, a chemical process that involves the generation of highly reactive hydroxyl radicals (·OH) through the interaction of hydrogen peroxide (H2O2) with ferrous ions (Fe2+). The generated ·OH radicals possess strong oxidative properties, which can lead to the selective destruction of cancer cells. In recent years, researchers have successfully introduced the Fenton reaction into the cancer microenvironment through the application of nanotechnology, such as polymer nanoparticles and light-responsive nanoparticles. This article reviews the progress of the application of the Fenton reaction, catalyzed by polymer nanoparticles and light-responsive nanoparticles, in the cancer microenvironment, as well as the potential applications and future development directions of the Fenton reaction in the field of tumor treatment.

Polydopamine-based nanozyme with dual-recognition strategy-driven fluorescence-colorimetric dual-mode platform for Listeria monocytogenes detection

Development of a simple and efficient dual-mode analytical technique with the built-in cross reference correction feature is benefit to achieve the highly accurate detection of the target pollutants and avoid the false-positive outputs in environmental media. Here, we synthesized a Fe-doped polydopamine (Fe@PDA)-based nanozyme with prominent peroxide-mimetic enzyme activity and high fluorescence emission ability. On this basis, we designed a dual-recognition strategy-driven fluorescence-colorimetric dual-mode detection platform, consisting of Listeria monocytogenes (L. monocytogenes) recognition aptamer-modified Fe@PDA (apt/Fe@PDA) and vancomycin-functionalized Fe₃O₄ (van/Fe₃O₄), for L. monocytogenes. Owing to van/Fe₃O₄-powered magnetic separation, there was a L. monocytogenes concentration-dependent fluorescence enhancement of apt/Fe@PDA for performing fluorescence assay in the precipitate. In this case, the prominent peroxide-mimetic enzyme activity of the residual apt/Fe@PDA in the precipitation could catalyze H₂O₂ to further oxidate colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxTMB, which displayed a L. monocytogenes concentration-dependent absorbance enhancement for carrying out colorimetric assay as well. As a result, a fluorescence-colorimetric dual-mode analytical platform was proposed to successfully detect the residual L. monocytogenes in real environmental media with acceptable results. This work showed the great prospects by integrating dual-recognition strategy into fluorescence nanozyme to develop efficient and reliable dual-mode analytical platforms for safeguarding environmental health.

Recent Advances in Intrinsically Fluorescent Polydopamine Materials

Fluorescence nanoparticles have gained much attention due to their unique properties in the sensing and imaging fields. Among the very successful candidates are fluorescent polydopamine (FPDA) nanoparticles, attributed to their simplicity in tracing and excellent biocompatibility. This article aims to highlight the recent achievements in FPDA materials, especially on the part of luminescence mechanisms. We focus on the intrinsic fluorescence of PDA and will not discuss fluorescent reaction with a fluorometric reagent or coupling reaction with a fluorophore, which may cause more in vivo interferences. We believe that intrinsic FPDA presents great potential in bioapplications.

Polydopamine as a stable and functional nanomaterial

The mussel inspired chemistry of dopamine leading to versatile coatings on the surface of all kinds of materials in a one pot process was considered as the unique aspect of catecholamine for a long time. Only recently, research has been undertaken to valorize the simultaneous oxidation and colloid formation in dopamine solutions in the presence of an oxidant. This mini review summarizes the synthesis methods allowing to get controlled nanomaterials, either nanoparticles, hollow capsules or nanotubes and even chiral nanomaterials from dopamine solutions. Finally the applications of those nanomaterials will be described.