Microwave-Induced Chemotoxicity of Polydopamine-Coated Magnetic Nanocubes

Polydopamine-coated FeCo nanocubes (PDFCs) were successfully synthesized and tested under microwave irradiation of 2.45 GHz frequency and 0.86 W/cm² power. These particles were found to be non-toxic in the absence of irradiation, but gained significant toxicity upon irradiation. Interestingly, no increase in relative heating rate was observed when the PDFCs were irradiated in solution, eliminating nanoparticle (NP)-induced thermal ablation as the source of toxicity. Based on these studies, we propose that microwave-induced redox processes generate the observed toxicity.     

High-Resolution Patterned Functionalization of Slippery “Liquid-Like” Brush Surfaces via Microdroplet-Confined Growth of Multifunctional Polydopamine Arrays

Slippery omniphobic covalently attached liquids enable smooth, transparent, pressure- and temperature-resistant, and liquid-repellent coatings. Patterned functionalization of such surfaces would drive technology developments and fundamental understandings in broad applications from biosensors to sustainable smart surfaces. Herein an additive microcontact printing approach in combination with the microdroplet-confined synthesis is developed to functionalize slippery surfaces tethered with “liquid-like” linear poly(dimethylsiloxane) by multifunctional polydopamine (PDA) arrays. Using glycerol and non-ionic surfactant Tween-20, microdroplet arrays containing dopamine monomers are printed onto the slippery surfaces and serve as microreactors for the in situ growth of PDA micropatterns. The confined growth approach enables tunable feature size, height, and morphology of the patterns, through which sub-micrometer PDA dot arrays over centimeter-square patterning area can be reliably achieved. Furthermore, the reactive and hydrophilic PDA micropatches allow further functionalization of the slippery surfaces with a diverse variety of materials, meanwhile the anti-fouling and dynamically dewetting “liquid-like” brushes permit minimum background contamination. Proof-of-concept demonstrations include PDA-initiated photografting for stimuli-responsive polymer functionalization, protein immobilization for microarray-based immunoassays, as well as sliding-induced selective dewetting of organic solutions to pattern photoluminescent perovskite microcrystals and nanoparticles. The current approach illustrates the potential for applying patterned slippery surfaces with multifunctional architectures in many fields.     

Effect of electron beam irradiation on polydopamine and its application in polymer solar cells

Polydopamine (PDA) films were irradiated by an electron beam linear accelerator at different irradiation doses ranging from 10 to 150 kGy. The irradiated samples were characterized by Fourier transform infrared spectrometry, UV‐Vis, scanning electron microscopy, atomic force microscope, X‐ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, and thermogravimetric analysis. Changes in surface morphology, chemical structure, contact angle, frontier orbitals, and bandgap were analyzed. PDA films modified by electron beam irradiation were used in the interface design and control of polymer solar cells. Devices with the structures of ITO/ZnO/PTB7:PC₇₁BM/MoO₃/Al and ITO/PDA‐ZnO/PTB7:PC₇₁BM/MoO₃/Al were fabricated. The solar cells with a 100‐kGy electron beam‐irradiated PDA film‐modified ZnO electron transport layer had a significantly improved short circuit current density, and its efficiency reached a maximum value. The short circuit current density and power conversion efficiency reached 13.70 mA/cm² and 3.82%, respectively. Electron beam irradiation is an effective method to modify PDA, which can be used as an interface modifier in polymer solar cells.     

Facile Fabrication of Conductive Paper-based Materials from Tunicate Cellulose Nanocrystals and Polydopamine-decorated Graphene Oxide

Conductive papers made from graphene and its derivatives are important for the development of electronic devices; however, elastomerbased matrices usually make it difficult for the conductive sheets to form continuous conductive networks. In this work, we used tunicate-derived cellulose nanocrystals(TCNC) instead of traditional elastomers as the matrix for polydopamine(PDA)-coated and reduced graphene oxide(GO) to prepare conductive paper, which, at a low concentration, were better for the formation of conductive networks from conductive sheets. It was found that the Young's modulus of the conductive paper produced via this strategy reached as high as 7 GPa. Meanwhile, owing to the partial reduction of GO during the polymerization of dopamine, the conductivity of the conductive paper reached as high as 1.3×10-5 S/cm when the PDA-coated GO content was 1 wt%, which was much higher than the conductivity of pure GO(～4.60×10-8 S/cm). This work provides a new strategy for preparing environmentally friendly conductive papers with good mechanical properties and low conductive filler content, which may be used to produce high-performance, low-cost electronic devices.     

Polydopamine as a Biocompatible Multifunctional Nanocarrier for Combined Radioisotope Therapy and Chemotherapy of Cancer

Development of biodegradable nanomaterials for drug delivery and cancer theranostics has attracted great attention in recent years. In this work, polydopamine (PDA), a biocompatible polymer, is developed as a promising carrier for loading of both radionuclides and an anticancer drug to realize nuclear‐imaging‐guided combined radioisotope therapy (RIT) and chemotherapy of cancer in one system. It is found that PDA nanoparticles after modification with poly(ethylene glycol) (PEG) can successfully load several different radionuclides such as ^99mTc and ¹³¹I, as well as an anticancer drug doxorubicin (DOX). While labeling PDA‐PEG with ^99mTc (^99mTc‐PDA‐PEG) enables in vivo single photon emission computed tomography imaging, nanoparticles co‐loaded with ¹³¹I and DOX (¹³¹I‐PDA‐PEG/DOX) can be utilized for combined RIT and chemotherapy, which offers effective cancer treatment efficacy in a remarkably synergistic manner, without rendering significant toxicity to the treated animals. Therefore, this study presents an interesting class of biocompatible nanocarriers, which allow the combination of RIT and chemotherapy, the two extensively applied cancer therapeutic strategies, promising for future clinic translations in cancer treatment.     

pH值响应性羧甲基琼脂糖-聚多巴胺水凝胶制备及缓释性能

开发一种pH值响应性羧甲基琼脂糖-聚多巴胺（carboxymethyl agarose-polydopamine,CMA-PDA）水凝胶载体。通过氯乙酸取代法合成了CMA。采用红外光谱、核磁共振、电子显微镜和热重分析对CMA的理化性质进行表征。进一步通过冷凝方法制备CMA-PDA水凝胶,系统研究CMA-PDA水凝胶的流变性能和质构性能进行表征。结果表明,PDA的加入提高了水凝胶的凝胶强度、硬度和黏弹性。以阿霉素为模型,研究该水凝胶在pH 2.0、6.2、6.8、7.4条件下的释放行为,表明其具有较好的pH值响应性,pH 2.0条件下的释放率显著高于其他条件。同时以L929细胞为模型,研究该水凝胶的生物相容性,表明其无明显细胞毒性。这项研究证明了CMA-PDA水凝胶生物相容性良好,具有pH值响应性和缓释性能,可以作为潜在的生物活性物质递送载体。     

Antibiotic-decorated titanium with enhanced antibacterial activity through adhesive polydopamine for dental/bone implant

Implant-associated infections, which are normally induced by microbial adhesion and subsequent biofilm formation, are a major cause of morbidity and mortality. Therefore, practical approaches to prevent implant-associated infections are in great demand. Inspired by adhesive proteins in mussels, here we have developed a novel antibiotic-decorated titanium (Ti) material with enhanced antibacterial activity. In this study, Ti substrate was coated by one-step pH-induced polymerization of dopamine followed by immobilization of the antibiotic cefotaxime sodium (CS) onto the polydopamine-coated Ti through catechol chemistry. Contact angle measurement and X-ray photoelectron spectroscopy confirmed the presence of CS grafted on the Ti surface. Our results demonstrated that the antibiotic-grafted Ti substrate showed good biocompatibility and well-behaved haemocompatibility. In addition, the antibiotic-grafted Ti could effectively prevent adhesion and proliferation of Escherichia coli (Gram-negative) and Streptococcus mutans (Gram-positive). Moreover, the inhibition of biofilm formation on the antibiotic-decorated Ti indicated that the grafted CS could maintain its long-term antibacterial activity. This modified Ti substrate with enhanced antibacterial activity holds great potential as implant material for applications in dental and bone graft substitutes.     

A Lithium‐Sulfur Battery with a High Areal Energy Density

The battery community has recently witnessed a considerable progress in the cycle lives of lithium‐sulfur (Li‐S) batteries, mostly by developing the electrode structures that mitigate fatal dissolution of lithium polysulfides. Nonetheless, most of the previous successful demonstrations have been based on limited areal capacities. For realistic battery applications, however, the chronic issues from both the anode (lithium dendrite growth) and the cathode (lithium polysulfide dissolution) need to be readdressed under much higher loading of sulfur active material. To this end, the current study integrates the following three approaches in a systematic manner: 1) the sulfur electrode material with diminished lithium polysulfide dissolution by the covalently bonded sulfur‐carbon microstructure, 2) mussel‐inspired polydopamine coating onto the separator that suppresses lithium dendrite growth by wet‐adhesion between the separator and Li metal, and 3) addition of cesium ions (Cs⁺) to the electrolyte to repel incoming Li ions and thus prevent Li dendrite growth. This combined strategy resolves the long‐standing problems from both electrodes even under the very large sulfur‐carbon composite loading of 17 mg cm^?2 in the sulfur electrode, enabling the highest areal capacity (9 mAh cm^?2) to date while preserving stable cycling performance.     

AZ31镁合金表面聚多巴胺/羟基磷灰石复合膜层的耐蚀性研究

通过两步湿化学沉淀法,在AZ31镁合金表面制备了聚多巴胺/羟基磷灰石复合涂层。使用扫描电子显微镜 (SEM),原子力显微镜 (AFM),X射线光电子能谱 (XPS),X射线衍射仪 (XRD) 及傅里叶红外仪 (FT-IR) 等表征了样品的形貌及结构。结果表明,聚多巴胺膜层平滑致密,经聚多巴胺诱导沉积的羟基磷灰石膜为交错排列的片状羟基磷灰石垂直阵列。利用电化学极化曲线和阻抗谱表征了聚多巴胺/羟基磷灰石复合膜的耐蚀性能,结果显示复合膜使AZ31镁合金在SBF溶液中的耐腐蚀性能明显提高。