Hitherto-Unexplored Photodynamic Therapy of Ag2S and Enhanced Regulation Based on Polydopamine In Vitro and Vivo

Given their superior penetration depths, photosensitizers with longer absorption wavelengths present broader application prospects in photodynamic therapy (PDT). Herein, Ag₂S quantum dots were discovered, for the first time, to be capable of killing tumor cells through the photodynamic route by near-infrared light irradiation, which means relatively less excitation of the probe compared with traditional photosensitizers absorbing short wavelengths. On modification with polydopamine (PDA), PDA-Ag₂S was obtained, which showed outstanding capacity for inducing reactive oxygen species (increased by 1.69 times). With the addition of PDA, Ag₂S had more opportunities to react with surrounding O₂, which was demonstrated by typical triplet electron spin resonance (ESR) analysis. Furthermore, the PDT effects of Ag₂S and PDA-Ag₂S achieved at longer wavelengths were almost identical to the effects produced at 660 nm, which was proved by studies in vitro. PDA-Ag₂S showed distinctly better therapeutic effects than Ag₂S in experiments in vivo, which further validated the enhanced regulatory effect of PDA. Altogether, a new photosensitizer with longer absorption wavelength was developed by using the hitherto-unexplored photodynamic function of Ag₂S quantum dots, which extended and enhanced the regulatory effect originating from PDA.     

General Formation of Macro-/Mesoporous Nanoshells from Interfacial Assembly of Irregular Mesostructured Nanounits

Mesoporous core–shell nanostructures with controllable ultra-large open channels in their nanoshells are of great interest. However, soft template-directed cooperative assembly to mesoporous nanoshells with highly accessible pores larger than 30 nm, or even above 50 nm into macroporous range, remains a significant challenge. Herein we report a general approach for precisely tailored coating of hierarchically macro-/mesoporous polymer and carbon shells, possessing highly accessible radial channels with extremely wide pore size distribution from ca. 10 nm to ca. 200 nm, on diverse functional materials. This strategy creates opportunities to tailor the interfacial assembly of irregular mesostructured nanounits on core materials and generate various core–shell nanomaterials with controllable pore architectures. The obtained Fe,N-doped macro-/mesoporous carbon nanoshells show enhanced electrochemical performance for the oxygen reduction reaction in alkaline condition.     

Tribological behaviors of a novel trilayer nanofilm: the influence of outer chain length and interlayer thickness

Polydopamine (coded as PDA) is reported to be very adhesive and reactive due to the attached functional groups, such as amine and hydroxyl groups. In this work, taking advantage of the condensation between Si–OH of the hydroxylated alkyltrichlorosilane (ATS) and C–OH on PDA surface, ATS molecules with different chain carbon number of 10, 14 and 18 were grafted onto the 3‐aminopropyl triethoxysilane (APTES)‐PDA dual‐layer film, which was composed of PDA outerlayer and APTES underlayer, on Si substrate. Thus, hydrophobic trilayer films coded as APTES‐PDA‐ATS were prepared successfully. In order to reveal the dependence of the tribological behaviors upon the microstructures of the film, tribological experiments were conducted on an atomic force microscope and a ball‐on‐plate tribometer. Experimental results showed that the (micro‐) friction reducing (characterized by a parameter of relative friction coefficient or friction coefficient, RFC or FC) and macro‐wear resisting (characterized by anti‐wear life) behaviors were related with the chain length of outerlayer and the PDA thickness. Specifically, on one hand, as the chain length increases, RFC/FC decreased and macro anti‐wear life lengthened; on the other hand, as PDA gets thicker, RFC increased and the anti‐wear life enhanced. Copyright © 2013 John Wiley & Sons, Ltd.     

The Photophysics and Photochemistry of Melanin- Like Nanomaterials Depend on Morphology and Structure

Melanin-like nanomaterials have found application in a large variety of high economic and social impact fields as medicine, energy conversion and storage, photothermal catalysis and environmental remediation. These materials have been used mostly for their optical and electronic properties, but also for their high biocompatibility and simplicity and versatility of preparation. Beside this, their chemistry is complex and it yields structures with different molecular weight and composition ranging from oligomers, to polymers as well as nanoparticles (NP). The comprehension of the correlation of the different compositions and morphologies to the optical properties of melanin is still incomplete and challenging, even if it is fundamental also from a technological point of view. In this minireview we focus on scientific papers, mostly recent ones, that indeed examine the link between composition and structural feature and photophysical and photochemical properties proposing this approach as a general one for future research.     

Zwitterionic Polydopamine Engineered Interface for In Vivo Sensing with High Biocompatibility

Electrochemical sensing performance is often compromised by electrode biofouling (e.g., proteins nonspecific binding) in complex biological fluids; however, the design and construction of a robust biointerface remains a great challenge. Herein, inspired by nature, we demonstrate a robust polydopamine-engineered biointerfacing, to tailing zwitterionic molecules (i.e., sulfobetaine methacrylate, SBMA) through Michael Addition. The SBMA-PDA biointerface can resist proteins nonspecific binding in complex biological fluids while enhancing interfacial electron transfer and electrochemical stability of the electrode. In addition, this sensing interface can be integrated with tissue-implantable electrode for in vivo analysis with improved sensing performance, preserving ca. 92.0% of the initial sensitivity after 2 h of implantation in brain tissue, showing low acute neuroinflammatory responses and good stability both in normal and in Parkinson′s disease (PD) rat brain tissue.     

Silver Nanowires and Silanes in Hybrid Functionalization of Aramid Fabrics

New functionalization methods of meta- and para-aramid fabrics with silver nanowires (AgNWs) and two silanes (3-aminopropyltriethoxysilane (APTES)) and diethoxydimethylsilane (DEDMS) were developed: a one-step method (mixture) with AgNWs dispersed in the silane mixture and a two-step method (layer-by-layer) in which the silanes mixture was applied to the previously deposited AgNWs layer. The fabrics were pre-treated in a low-pressure air radio frequency (RF) plasma and subsequently coated with polydopamine. The modified fabrics acquired hydrophobic properties (contact angle Θ_W of 112–125°). The surface free energy for both modified fabrics was approximately 29 mJ/m², while for reference, meta- and para-aramid fabrics have a free energy of 53 mJ/m² and 40 mJ/m², respectively. The electrical surface resistance (R_s) was on the order of 10² Ω and 10⁴ Ω for the two-step and one-step method, respectively. The electrical volume resistance (R_v) for both modified fabrics was on the order of 10² Ω. After UV irradiation, the Rs did not change for the two-step method, and for the one-step method, it increased to the order of 10¹⁰ Ω. The specific strength values were higher by 71% and 63% for the meta-aramid fabric and by 102% and 110% for the para-aramid fabric for the two-step and one-step method, respectively, compared to the unmodified fabrics after UV radiation.     

Polydopamine-Assisted Rapid One-Step Immobilization of L-Arginine in Capillary as Immobilized Chiral Ligands for Enantioseparation of Dansyl Amino Acids by Chiral Ligand Exchange Capillary Electrochromatography

Herein, a novel L-arginine (L-Arg)-modified polydopamine (PDA)-coated capillary (PDA/L-Arg@capillary) was firstly fabricated via the basic amino-acid-induced PDA co-deposition strategy and employed to constitute a new chiral ligand exchange capillary electrochromatography (CLE-CEC) method for the high-performance enantioseparation of D,L-amino acids (D,L-AAs) with L-Arg as the immobilized chiral ligand coordinating with the central metal ion Zn(II) as running buffer. Assisted by hydrothermal treatment, the robust immobilization of L-Arg on the capillary inner wall could be facilely achieved within 1 h, prominently improving the synthesis efficiency and simplifying the preparation procedure. The successful preparation of PDA/L-Arg coatings in the capillary was systematically characterized and confirmed using several methods. In comparison with bare and PDA-functionalized capillaries, the enantioseparation capability of the presented CLE-CEC system was significantly enhanced. Eight D,L-AAs were completely separated and three pairs were partially separated under the optimal conditions. The prepared PDA/L-Arg@capillary showed good repeatability and stability. The potential mechanism of the greatly enhanced enantioseparation performance obtained by PDA/L-Arg@capillary was also explored. Moreover, the proposed method was further utilized for studying the enzyme kinetics of L-glutamic dehydrogenase, exhibiting its promising prospects in enzyme assays and other related applications.     

沉淀法高效制备聚多巴胺纳米粒子

为得到分散性和稳定性较好的聚多巴胺纳米粒子,利用“沉淀-再分散法”高效制备了聚多巴胺纳米粒子水分散液。 首先利用溶液氧化法制备了分散在水/乙醇中的聚多巴胺纳米粒子,然后向分散液中加入丙酮使聚多巴胺纳米粒子絮凝。 收集沉降物,用丙酮冲洗并干燥后,加水重新分散得到纯化的聚多巴胺纳米粒子水分散液。 丙酮沉淀法得到的聚多巴胺纳米粒子形貌规整,分散性好,粒径分布在250 nm左右,在水中具有良好的储存稳定性和光热性能,与传统的超速离心提纯法相比,产率可提高57.4%。 此方法为其之后在药物载体及光热治疗等方面的应用研究提供了便利。     

基于聚多巴胺的氮掺杂碳材料的制备及其电化学性能

多孔碳材料由于高的比表面积、优异的电子传导率、良好的化学稳定性等优点在超级电容器电极材料领域被广泛研究。 碳材料的组成及表面孔结构直接影响其电化学性能,为进一步提高碳材料的电容性能,本文首次以聚多巴胺球为前体,KOH为活化剂,通过高温碳化成功制备了良好电化学性能的氮掺杂多孔碳材料。 通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)、 X射线粉末衍射(XRD)、傅里叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)和Raman光谱等对所制备的氮掺杂多孔碳材料进行了形貌及结构组成的表征。 在6 mol/L KOH电解液中, 采用循环伏安、恒电流充放电对多孔碳材料的电化学性能进行了研究。 结果表明,由于双电层电容和赝电容的协同作用,在电流密度为1 A/g时,材料的比电容可达269 F/g,充放电循环1000圈后电容仍可保留初始值的93.5%。