A Facile Method to Synthesize 3D Pomegranate-like Polydopamine Microspheres

Nanospheres have found versatile applications in the biomedical field; however, their possible harmful effects on immune and inflammatory systems are also a crucial concern. Inspired by a pomegranate structure, we demonstrated a novel structure for the nanostructured microspheres to overcome the drawbacks of nanospheres without compromising their merits. In this study, 3D pomegranate-like polydopamine microspheres (PDAMS) were synthesized by self-oxidative polymerization of dopamine hydrochloride. Herein, controlling the pH during polymerization led to synthesizing homogeneous agglomerated nano-sized spheres (400–2000 nm) and finally forming tunable and monodisperse micron-sized particles (21 µm) with uniform spherical shape porous microstructure. PDAMS interaction with the potential targets, Bone morphogenetic protein-2 (BMP2), Decorin, and Matrilin-1, was investigated via molecular calculations. Theoretical energy analysis revealed that PDAMS interaction with BMP2, Decorin, and Matrilin-1 is spontaneous, so that a protein layer formation on the PDAMS surface suggests application in bone and cartilage repair. It was also observed that PDAMS presented in-vitro degradation within 4 weeks. Here, disappearance of the UV-VIS spectrum peak at 280 nm is accompanied by the degradation of catechol groups. Pomegranate-like PDAMS support the biomimetic formation of hydroxyapatite-like layers, making them appropriate candidates for hard tissue applications. Herein, the appearance of peaks in XRD spectrum at 31.37, 39.57, 45.21, and 50.13° attributed to hydroxyapatite-like layers formation. All these results demonstrated that self-oxidative polymerization under a controllable pH can be a green and straightforward technique for preparing the pomegranate-like PDAMS and providing an innovative basis for further pre-clinical and clinical investigations.

Nanoarchitectonics of BN/AgNWs/Epoxy Composites with High Thermal Conductivity and Electrical Insulation

To promote the construction of the thermal network in the epoxy resin (EP), a certain proportion of silver nanowires (AgNWs) coupled with the hexagonal boron nitride (BN) nanoplates were chosen as fillers to improve the thermal conductivity of EP resin. Before preparing the composites, BN was treated by silane coupling agent 3-aminopropyltriethoxysilane (KH550), and AgNWs was coated by dopamine hydrochloride. The BN/AgNWs/EP composites were prepared after curing, and the thermal conductivity and dielectric properties of the composites was tested. Results showed that the AgNWs and BN were uniformly dispersed in epoxy resin. It synergistically built a thermal network and greatly increased the thermal conductivity of the composites, which increased 9% after adding AgNWs. Moreover, the electrical property test showed that the addition of AgNWs had little effect on the dielectric constant and dielectric loss of the composites, indicating a rather good electrical insulation of the composites.

Impact of Biogenic Amines on the Growth of Green Microalgae

Background: The goal of this research project was to test various neuroactive amines in the capacity of growth stimulators/accelerators of the green microalgae Scenedesmus quadricauda and Chlorella vulgaris that have much biotechnological potential because they can be used for producing drugs, food ingredients, cosmetics, and biofuel. The issue of the ecological role of the biogenic amines in terms of interspecies communication in aqueous ecosystems was also addressed in this work. Methods: S. quadricauda strain GEHD and C. vulgaris strain ALP were cultivated in the light with constant aeration at 24oC in a minerals-containing medium. Experimental systems contained 1, 10 or 100 mM of dopamine hydrochloride, histamine hydrochloride, norepinephrine hydrochloride, or serotonin hydrochloride that were added at inoculation as freshly prepared aqueous solutions. Algal cells were counted using a light microscope , and their number in 1 mL of culture was calculated. The culture liquid and sonicated biomass of S. quadricauda and C. vulgaris were tested for the presence of endogenous amines using high-performance liquid chromatography (HPLC) with an amperometric detector. Results: The biogenic amines serotonin, norepinephrine, dopamine, and histamine significantly stimulated the growth of S. quadricauda, at concentrations of 1 and/or 10 mM but not 100 mM. Histamine was the most efficient stimulator, causing an average 65% increase in biomass accumulation at the end of the cultivation period. The effects of serotonin, dopamine and histamine on C. vulgaris were reported in our previous publication [1], but this work contains the results of our experiments with the previously untested norepinephrine that slightly stimulated the growth of C. vulgaris. HPLC analysis failed to reveal any endogenous amines in the culture liquid and biomass of both microalgae. Conclusions: Since biogenic amines stimulate the growth of the microalgae S. quadricauda and C. vulgaris but are not synthesized by them, we suggest that the algae normally respond to amines produced by other components of aqueous ecosystems, including zooplankton and fish that are known to release significant amounts of biogenic amines into the environment. The data obtained hold some promise with regard to developing a relatively economical technique of boosting algal biomass production.

A Superhydrophobic Moso Bamboo Cellulose Nano-Fibril Film Modified by Dopamine Hydrochloride

The moso bamboo fiber powder was used as raw material to prepare cellulose nano-fibril films, 5% of polyvinyl alcohol solution was used as a structural reinforcement agent, dopamine hydrochloride (DA) was used as a surface adhesive, and hexadecyl trimethoxy silane was used as a surface modifier. The superhydrophobic films were prepared by vacuum filtration and impregnation. The results showed that the water contact angle on the surface of the film could reach 156°. The microstructure and chemical composition of the film surface was further studied by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and roughness measurement The scanning electron microscopy images showed that the nanofibers on the surface of Cellulose nanofibers film were arranged and randomly distributed, thus forming a dense network interwoven structure. In PDA hydrophobic modification solution, an Hexadecyltrimethoxysilane was hydrolyzed to a hexadecyl silanol to obtain the polar terminal hydroxyl of Hexadecyl silanol molecule. The -OCH3 terminal group of HDTMS reacted with hydroxyl/H2O to form a silanol (Si-OH) bond and further condensed to form a Si-O-Si network. In addition, due to the hydrophilicity of the surface of the nano cellulose film, a large amount of—OH was adsorbed on the surface of the nano cellulose film, resulted in the chemical connection between cetyl groups, thus realized the grafting of cetyl long-chain alkyl groups onto the fibers of the nano cellulose film.The film showed good self-cleaning and waterproof properties, which can be widely used in wet environment packaging and building.

Colored Surfaces Made of Synthetic Eumelanin

The polymerization of 3,4-dihydroxy-L-phenylalanine leads to a carboxylic acid-rich synthetic melanin-like material (poly-L-DOPA). Synthetic melanin most resembles natural eumelanin in chemical structure. However, its deposition on surfaces leading to colored surfaces by interference is not as easy to accomplish as in the case of the preparation of colored surfaces by dopamine hydrochloride polymerization. This study deals with the preparation of new colored surfaces made from poly-L-DOPA displaying vivid colors by interference. These surfaces were obtained by depositing thin films of poly-L-DOPA on a reflective silicon nitride substrate. A high ionic strength in the polymerization medium was essential to accomplish the coating. The effect of ionic strength on the resulting surfaces was studied via reflectance, Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The refractive index was determined by ellipsometry, and was nearly constant to 1.8 when λ > 650 nm. In the visible spectral region, the imaginary part of the refractive index becomes relevant. The refractive index in the visible wavelength range (400–600 nm) was in the range 1.7–1.80.