Micro & Nano Letters最新文献

In the current study, a novel method was used to synthesize silver nanoparticles (AgNPs) by utilizing Quercus baloot aqueous extract as a reducing agent. The biosynthesized AgNPs were then subjected to various physicochemical characterizations to assess their effectiveness against microbial familiarity. The characterization techniques included ultraviolet-visible spectro-photometry (UV-Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometer (XRD), and Fourier-transform infrared spectroscopy (FTIR). The UV-Vis analysis revealed a distinctive spectral peak at 420 nm, indicating the presence of silver nanoparticles. SEM imaging displayed the nanoparticle size range of about 100 nm at a magnification of 30,000x, while TEM demonstrated that the nanoparticles had a spherical morphology with a size of approximately 100 nm. Moreover, the crystalline structure of the silver nanoparticles was confirmed by XRD analysis, further validating their successful synthesis. Additionally, FTIR analysis provided evidence of the presence of phytochemicals involved in synthesizing the AgNPs. the biosynthesized silver nanoparticles (AgNPs) were evaluated for antibacterial and antifungal activities. The AgNPs displayed substantial efficacy against common bacterial strains, including Staphylococcus aureus (71%), Escherichia coli (59%), and Klebsiella pneumoniae (64%). Furthermore, they demonstrated significant antifungal activity against plant pathogenic fungi, namely Aspergillus niger (65%), Aspergillus flavus (70%) and Fusarium oxysporum (61%).

The synthesis of pure phase Cu₃SnS₄ is of great significance for improving its material properties. Here, the control law of Cu and Sn element ratio on the synthesis of pure phase Cu₃SnS₄ from physical and chemical methods was analyzed through literature research. The results: (1) the adjustment of the Cu-to-Sn ratio metal elements as a phase control parameter has the characteristics of flexibility and controllability. (2) When the precursor component is rich in Cu and the chemical potential of the medium and high sulphur is high, the phase will develop to a wider thermodynamically stable region of Cu₃SnS₄. By adjusting the Cu-to-Sn ratio elements, when the release rate of anions and the reaction rate of cations adapt to each other, the thermodynamic reaction conditions can be well satisfied, which is beneficial to the preparation of pure phase Cu₃SnS₄. (3) The phase control method of Cu and Sn element ratio of template seed crystal can not only realize the reasonable regulation of Cu and Sn element ratio but also control the synthesis of phase more accurately. The results of this paper have certain reference values for the application of new materials synthesized by adjusting the proportion of elements.

Antibiotic resistance is one of the biggest public health problems of our time. The nanoparticles are a powerful alternative to these antibiotics. Engineered nanoparticles show toxic effects on bacteria by different mechanisms. The bacteria–cell interaction of engineered nanoparticles exerts their toxic effects through changes in cell wall, cell membrane, and cytoplasm content/density. Thus, death occurs as a result of cell deformation. In this study, the cellular damage of silver nanoparticles, which are known to have strong antibacterial properties, and zirconium oxide and silicon oxide engineering nanoparticles, which are less known, on periodontopathic (Prevotella intermedia and Aggregatibacter actinomycetemcomitans) bacteria, were investigated by ultrastructural changes. The lysis of the cytoplasm and separation of the membrane cytoplasm were observed. Both types of bacteria treated with Ag ENP show more hollow cytoplasm than bacteria treated with the other two nanoparticles.

Staphylococcus aureus is the most common cause of wound infections. Infected wounds increase wound severity and have a slower rate of healing. Moreover, emergence of multiple-drug resistant bacteria such as methicillin-resistant S. aureus (MRSA) limited treatment options. This study was therefore aimed to evaluate antibacterial activity against wound pathogen and wound-healing properties of green synthesized ZnO nanoparticles derived from mangosteen peel crude extract (ZnO-Gm). Moreover, their anti-skin cancer activity was also investigated in vitro. As a result, the ZnO-Gm particles significantly inhibited growth of S. aureus and MRSA with the IC₅₀ values at 0.44 and 0.51 mg/mL, respectively. By performing quantitative reactive oxygen species (ROS) assay, the intracellular ROS in both treated S. aureus and MRSA with ZnO-Gm was found to be significantly elevated. Furthermore, ZnO-Gm exhibited cytotoxic effects via induction of apoptosis on the A375 melanoma cancer cell line, with an IC₅₀ value of 8.91 µg/mL, while not affecting the normal cell line (Vero). In addition, 30 µg/mL of ZnO-Gm could strongly promote wound healing of an epidermal keratinocyte cell line (HaCaT). Consequently, the findings of this study demonstrated that the green synthesized ZnO nanoparticles have potential as antibacterial agents, wound-healing materials, and anti-melanoma agents.

Various stamp materials can significantly affect the filling quality of nanoimprint lithography (NIL). The effects of different stamp materials on the imprinting process were investigated from the angles of residual layer (RL) thickness, contact pressure, and filling proportion. The selection of various stamp materials affects the thickness and uniformity of the RL. Soft stamps (PDMS, PU) leave a thin but uneven RL distribution, while the RL imprinted by hard stamps (Si, Ni) is thicker but more uniform. The contact pressure using soft stamps is relatively more evenly distributed than hard stamps. The uneven distribution of contact pressure leads to poor cavity-filling proportion, especially for hard stamps. This study offers guidance for choosing proper nanoimprint stamp materials for different NIL applications.

Lactoferrin (Lf) is an oral-pharmaceutical protein with a variety of biological activities that have attracted the attention of scientists today. In this study, Lf was nano-encapsulated in chitosan biopolymer by ion gelation method with a concentration of 2.5 mg/ml of chitosan and 0.2 and 0.5 mg/ml of Lf and some physicochemical properties were evaluated using zeta potential, DLS, AFM, and SEM. Also, its stability against digestive enzymes such as pepsin and trypsin and its antibacterial effect compare to Lf on Escherichia coli were investigated. The result showed that the mean size of nano-encapsulated lactoferrin (NE-Lf) was 129.6 and 654.6 nm as well as zeta potential, +3.6 and −2.3 mV for 0.2 and 0.5 mg/ml Lf, respectively. SEM and AFM image analysis of NE-Lf showed uniform surfaces, cubic, and homogeneous in shape, as well asdispersion stability of the nanoparticles. NE-Lf had greater stability against the digestion of pepsin and trypsin than Lf. The efficiency of Lf encapsulation in chitosan was 75%. Both NE-Lf and Lf showed that they were able to reduce the growth of E. coli in a dose-dependent manner. EN-Lf was prepared in a simpler way and in lower concentrations of chitosan and Lf than previous methods.