Contact Angle of Nepenthes alata Slippery Zone: Results from Measurement and Model Analysis

The slippery zone of Nepenthes alata depends on its highly evolved morphology and structure to show remarkable superhydrophobicity, which has gradually become a biomimetic prototype for developing superhydrophobic materials. However, the mechanism governing this phenomenon has not been fully revealed through model analysis. In this paper, the superhydrophobicity of slippery zone is studied by contact angle measurement, morphology/structure examination and model analysis. The slippery zone causes ultrapure water droplet to produce a considerably high contact angle (155.11–158.30°), and has a micro-nano scale hierarchical structures consisting of lunate cells and wax coverings. According to the Cassie-Baxter equation and a self-defined infiltration coefficient, a model was established to analyze the effect of structure characteristic on the contact angle. Analysis result showed that the calculated contact angle (154.67–159.49°) was highly consistent with the measured contact angle, indicating that the established model can quantitatively characterize the relationship between the contact angle and the structure characteristic. Our study provides some evidences to further reveal the superhydrophobic mechanism of Nepenthes alata slippery zone, as well as inspires the biomimetic development of superhydrophobic surfaces.

Characterization of the Naked Mole Rat Incisors: Chemical Composition, Microstructure and Mechanical Properties

The naked mole rat incisors (NMRI) exhibit excellent mechanical properties, which makes it a good prototype for design and fabrication of bionic mechanical systems and materials. In this work, we characterized the chemical composition, microstructure and mechanical properties of NMRI, and further compared these properties with the laboratory rat incisors (LRI). We found that (1) Enamel and dentin are composed of organic matter, inorganic matter and water. The ratio of Ca/P in NMRI enamel is higher than that of LRI enamel. (2) The dentin has a porous structure. The enamel has a three-dimensional reticular structure, which is more complex, regular and denser than the lamellar structure of LRI enamel. (3) Enamel has anisotropy. Its longitudinal nano-hardness is greater than that of transverse nano-hardness, and both of them are higher than that of LRI enamel. Their nano-hardness and elastic modulus increase with the increment of distance from the enamel-dentin boundary. The nano-hardness of dentin is smaller than that of enamel. The chemical composition and microstructure are considered to be the reasons for the excellent properties of NMRI. The chemical composition and unique microstructure can provide inspiration and guidelines for the design of bionic machinery and materials.

A Histopathological Evaluation of Amino Acids-Capped Silver Nanoconjugates (AgNCs) Against Cadmium-Induced Toxicity in Albino Mice

Various molecules may modify the surface chemistry of commonly used nanomaterials (NMs), resulting in the synthesis of novel and safer NMs. The current study was delineated to evaluate the in vivo toxicity profiling of the silver nanoconjugates (AgNCs) conjugated with different amino acids. The L-glycine capped-AgNCs exhibited toxicity and caused tissue damage, while L-cystine and L-tyrosine capped-AgNCs showed protective effects against cadmium-induced toxicity. L-cystine-capped-AgNCs performed well as compared to other amino acids-AgNCs. The level of serum creatinine, ALT, AST, ALP, and blood urea increased (p<0.05) in G2, G3, and G5 in comparison to G1 (control group). While an increase in bilirubin for G2 was statistically non-significant (p>0.05). The ALT and AST elevated (p<0.05) in G4, however, other serological parameters in G4 and G6 didn’t show any noticeable change in their values. Histological analysis showed disturbed and deformed cellular structures in liver and kidney tissues of G2, G3, and G5. However, G4 and G6 samples demonstrated minute changes in comparison to G1. It is concluded that L-cystine and L-tyrosine-capped-AgNCs exhibited protective effects and should be tested further for developing safer nanoconjugates for biomedical uses.

Formulation of Nanoemulgel from Extracts of Musa acuminata: In-Vitro Kinetics and Antimicrobial Studies

The study was intended to formulate nanoemulgel from the leaf extract of Musa acuminata. Ethanol and Chloroform were used as solvents in the ratio of 1:8 (%w/v). DL- alpha-Tocopherol, characterized by GCMS, was identified to be the major component with potential biological activities. Based on a pseudo ternary plot, the 1:1 Smix (Surfactant: Co- Surfactant) ratio was optimized as it posed maximum regions of emulsion. The prepared nanoemulgel was evaluated for physical appearance, pH, spreadability, and swelling index. The appearance was pale yellowish-white, translucent within a pH range of 5-5.8. Antimicrobial studies were performed against dandruff-causing microbes (Staphylococcus epidermidis and Malassezia furfur). Invitro studies were carried out for optimized formulations of EG2, EG4, CG2, and CG3. The drug release of 94.28% after 12 h with Higuchi plot of R2 value as 0.99 was observed for EG2. The kinetically optimized formulation, EG2 was found to have good spreadability of 12.2 (g cm) s−1 and a swelling index of 64%.