Nanolattice-Forming Hybrid Collagens in Protective Shark Egg Cases.

Nanoscopic structural control with long-range ordering remains a profound challenge in nanomaterial fabrication. The nanoarchitectured egg cases of elasmobranchs rely on a hierarchically ordered latticework for their protective function─serving as an exemplary system for nanoscale self-assembly. Although the proteinaceous precursors are known to undergo intermediate liquid crystalline phase transitions before being structurally arrested in the final nanolattice architecture, their sequences have so far remained unknown. By leveraging RNA-seq and proteomic techniques, we identified a cohort of nanolattice-forming proteins comprising a collagenous midblock flanked by domains typically associated with innate immunity and network-forming collagens. Structurally homologous proteins were found in the genomes of other egg-case-producing cartilaginous fishes, suggesting a conserved molecular self-assembly strategy. The identity and stabilizing role of cross-links were subsequently elucidated using mass spectrometry and in situ small-angle X-ray scattering. Our findings provide a new design approach for protein-based liquid crystalline elastomers and the self-assembly of nanolattices.

Response surface method for polyhydroxybutyrate (PHB) bioplastic accumulation in Bacillus drentensis BP17 using pineapple peel.

Polyhydroxybutyrate (PHB) is a biodegradable biopolymer which is useful for various applications including packing, medical and coating materials. An endospore-forming bacterium (strain BP17) was isolated from composted soil and evaluated for PHB production. Strain BP17, taxonomically identified as Bacillus drentensis, showed enhanced PHB accumulation and was selected for further studies. To achieve maximum PHB production, the culture conditions for B. drentensis BP17 were optimized through response surface methodology (RSM) employing central composite rotatable design (CCRD). The final optimum fermentation conditions included: pineapple peel solution, 11.5% (v/v); tryptic soy broth (TSB), 60 g/L; pH, 6.0; inoculum size, 10% (v/v) and temperature, 28°C for 36 h. This optimization yielded 5.55 g/L of PHB compared to the non-optimized condition (0.17 g/L). PHB accumulated by B. drentensis BP17 had a polydispersity value of 1.59 and an average molecular weight of 1.15x105 Da. Thermal analyses revealed that PHB existed as a thermally stable semi-crystalline polymer, exhibiting a thermal degradation temperature of 228°C, a melting temperature of 172°C and an apparent melting enthalpy of fusion of 83.69 J/g. It is evident that B. drentensis strain BP17 is a promising bacterium candidate for PHB production using agricultural waste, such as pineapple peel as a low-cost alternative carbon source for PHB production.

Potential of levitated drops to serve as microreactors for biophysical measurements.

Microreactors are desirable for exploring chemical and biological processes, as reactant consumption is minimal and safety issues are easily managed. Levitated drops are a class of microreactors for which mixing is continuous and solid/liquid interfaces are absent or of lesser importance than in channeled microfabricated flow reactors. Thus, reactant adsorption or wall catalysis possibly of importance in ordinary microfluidic systems is absent in levitated drops. Transport of gaseous reactants or products is facile. Levitated drop microreactors are amenable to batch or continuous flow study of biochemical reactions. The possibility of studying oscillatory enzyme-catalyzed reactions in drops is apparent. This review explains the physics and chemistry of levitated drop microreactors and describes practical aspects of their design, fabrication, implementation, and optimization. Such considerations as drop evaporation, thermal control, protein behavior at the gas/liquid interface, and observation with spectroscopic and electrochemical probes are discussed.