化学最新文献

Microplastics are becoming increasingly abundant waste products; therefore, the risk of human exposure is also increasing. The cytotoxic consequences of microplastic exposure, particularly in cancer, have yet to be explored. We obtained commercially available polystyrene nanoparticles of uniform size (86.61 ± 6.41 nm) and confirmed the chemical composition and shape using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), respectively. We evaluated colloidal stability over a range of concentrations from 1-1000 µg mL^-1 using hydrodynamic diameter and zeta potential, determining that higher concentrations exhibit greater colloidal stability compared to lower concentrations. Specifically, the zeta potential increased from very negative values of approximately -40 mV to approximately zero mV. To evaluate the cytotoxic effects of these microplastics, we evaluated the relative cell viability in vitro of HeLa cervical cancer cells, including those with DNA damage repair deficiencies in MLH1 and MSH2. High concentrations of polystyrene were required for observable decreases in cell viability, particularly in esterase activity measured with calcein AM. Cellular internalization of the nanoparticles was confirmed quantitatively using intracellular fluorescence and qualitatively using confocal microscopy for fluorescent polystyrene. Overall, these results indicate that high concentrations of polystyrene are required to elicit toxicological effects in cervical cells within 24 hours.

Molecular self-assembly creates complex structures through noncovalent interactions. Synthetic fuel-driven systems mimic biology, yet the effects of subtle design changes, particularly hydrophobic groups such as alkyl chains, are still not well understood. This study showed that the alkyl chain length critically influences the dynamic assembly of short peptides. Z-capped peptides C3 and C6, composed of l-phenylalanine and -glutamic acid, with L-aspartic acid as the reactive site and alkylamide groups of varying lengths at the C-terminus, have been observed to form metastable aggregates via intramolecular anhydride formation during a chemically fueled reaction cycle. We elucidated that the difference in alkyl chain length resulted in either highly dynamic assemblies or delayed structural dissolution. Our findings provide a comprehensive understanding of these observations, illustrating how rational peptide design enable precise control over nanostructure properties and catalytic lifetimes.

Elastin-like polypeptides (ELPs) are a family of recombinant biopolymers that offer precise sequence control. Six ELP sequences with systematically varied hydrophobicity and charge were designed to investigate how hydrophobicity and charge influence dilute solution phase behavior in 0-40 mol % ethanol and 0-200 mM sodium chloride. Both hydrophobic and hydrophilic ELPs in this study display four characteristic regimes in their phase diagrams: lower critical solution temperature (LCST)-like transitions at low ethanol concentrations, a one-phase region at low-to-moderate ethanol concentrations, upper critical solution temperature (UCST)-like transitions at intermediate ethanol concentrations, and full miscibility at high ethanol concentrations. Despite an identical overall composition with a previously studied ELP sequence, differences in sequence and molecular weight significantly impact phase behavior in ethanol/water mixtures. These results reveal both sequence dependence in the phase behavior of ELPs and universal cononsolvency behavior in uncharged hydrophobic and hydrophilic ELPs.

Androgenetic alopecia (AGA) is the most common type of hair loss. Its successful treatment depends on effective transdermal drug delivery strategies. In this study, we introduce a novel method utilizing a controlled rigidity nanolipogel (NLG) for the local delivery of fucosterol in the treatment of AGA. The NLG is formed by an identical lipid bilayer encapsulating an alginate core, with rigidity regulated by the degree of sodium alginate (SA) cross-linking. Young's moduli obtained by AFM were 2.91 ± 0.41, 61.5 ± 1.6, and 84.9 ± 1.1 MPa for the soft NLP, moderately rigid NLG-2.5, and most rigid NLG-10. In vitro skin permeation study showed that compared with the NLP and NLG-10, NLG-2.5 had the best transdermal permeability and hair follicle-targeting properties. Moreover, moderately rigid NLG-2.5 exhibited the best ability to inhibit inflammation and androgen pathways and promote angiogenesis, thereby restoring hair growth in AGA model mice. This strategy provides valuable insights for the treatment of AGA.