Perovskite Nanowire Laser for Hydrogen Chloride Gas Sensing.

Detection of hazardous volatile organic and inorganic species is a crucial task for addressing human safety in the chemical industry. Among these species, there are hydrogen halides (HX, X = Cl, Br, I) vastly exploited in numerous technological processes. Therefore, the development of a cost-effective, highly sensitive detector selective to any HX gas is of particular interest. Herein, we demonstrate the optical detection of hydrogen chloride gas with solution-processed halide perovskite nanowire lasers grown on a nanostructured alumina substrate. An anion exchange reaction between a CsPbBr3 nanowire and vaporized HCl molecules results in the formation of a structure consisting of a bromide core and thin mixed-halide CsPb(Cl,Br)3 shell. The shell has a lower refractive index than the core does. Therefore, the formation and further expansion of the shell reduce the field confinement for experimentally observed laser modes and provokes an increase in their frequency. This phenomenon is confirmed by the coherency of the data derived from XPS spectroscopy, EDX analysis, in situ XRD experiments, HRTEM images, and fluorescent microspectroscopy, as well as numerical modeling for Cl- ion diffusion and the shell-thickness-dependent spectral position of eigenmodes in a core-shell perovskite nanowire. The revealed optical response allows the detection of HCl molecules in the 5-500 ppm range. The observed spectral tunability of the perovskite nanowire lasers can be employed not only for sensing but also for their precise spectral tuning.

Minimal PK/PD model for simultaneous description of the maximal tolerated dose and metronomic treatment outcomes in mouse tumor models.

PURPOSE: Metronomic chemotherapy (MC) is a promising approach where, in contrast to the conventional maximal tolerated dose (MTD) strategy, regular fractionated doses of the drug are used. This approach has proven its efficacy, although drug dosing and scheduling are often chosen empirically. Pharmacokinetic/pharmacodynamic (PK/PD) models provide a way to choose optimal protocols with computational methods. Existing models are usually too complicated and are valid for only a subset of drug schedules. To address this issue, we propose herein a simple model that can describe MC and MTD regimens simultaneously. METHODS: The minimal model comprises tumor suppression due to antiangiogenic drug effect together with a cell-kill term, responsible for its cytotoxicity. The model was tested on data obtained on tumor-bearing mice treated with gemcitabine in ether MTD, MC, or combined (MTD + MC) regimens. RESULTS: We conducted a number of tests in which data were divided in various ways into training and validation sets. The model successfully described different trends in the MTD and MC regimens. With parameters obtained by fitting the model to MTD data, the simulations correctly predicted trends in both the MC and combined therapy groups. CONCLUSION: Our results demonstrate that the proposed model presents a minimal yet efficient tool for modeling outcomes in different treatment regimens in mice. We hope that this model has the potential for use in clinical practice in the development of patient-specific chemotherapy scheduling protocols based on observed treatment response.

Linking sequence patterns and functionality of alpha-helical antimicrobial peptides.

MOTIVATION: The rational design of antimicrobial peptides (AMPs) with increased therapeutic potential requires deep understanding of the determinants of their activities. Inspired by the computational linguistic approach, we hypothesized that sequence patterns may encode the functional features of AMPs. RESULTS: We found that α-helical and ß-sheet peptides have non-intersecting pattern sets and therefore constructed new sequence templates using only helical patterns. Designed peptides adopted an α-helical conformation upon binding to lipids, confirming that the method captures structural and biophysical properties. In the antimicrobial assay, 5 of 7 designed peptides exhibited activity against Gram(+) and Gram(-) bacteria, with most potent candidate comparable to best natural peptides. We thus conclude that sequence patterns comprise the structural and functional features of α-helical AMPs and guide their efficient design. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.