Antibacterial activities of physiologically stable, self-assembled peptide nanoparticles.

In this study, we report that host defense protein-derived ten amino acid long disulfide-linked peptides self-assemble in the form of ß-sheets and ß-turns, and exhibit concentration-dependent self-assembly in the form of nanospheres, termed as disulfide linked nanospheres (DSNs). As expected, bare DSNs are prone to aggregation in ionic solutions and in the presence of serum proteins. To yield physiologically stable self-assembled peptide-based materials, DSNs are stabilized in the form of supramolecular assemblies using ß-cyclodextrins (ß-CD) and fucoidan, as delivery carriers. The inclusion complexes of DSNs with ß-CD (ß-CD-DSN) and electrostatic complexation of fucoidan with DSNs (FC-DSN) stabilizes the secondary structure of DSNs. Comparison of ß-CD-DSNs with FC-DSNs reveals that inclusion complexes of DSNs formed in the presence of ß-CD are highly stable under physiological conditions, show high cellular uptake, exhibit bacterial flocculation, and enhance antibacterial efficacies of DSNs in a range of Gram-positive and Gram-negative bacteria.

Quantification of landfill gas generation and renewable energy potential in arid countries: Case study of Bahrain.

Sustainable solid waste management can provide pathways for renewable energy generation. The Kingdom of Bahrain has witnessed burgeoning municipal solid waste (MSW) generation rate due to socio-economic development. The authorities of this Small Island Developing State, which is located in arid environment, plan to produce 5% of the total electricity demand from renewable energy sources by 2025 and then double it to 10% by 2035. The US Environmental Protection Agency's Landfill Gas Emission Model software was used to estimate the generation of biogas from MSW at the Askar Landfill site. Results envisaged that maximum landfill gas (LFG) emission rates will be in 2020 following landfill closure by the end of 2019, as an intentional scenario, with a maximum electricity generation potential of 57.4 GWh that could provide power to 488 households. Revenues from carbon credits and electricity sales were US$97.8 million and US$64.8 million, respectively, for the period 2020-2035. The internal combustion engine exhibited the most viable option based on economic analysis of the cost of alternative LFG energy recovery technologies. Our work highlights the potential to use LFG-to-energy technologies to reduce the carbon footprint in arid climates for developing countries with substantial electricity subsidization.

Diatoms embedded, self-assembled carriers for dual delivery of chemotherapeutics in cancer cell lines.

The concept of dual drug delivery to treat relapsing tumors is a well-studied approach to improve the antitumor efficacies and to reduce the side effects of single drug chemotherapeutic treatments. One of the major issues with dual drug delivery to treat drug resistant tumors is the concentration and ratio dependent antagonistic behavior of two drugs, which may reverse the anticancer efficacies of individual chemotherapeutics and stimulate the growth of tumor cells. In this paper, we address this issue by developing diatomaceous earth embedded core shell materials, which are capable of encapsulating two chemotherapeutic drugs at constant molar ratios, in different compartments of a single drug delivery carrier. The encapsulation of each drug in different compartments of delivery carrier (core of diatoms versus shell of cyclodextrin) then controls the release rate of both drugs in situ, and maintains the optimal molar ratios required for their synergistic outcomes in vitro.