Adverse Effects of Inherent CaO in Coconut Shell-Derived Activated Carbon on Its Performance during Flue Gas Desulfurization.

Activated carbon has been used commercially to remove SO2 from coal combustion flue gas. However, the role of inherent CaO in activated carbon is uncertain. In this study, the adverse effects of inherent CaO in the activated carbon derived from coconut shell (CSAC) on its desulfurization performance were systematically studied at the temperature range of 60-100 °C in a fixed-bed reactor. The solid sorbent samples were analyzed using scanning electron microscopy, X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The flue gas compositions were analyzed by using an online flue gas analyzer. The experimental results showed that the inherent CaO had a profoundly adverse influence on the desulfurization capacity and efficiency of CSAC at all of the temperatures studied. This adverse influence was clearly identified by a comparison of the desulfurization performance of the raw CSAC to those of the acid-washed CSAC samples. It was found that the removal of the inherent CaO from CSAC using a pretreatment of HCl aqueous solution led to an increase in the desulfurization capacity of 41.7%. The adverse effects were attributed to the conversion of CaO into dihydrate calcium sulfate whiskers which formed solid crystals that blocked the micropores of the CSAC particles.

De Novo Design of Skin-Penetrating Peptides for Enhanced Transdermal Delivery of Peptide Drugs.

Skin-penetrating peptides (SPPs) are attracting increasing attention as a non-invasive strategy for transdermal delivery of therapeutics. The identification of SPP sequences, however, currently performed by experimental screening of peptide libraries, is very laborious. Recent studies have shown that, to be effective enhancers, SPPs must possess affinity for both skin keratin and the drug of interest. We therefore developed a computational process for generating and screening virtual libraries of disulfide-cyclic peptides against keratin and cyclosporine A (CsA) to identify SPPs capable of enhancing transdermal CsA delivery. The selected sequences were experimentally tested and found to bind both CsA and keratin, as determined by mass spectrometry and affinity chromatography, and enhance transdermal permeation of CsA. Four heptameric sequences that emerged as leading candidates (ACSATLQHSCG, ACSLTVNWNCG, ACTSTGRNACG, and ACSASTNHNCG) were tested and yielded CsA permeation on par with previously identified SPP SPACE (TM) . An octameric peptide (ACNAHQARSTCG) yielded significantly higher delivery of CsA compared to heptameric SPPs. The safety profile of the selected sequences was also validated by incubation with skin keratinocytes. This method thus represents an effective procedure for the de novo design of skin-penetrating peptides for the delivery of desired therapeutic or cosmetic agents.

Synthesis and characterization of a self-fluorescent hyaluronic acid-based gel for dermal applications.

Combinations of polymer conjugates affording in situ gelation hold promise for treatment of pathological cavities (e.g., arthritis) and sustained drug release. In particular, hyaluronic acid (HA) functionalized with reactive groups is regarded as an excellent biomaterial due to its tunable cross-linking kinetics and mechanical properties. HA-based reagents, however, can be irritating to surrounding tissues due to the reactivity of pendant groups, and their fast gelation kinetics can result in poor cavity filling. In this study, a biocompatible "click" reaction between cyanobenzothiazole (CBT) and d-cysteine (d-Cys) is employed to produce HA-based conjugates for in situ gelation. Rheological studies conducted on a gel obtained from the combination of HA-CBT and HA-d-Cys indicate optimal gelation time and mechanical properties. Further, in vitro studies on porcine skin demonstrate the ability of the gel to form in situ upon subcutaneous injection or topical application, and to act as a reservoir for sustained release of protein therapeutics. Finally, the safety of the HA-based conjugates is demonstrated on human keratinocytes. The presented results demonstrate the applicability of the binary mixture for in situ gelation and the potential of the proposed system for a variety of biomedical applications.