Rojrit Rojanathanes

A novel series of Zn-II-trans-A(2)B(2) porphyrins and benzoporphyrins bearing phenyl and thiophene-based meso-substituents was successfully synthesized and characterized by spectroscopic and electrochemical techniques. Systematic comparison among the compounds in this series, together with the corresponding A(4) analogs previously studied by our group, led to the understanding of the effects of pi-conjugated system extension of a porphyrin core through beta-fused rings, replacement of the phenyl with the thiophene-based meso-groups, and introduction of additional thiophene rings on thienyl substituents on photophysical and electrochemical properties. Oxidative electropolymerization through bithiophenyl units of both A(4) and trans-A(2)B(2) analogs was achieved, resulting in porphyrin- and benzoporphyrin-oligothiophene conjugated polymers, which were characterized by cyclic voltammetry and absorption spectrophotometry. Preliminary studies on catalytic performance toward electrochemical reduction of carbon dioxide (CO2) was described herein to demonstrate the potential of the selected compounds for serving as homogeneous and heterogeneous electrocatalysts for the conversion of CO2 to carbon monoxide (CO).

Twelve derivatives of biguanide-derived 1,3,5-triazines, a promising class of anticancer agent, were synthesised and evaluated for their anticancer activity against two colorectal cancer cell lines—HCT116 and SW620. 2c and 3c which are the derivatives containing o-hydroxyphenyl substituents exhibited the highest activity with IC₅₀ against both cell lines in the range of 20–27 µM, which is comparable to the IC₅₀ of cisplatin reference. Moreover, the potential use of the calcium citrate nanoparticles (CaCit NPs) as a platform for drug delivery system was studied on a selected 1,3,5-triazine derivative 2a. Condition optimisation revealed that the source of citrate ions and reaction time significantly influence the morphology, size and %drug loading of the particles. With the optimised conditions, “CaCit-2a NPs” were successfully synthesised with the size of 148 ± 23 nm and %drug loading of up to 16.3%. Furthermore, it was found that the release of 2a from the synthesised CaCit-2a NPs is pH-responsive, and 2a could be control released under the acidic cancer environment. The knowledge from this study is perceptive for further development of the 1,3,5-triazine-based anticancer drugs and provide the platform for the incorporation of other drugs in the CaCit NPs in the future.

Leptospira infection can cause potential hazards to human health by stimulating inflammation, which is mediated mainly through the Toll-like receptor 2 (TLR2) pathway. Gold nanoparticles (AuNPs) are promising for medical applications, as they display both bioinert and noncytotoxic characteristics. AuNPs have been shown to have the ability to modify immune responses. To understand the in vitro immunomodulatory effect of AuNPs in a Leptospira infection model, the activation of TLR2 expression was examined in HEK-Blue-hTLR2 cells treated with Leptospira serovars and/or AuNPs (10 and 20 nm). The ability of AuNPs to modulate an inflammatory response induced by Leptospira was examined in terms of transcript expression level modulation of three proinflammatory cytokines (tumor necrosis factor-α, interleukin (IL)-1β and IL-6) using two-stage quantitative real-time reverse transcriptase PCR. The results revealed that the administration of 10 nm AuNPs could augment the Leptospira-induced TLR2 signaling response and upregulate the expression of all three cytokine gene transcripts, whereas the 20 nm AuNPs attenuated the TLR2 activation and expression of proinflammatory cytokines. This indicates that AuNPs can modulate inflammatory parameters in Leptospira infection and different-sized AuNPs had different immunomodulatory functions in this model.

In this work, the preparation of novel calcium citrate (CaCit) nanoparticles (NPs) has been disclosed and the use of these NPs as “Trojan” carriers has been demonstrated. The concentration ratio between calcium ions and citrate ions was optimized, yielding spherical NPs with size in the range of 100–200 nm. Additionally, a fluorescent dye, fluorescein isothiocyanate (FITC), was successfully encapsulated by the coprecipitation method. The products were characterized by thermogravimetric analysis and scanning electron microscopy. The cellular uptake was investigated by incubating the synthesized fluorescent-tagged NPs with human keratinocytes using a confocal microscope. The accumulation of the FITC in the cells suggested that the CaCit NPs can potentially be used as novel drug carriers.