Ultrasmall Zwitterionic Polypeptide-Coordinated Nanohybrids for Highly Efficient Cancer Photothermal Ferrotherapy.

Ferroptosis therapy (FT) based on the Fenton reaction of ferrous nanoparticles has been becoming a unique strategy for cancer treatment; however, current ferrous nanoparticles suffer from slower Fenton reaction kinetics, lower ferroptosis efficacy, and long-term toxicity, so it is urgent to construct biocompatible ferrous nanomaterials with highly efficient Fenton reaction activity for cancer FT. Inspired by single-atom catalysis and size-determined tumor penetration, we conceived an innovative strategy for constructing ultrasmall zwitterionic polypeptide-coordinated nanohybrids of PCGA@FeNP with about 6 nm by utilizing thiol/hydroxyl-iron cooperative coordination chemistry. The ultrasmall size, unsaturated ferrous coordination, and intracellular acidic pH could accelerate the Fenton reaction, thus boosting the efficacy of ferroptosis. Moreover, those coordinated nanohybrids exhibited prominent photothermia with 59.5% conversion efficiency, further accelerating the Fenton reaction and inducing a synergistic effect between FT and photothermal therapy (PTT). In vitro and in vivo GPX-4 expression ascertained that PCGA@FeNP indeed induced effective FT and synergistic FT-PTT. Remarkably, in vivo FT-PTT completely ablated 4T1 solid tumors by one treatment, presenting outstanding and synergistic antitumor efficacy via the photothermia-boosted ferroptosis and apoptosis pathways. This work supplies a practicable strategy to fabricate ultrasmall zwitterionic coordination nanohybrids for highly efficient cancer FT and FT-PTT theranostics with potential clinical transitions.

UV-C irradiated gallic acid exhibits enhanced antimicrobial activity via generation of reactive oxidative species and quinone.

A novel light-enhanced antimicrobial treatment was developed by exposing gallic acid (GA) to UV-C light. GA (15 mM) solution was exposed to UV-C for 30 min and subsequently incubated with E. coli O157:H7 for 30 min to achieve a 3.2 ±â€¯0.2 log CFU/mL reduction. The antimicrobial activity is affected by the irradiation duration, wavelength, and pH of solution. The addition of benzenesulfinic acid (BSA) to UV-C irradiated GA lowered (P < 0.05) its antimicrobial activity, indicating that quinones contributed to its overall antimicrobial effect. In addition, the attenuated (P < 0.05) antimicrobial activity of UV-C exposed GA in the presence of reactive oxidative species (ROS) quenchers, the generation of hydrogen peroxide, and increased levels of intracellular oxidative stress detected in E. coli O157:H7 illustrated that ROS also played a role in the antimicrobial effect of UV-C irradiated GA. UV-C irradiated GA could be applied as a novel antimicrobial in food systems.

Photodegradation of gallic acid under UV irradiation: insights regarding the pH effect on direct photolysis and the ROS oxidation-sensitized process of DOM.

In this study, the degradation of gallic acid (GA), a model compound for dissolved organic matter (DOM) in controlled UV/N2, UV/air, UV/Fe(3+)/N2, and UV/Fe(3+)/air systems was investigated to elucidate the contribution of direct photolysis and reactive oxygen species (ROS) oxidation to GA degradation at various pH values. In general, the order of the degradation rate of GA in these four systems was as follows: UV/Fe(3+)/air>UV/air>UV/Fe(3+)/N2≈UV/N2. In the UV/N2 system, GA underwent slow direct photolysis, the rate of which decreased with decreasing pH. In the UV/Fe(3+)/air system, the most rapid GA degradation was achieved at pH 5. ROS are mainly derived from two sources. The first source is attributed to the role of DO and the other is attributed to the interaction of Fe(3+) and DO. The contribution of ROS to GA oxidation is much greater (>71%) than that of direct photolysis (<29%) at each pH value and is most obvious at pH 5. H2O2 formation was detected during GA degradation in the UV/air and UV/Fe(3+)/air systems. Using ROS scavengers, it was found that oxidation by OH was the main mechanism of GA degradation in the UV/Fe(3+)/air system. Based on the experimental results, a mechanism for GA degradation and ROS formation involving the effect of pH was proposed. This study furthers our understanding of changes in DOM degradation mechanisms due to global acidification.

Phragmites australis root secreted phytotoxin undergoes photo-degradation to execute severe phytotoxicity.

Our study organism, Phragmites australis (common reed), is a unique invader in that both native and introduced lineages are found coexisting in North America. This allows one to make direct assessments of physiological differences between these different subspecies and examine how this relates to invasiveness. Recent efforts to understand plant invasive behavior show that some invasive plants secrete a phytotoxin to ward-off encroachment by neighboring plants (allelopathy) and thus provide the invaders with a competitive edge in a given habitat. Here we show that a varying climatic factor like ultraviolet (UV) light leads to photo-degradation of secreted phytotoxin (gallic acid) in P. australis rhizosphere inducing higher mortality of susceptible seedlings. The photo-degraded product of gallic acid (hereafter GA), identified as mesoxalic acid (hereafter MOA), triggered a similar cell death cascade in susceptible seedlings as observed previously with GA. Further, we detected the biological concentrations of MOA in the natural stands of exotic and native P. australis. Our studies also show that the UV degradation of GA is facilitated at an alkaline pH, suggesting that the natural habitat of P. australis may facilitate the photo-degradation of GA. The study highlights the persistence of the photo-degraded phytotoxin in the P. australis's rhizosphere and its inhibitory effects against the native plants.

Radiolytic degradation of gallic acid and its derivatives in aqueous solution.

Polyphenols, like gallic acid (GA) released in the environment in larger amount, by inducing some unwanted oxidations, may constitute environmental hazard: their concentration in wastewater should be controlled. Radiolytic degradation of GA was investigated by pulse radiolysis and final product techniques in dilute aqueous solution. Subsidiary measurements were made with 3,4,5-trimethoxybenzoic acid (TMBA) and 3,4,5-trihydroxy methylbenzoate (MGA). The hydroxyl radical and hydrogen atom intermediates of water radiolysis react with the solute molecules yielding cyclohexadienyl radicals. The radicals formed in GA and MGA solutions in acid/base catalyzed water elimination decay to phenoxyl radicals. This reaction is not observed in TMBA solution. The hydrated electron intermediate of water decomposition adds to the carbonyl oxygen, the anion thus formed protonates on the ring forming cyclohexadienyl radical or on the carbonyl group forming carbonyl centred radical. The GA intermediates formed during reaction with primary water radicals in presence of oxygen transform to non-aromatic molecules, e.g., to aliphatic carboxylic acids.

A photochemical source of methyl chloride in saline waters.

It is shown experimentallythatthe methoxy group in simple lignin-like molecules can be the source of the methyl group in CH3Cl produced by a photochemical reaction in an aqueous solution of chloride. Terrestrially derived colored dissolved organic matter (CDOM) in river water also yields CH3Cl through a photochemical process in a chloride solution. CDOM extracted from subsurface ocean waters showed some ability to enhance photochemical production of CH3Cl while CDOM from surface water showed no effect. Reactions of the kind described in this paper may be contributors to the marine source of methyl chloride and possibly other alkyl halides.