H2S Release Research Articles

Infection Microenvironment-Responsive Coating on Titanium Surfaces for On-Demand Release of Therapeutic Gas and Antibiotic.

Aseptic loosening and bacterial infection pose significant challenges in the clinical application of titanium (Ti) orthopedic implants, which are primarily caused by insufficient osseointegration and bacterial contamination. To address these issues, a responsive coating on Ti surface is constructed, which achieves enhanced osseointegration and infection elimination by on-demand release of therapeutic gas hydrogen sulfide (H2S) and antibiotic. TiO2 nanotubes (TNT) are anodized on the Ti surface to enhance its bioactivity and serve as reservoirs for the antibiotic. An infection microenvironment-responsive macromolecular H2S donor layer is coated on top of TNT to inhibit premature leakage of antibiotic. This layer exhibits a sustained release of low-dosage H2S, which is capable of promoting the osteogenic differentiation and migration of cells. Moreover, the compactness of the macromolecular H2S donor layer could be broken by bacterial invasion, leading to rapid antibiotic release thus preventing infection. In vitro antibacterial experiments validates significant antibacterial activity of the coating against both Gram-negative (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus). Crucially, this coating effectively suppresses implant-associated infection with 98.7% antibacterial efficiency in a rat femoral bone defect model, mitigates inflammation at the defect site and promotes osseointegration of the Ti orthopedic implant.

Cable bacteria delay euxinia and modulate phosphorus release in coastal hypoxic systems.

Cable bacteria are long, filamentous bacteria with a unique metabolism involving centimetre-scale electron transport. They are widespread in the sediment of seasonally hypoxic systems and their metabolic activity stimulates the dissolution of iron sulfides (FeS), releasing large quantities of ferrous iron (Fe2+) into the pore water. Upon contact with oxygen, Fe2+ oxidation forms a layer of iron(oxyhydr)oxides (FeOx), which in its turn can oxidize free sulfide (H2S) and trap phosphorus (P) diffusing upward. The metabolism of cable bacteria could thus prevent the release of H2S from the sediment and reduce the risk of euxinia, while at the same time modulating P release over seasonal timescales. However, experimental support for this so-called 'iron firewall hypothesis' is scarce. Here, we collected natural sediment in a seasonally hypoxic basin in three different seasons. Undisturbed sediment cores were incubated under anoxic conditions and the effluxes of H2S, dissolved iron (dFe) and phosphate (PO4 3-) were monitored for up to 140 days. Cores with recent cable bacterial activity revealed a high stock of sedimentary FeOx, which delayed the efflux of H2S for up to 102 days. Our results demonstrate that the iron firewall mechanism could exert an important control on the prevalence of euxinia and regulate the P release in coastal oceans.

Effect of different digestate biochars as promoters via sludge anaerobic digestion on subsequent pyrolysis products: Focusing on the nitrogen, sulfur, and chlorine releasing characteristics

Anaerobic digestion generates a significant amount of byproduct known as digestate, necessitating resourceful disposal. However, the digestate biochar may exert certain impacts on the pyrolysis of sludge, especially regarding the release of N/S/Cl during the pyrolysis process. This may lead to environmental risks and impose restrictions on the recycling of digestate. There is limited existing research on this topic. In this study, the impact and mechanism of digestate biochar on pyrolysis products were analyzed through kinetic analysis, TG-MS, and Py-GC/MS, with a specific focus on the release characteristics of polluting elements during the pyrolysis process. The findings indicate that the Fe-containing digestate biochar, owing to the larger specific surface area, richer functional groups and catalytic activity associated with Fe3+, enhances the production of C/H/O gases during pyrolysis while reducing the release of NH3, NO2, and H2S. Particularly, Fe-containing digestate biochar significantly enhances the release of Cl-containing gases. The decrease in tar content indicates that Fe-containing digestate biochar promotes the catalytic removal of tar. A comprehensive comparison and analysis of the reaction mechanism were conducted in this study, providing a theoretical basis for the release of pollutants from digestate pyrolysis while enhancing the control and management of pollutants containing N/S/Cl.

A fluorescent probe for detecting H2O2 and delivering H2S in lysosomes and its application in maintaining the redox environments

Hydrogen peroxide (H2O2) is a reactive oxygen species (ROS) that can be used as a marker for the occurrence of oxidative stress in the organism. Lysosomes serve as intracellular digestive sites, and when the concentration of H2O2 in them is abnormal, lysosomal function is often impaired, leading to the development of diseases. Hydrogen sulfide (H2S) acts as a gaseous signaling molecule that scavenges H2O2 from cells and tissues, thereby maintaining the redox environment of the body. However, most of the reported hydrogen peroxide fluorescent probes so far can only detect H2O2, but cannot maintain the intracellular redox environment. In this paper, an H2O2 fluorescent probe LN-HOD with lysosomal targeting properties was designed and synthesized by combining the H2O2 recognition site with a naphthylamine fluorophore via a thiocarbamate moiety. The probe has the advantages of large Stokes shift (110 nm), high sensitivity and good H2S release capability. The probe LN-HOD can be used to detect H2O2 in cells, zebrafish and plant roots. In addition, LN-HOD detects changes in the concentration of H2O2 in plant roots when Arabidopsis is stressed by cadmium ion (Cd2+). And through its ability to release H2S, it can help to remove excess H2O2 and maintain the redox environment in cells, zebrafish and plant roots. The present work provides new ideas for the detection and assisted removal of H2O2, which contributes to the in-depth study of the cellular microenvironment in organisms.

Using the sulfide-oxidizing bacterium Geobacillus thermodenitrificans to restrict H2S release during chicken manure composting

Hydrogen sulfide (H2S) is a toxic gas massively released during chicken manure composting. Diminishing its release requires efficient and low cost methods. In recent years, heterotrophic bacteria capable of rapid H2S oxidation have been discovered but their applications in environmental improvement are rarely reported. Herein, we investigated H2S oxidation activity of a heterotrophic thermophilic bacterium Geobacillus thermodenitrificans DSM465, which contains a H2S oxidation pathway composed by sulfide:quinone oxidoreductase (SQR) and persulfide dioxygenase (PDO). This strain rapidly oxidized H2S to sulfane sulfur and thiosulfate. The oxidation rate reached 5.73 μmol min−1·g−1 of cell dry weight. We used G. thermodenitrificans DSM465 to restrict H2S release during chicken manure composting. The H2S emission during composting process reduced by 27.5% and sulfate content in the final compost increased by 34.4%. In addition, this strain prolonged the high temperature phase by 7 days. Thus, using G. thermodenitrificans DSM465 to control H2S release was an efficient and economic method. This study provided a new strategy for making waste composting environmental friendly and shed light on perspective applications of heterotrophic H2S oxidation bacteria in environmental improvements.

Glycosidase-activated H2S donorsto enhance chemotherapy efficacy

Hydrogen sulfide (H2S) plays a critical role in cancer biology. Herein, we developed a series of glycosidase-triggered hydrogen sulfide (H2S) donors by connecting sugar moieties (including glucose, galactose and mannose) to COS donors via a self-immolative spacer. In the presence of corresponding glycosidases, H2S was gradually released from these donors in PBS buffer with releasing efficiencies from 36 to 67 %. H2S release was also detected by H2S probe WSP-1 after treatment HepG2 cells with Man1. Cytotoxicities of these glycosylated H2S donors were evaluated against HepG2 by MTT assay. Among them, Man1 and Man2 exhibited an obvious reduction of cell viability in HepG2 cells, with cell viability as 37.6 % for 80 μM of Man. Consistently, significant apoptosis was observed in HepG2 cells after treatment with Man1 and Man2. Finally, We evaluated the potential of Man1 for combination therapy with doxorubicin. A synergistic effect was observed between Man1 and Doxorubicin in HepG2 and Hela cells. All these results indicated glycosidase-activated H2S donorshave promising potential for cancer therapy.

Periodic injection of liquefied kitchen and food waste in municipal solid waste: Effects on leachate and gas generation

With continuous advancements in the zero-waste strategy in China, transportation of fresh municipal solid waste to landfills has ceased in most first-tier cities. Consequently, the production of landfill gas has sharply declined because the supply of organic matter has decreased, rendering power generation facilities idle. However, by incorporating liquefied kitchen and food waste (LKFW), sustainable methane production can be achieved while consuming organic wastewater. In this study, LKFW and water (as a control group) were periodically injected into high and low organic wastes, respectively. The biochemical characteristics of the resulting gas and leachate were analyzed. LKFW used in this research generated 19.5–37.6 L of methane per liter in the post-methane production phase, highlighting the effectiveness of LKFW injection in enhancing the methane-producing capacity of the system. The release of H2S was prominent during both the rapid and post-methane production phases, whereas that of NH3 was prominent in the post-methane production phase. As injection continued, the concentrations of chemical oxygen demand, 5-d biological oxygen demand, total organic carbon, ammonia nitrogen, total nitrogen, and oil in the output leachate decreased and eventually reached levels comparable to those in the water injection cases. After nine rounds of injections, the biologically degradable matter of the two LKFW-injected wastes decreased by 8.2 % and 15.1 %, respectively. This study sheds light on determining the organic load, controlling odor, and assessing the biochemical characteristics of leachate during LKFW injection.

A Multichannel Metabolic Pathway Interference Strategy for Complete Energy Depletion‐Mediated Cancer Therapy

AbstractHydrogen sulfide (H2S) is being progressively integrated as an emerging inhibitor of the electron transport chain in energy interference‐based tumor therapy. However, metabolic reprogramming in cancer cells causes both oxidative phosphorylation (OXPHOS) and glycolysis to occur simultaneously, which contributes to the ineffective therapeutic effect of blocking a single pathway. To achieve complete suppression of energy production, an inorganic H2S donor ZnS@ZIF‐8@CaP nanoparticle (ZSZC NP) carrying Ca and Zn is constructed for achieving simultaneous interference of OXPHOS and glycolysis. The core–shell ZSZC nanoparticles can break down in the tumor microenvironment. This leads to a sustained H2S release and calcium overload to disrupt the normal functioning of mitochondria by inhibiting the expression of cytochrome c and causing damage to mitochondrial membrane potential. Meanwhile, the presence of Zn2+ hinders the typical process of glycolysis by impeding the functioning of lactate dehydrogenase and glyceraldehyde‐3‐phosphate dehydrogenase. The synchronous interference of OXPHOS and glycolysis hampers the energy supply to cancer cells. Additionally, H2S and calcium overload can expedite tumor necrosis in vivo by inducing cellular acidification and calcification. Therefore, this energy‐blocking strategy will completely deplete the energy reserves of cancer cells and provide new insights for exploring bioenergetic inhibition as a treatment approach.

The Antioxidant Properties of Glucosinolates in Cardiac Cells Are Independent of H2S Signaling.

The organic sulfur-containing compounds glucosinolates (GSLs) and the novel gasotransmitter H2S are known to have cardioprotective effects. This study investigated the antioxidant effects and H2S-releasing potential of three GSLs ((3E)-4-(methylsulfanyl)but-3-enyl GSL or glucoraphasatin, 4-hydroxybenzyl GSL or glucosinalbin, and (RS)-6-(methylsulfinyl)hexyl GSL or glucohesperin) in rat cardiac cells. It was found that all three GSLs had no effect on cardiac cell viability but were able to protect against H2O2-induced oxidative stress and cell death. NaHS, a H2S donor, also protected the cells from H2O2-stimulated oxidative stress and cell death. The GSLs alone or mixed with cysteine, N-acetylcysteine, glutathione, H2O2, iron and pyridoxal-5'-phosphate, or mouse liver lysates did not induce H2S release. The addition of GSLs also did not alter endogenous H2S levels in cardiac cells. H2O2 significantly induced cysteine oxidation in the cystathionine gamma-lyase (CSE) protein and inhibited the H2S production rate. In conclusion, this study found that the three tested GSLs protect cardiomyocytes from oxidative stress and cell death but independently of H2S signaling.

Regulating H2S release from self-assembled peptide H2S-donor conjugates using cysteine derivatives.

Self-assembled peptides provide a modular and diverse platform for drug delivery, and innovative delivery methods are needed for delivery of hydrogen sulfide (H2S), an endogenous signaling molecule (gasotransmitter) with significant therapeutic potential. Of the available types of H2S donors, peptide/protein H2S donor conjugates (PHDCs) offer significant versatility. Here we discuss the design, synthesis, and in-depth study of a PHDC containing three covalently linked components: a thiol-triggered H2S donor based on an S-aroylthiooxime (SATO), a GFFF tetrapeptide, and a tetraethylene glycol (TEG) dendron. Conventional transmission electron microscopy showed that the PHDC self-assembled into spherical structures without heat or stirring, but it formed nanofibers with gentle heat (37 °C) and stirring. Circular dichroism (CD) spectroscopy data collected during self-assembly under nanofiber-forming conditions suggested an increase in β-sheet character and a decrease in organization of the SATO units. Release of H2S from the nanofibers was studied through triggering with various thiols. The release rate and total amount of H2S released over both short (5 h) and long (7 d) time scales varied with the charge state: negatively charged and zwitterionic thiols (e.g., Ac-Cys-OH and H-Cys-OH) triggered release slowly while a neutral thiol (Ac-Cys-OMe) showed ∼10-fold faster release, and a positively charged thiol (H-Cys-OMe) triggered H2S release nearly 50-fold faster than the negatively charged thiols. CD spectroscopy studies monitoring changes in secondary structure over time during H2S release showed similar trends. This study sheds light on the driving forces behind self-assembling nanostructures and offers insights into tuning H2S release through thiol charge state modulation.

An injectable hydrogel dressing for controlled release of hydrogen sulfide pleiotropically mediates the wound microenvironment.

The healing of scalded wounds faces many challenges such as chronic inflammation, oxidative stress, wound infection, and difficulties in vascular and nerve regeneration. Treating a single problem cannot effectively coordinate the complex regenerative microenvironment of scalded wounds, limiting the healing and functional recovery of the skin. Therefore, there is a need to develop a multi-effect treatment plan that can adaptively address the issues at each stage of wound healing. In this study, we propose a scheme for on-demand release of hydrogen sulfide (H2S) based on the concentration of reactive oxygen species (ROS) in the wound microenvironment. This is achieved by encapsulating peroxythiocarbamate (PTCM) in the ROS-responsive polymer poly(ethylene glycol)-poly(L-methionine) (PMet) to form nanoparticles, which are loaded into a thermosensitive injectable hydrogel, F127-poly(L-aspartic acid-N-hydroxysuccinimide) (F127-P(Asp-NHS)), to create a scald dressing. The H2S released by the hydrogel dressing on demand regulates the wound microenvironment by alleviating infection, reducing oxidative stress, and remodeling inflammation, thereby accelerating the healing of full-thickness scalded wounds. This hydrogel dressing for the adaptive release of H2S has great potential in addressing complex scalded wounds associated with infection and chronic inflammation.

Inflammatory-stimuli-responsive turn-on NIR fluorogenic theranostic prodrug: adjuvant delivery of diclofenac and hydrogen sulfide attenuates acute inflammatory disorders.

Prolonged use of very commonly prescribed non-steroidal anti-inflammatory drugs (NSAIDs) is often associated with undesired side effects, including gastrointestinal ulcers due to the non-selective inhibition of cyclooxygenases. We describe the development of an inflammatory-stimuli-responsive turn-on fluorogenic theranostic prodrug DCF-HS for adjuvant drug delivery. Upon activation by reactive oxygen species (ROS), the prodrug releases diclofenac DCF (active drug) and the NIR fluorophore DCI-NH2 along with carbonyl sulfide (COS). The second activation of COS by the enzyme carbonic anhydrase (CA) generates hydrogen sulfide (H2S). The prodrug was conveniently synthesized using multi-step organic synthesis. The UV-Vis and fluorescence studies revealed the selective reactivity of DCF-HS towards ROS such as H2O2 in the aqueous phase and the desired uncaging of the drug DCF with turn-on NIR fluorescent reporter under physiological conditions. Furthermore, the release of fluorophore DCI-NH2 and drug DCF was confirmed using the reverse phase HPLC method. Compatibility of prodrug activation was studied next in the cellular medium. The prodrug DCF-HS was non-toxic in a representative cancer cell line (HeLa) and a macrophage cell line (RAW 264.7) up to 100 μM concentration, indicating its biocompatibility. The intracellular ROS-mediated activation of the prodrug with the release of NIR dye DCI-NH2 and H2S was investigated in HeLa cells using the H2S-selective probe WSP2. The anti-inflammatory activity of the active drug DCF from the prodrug DCF-HS was studied in the lipopolysaccharide (LPS)-induced macrophage cell line and compared to that of the parent drug DCF using western blot analysis and it was found that the active drug resulted in pronounced inhibition of COX-2 in a dose-dependent manner. Finally, the anti-inflammatory potential of the prodrug and the turn-on fluorescence were validated in the inflammation-induced Wister rat models.

Liposome-coated nanoparticle triggers prostate cancer ferroptosis through synergetic chemodynamic-gas therapy.

Ferroptosis has attracted much attention for tumor treatment. It has been recently identified that castration-resistant prostate cancer (CRPC) is vulnerable to ferroptosis inducers. Notably, chemodynamic therapy (CDT), triggered by metal ions, could easily induce ferroptosis via a Fenton/Fenton-like reaction, but its efficiency was highly dependent on the intracellular H2O2 concentration, posing significant changes for its clinical translation. Herein, we attached glucose oxidase (GOx) onto the surface of manganese sulfide (MnS) and developed therapeutic nanocomposites (Lpo@MnS-GOx) after encapsulating with liposome. Upon internalization by cancer cells, the released GOx could transform glucose into gluconic acid (GA) and H2O2. Notably, the generated GA stimulates the degradation of MnS, followed by the promotion of the release of H2S and Mn2+, whereas the produced H2O2 can amplify the Fenton-like response initiated by Mn2+. The enhanced CDT combined with the gas therapy effect could simultaneously promote the accumulation of reactive oxygen species and finally induce ferroptosis and exhibit an excellent anti-tumor effect. Consequently, these Lpo@MnS-GOx NPs with enhanced ferroptosis-induced effect will find great potential for CRPC cancer treatment.

Analysis of Polysulfides in Aged Sparkling Wines From Different Vintages

Traditional sparkling wines are obtained from a vinification process with an additional ‘second’ fermentation in the bottle, which has an essential impact on the sensorial characteristics. During this maturation phase, several compounds are released from the yeast in autolysis, including the tripeptide glutathione. This compound has recently gained more interest due to its role in the formation of polysulfides and the subsequent possibility of H2S release post‐bottling. Hence, the release of sulphur‐containing compounds like glutathione during an ageing ‘sur lies’ ought to be considered regarding the accumulation and persistence of polysulfides. In this study, the presence of polysulfides in traditional sparkling wines was validated to gain a preliminary understanding of the role of ageing time and glutathione. UHPLC‐HRMS allowed the detection of two glutathionyl trisulfides in a selection of different naturally sparkling wines. Besides, it was found that the wines from vintage 2020 had a relatively high formation of GS3G and GS3C compared to vintages 2018 and 2019. Moreover, a trend between the trisulfides and GSSC was observed, possibly related to glutathione condensation and cysteine uptake by the yeast. This study showed the presence of polysulfides in various sparkling wines for the first time, increasing the availability of the current knowledge on this topic.

A cysteine-activated fluorescent H2S donor for visualizing H2S release and alleviating cellular inflammation.

We developed Bcy-NCS, a Cys-specific fluorescent H2S donor with a self-immolative spacer, overcoming the issue of multiple fluorophore release seen in traditional ICT-based donors. Bcy-NCS selectively responds to Cys, releases H2S, and enables fluorescence-based monitoring. It also reduces LPS-induced inflammation in RAW 264.7 cells, indicating potential for inflammation treatment.

A small-diameter vascular graft promotes rapid and benign remodeling of the neointima through dual release of nitric oxide and hydrogen sulfide

Coronary artery bypass grafting often requires autologous veins as alternatives. The limited source and problem of over-expansion are major obstacles for vein grafts, which could be solved by small-diameter artificial vascular graft. However, their clinical application is limited by thrombosis and restenosis caused by incomplete endothelialization and abnormal smooth muscle cells (SMCs) proliferation. Nitric oxide (NO) and hydrogen sulfide (H2S) are crucial signaling molecules in the cardiovascular system, known to regulate endothelial cells(ECs) and SMCs proliferation, migration, reduce oxidative stress, and inhibit inflammation to prevent intimal hyperplasia. In this study, we developed a new method to prepare a keratin based H2S donor(KAT) complexed with copper ions and electrospun it with PCL to prepare PCL/KAT-Cu small-diameter tissue-engineered vascular graft, which is capable of dual release of NO and H2S. We investigated the effects of NO and H2S release on human umbilical vein endothelial cells (HUVECs) and human umbilical arterial smooth muscle cells(HUASMCs) proliferation and migration, evaluated the graft's selectivity for HUVECs, and assessed its effects on macrophage phenotypic transitions and its protective effect on HUVECs under reactive oxygen species (ROS) conditions. Additionally, we tested the graft's ability to rapidly endothelialize under shear force using an in vitro 3D-perfusion system. After one month of in situ transplantation in rat abdominal aorta, the PCL/KAT-Cu small-diameter tissue-engineered vascular grafts demonstrated satisfactory intimal remodeling, comparable to natural blood vessels. In conclusion, our study presents a promising new strategy for remodeling small-diameter vascular grafts.

Growth Mechanism and Film Properties of Atomic-Layer-Deposited Titanium Oxysulfide

Titaniumoxysulfide (TiOxSy) is a technologically-relevant material for batteries, catalysis and, the area of our focus: photovoltaics. One of the key merits of TiOxSy is the wide range of electrical conductivity and optical absorption that can be achieved by tuning its composition. In this contribution, we present a supercycle-based ALD approach for TiOxSy which combines ALD of amorphous TiO2 and semimetallic two-dimensional (2D) TiS2, and uses tetrakis(dimethylamido)titanium (TDMATi), H2O and H2S as precursors. While ALD with supercycles is generally acknowledged to give a high level of control over film composition, in this case of TiOxSy we show through a variety of in-situ techniques that many effects occur during the ALD supercycles that strongly affect the film growth and resulting film properties. Yet, by understanding and taking these effects into account, the supercycle process allows for accurate tailoring between pure TiOx and TiSx. The effects of study focus mainly on exchange reactions and the film crystal morphology and its effect on the growth rate. Exchange reactions: QMS measurements show that during supercycle ALD, strong exchange reactions occur during the H2O dosing step, where exchange occurs between underlying TiSx and H2O, resulting in the formation of TiOx and release of H2S. The exchange reactions and their effect on the film growth were studied in-depth using in-situ SE. From these studies, it was found that during ALD TiO2 cycles on TiSx, the exchange reactions behave similarly at 100 and 150 °C, while being more pronounced at 200 °C. Specifically, at 100 and 150 °C, the reactions persist for about seven cycles and stop once approximately 3−4 Å of TiO2 has grown, while at 200 °C, the reactions are more prominent and persist for about nine cycles and stop once approximately 5 Å of TiO2 has grown. This TiO2 forms both through back-oxidation of underlying TiSx and by ALD of TiO2 on top. These exchange effects are thus less prominent at lower growth temperatures, facilitating more accurate control over composition. Film crystallinity: Interestingly, the pure ALD TiO2 and TiS2 processes yield films of very different morphology. Whereas ALD TiO2 at these temperatures results in smooth, amorphous films that grow with a constant growth-per-cycle (GPC), in the case of pure ALD 2D-TiSx the growth process is more intricate: Electron microscopy shows that these 2D films initially have crystal growth that occurs laterally, up to the point of coalescence where the 2D layers start to grow out of plane. As ALD growth on the sideplanes of the 2D material is much faster, the GPC of these films keeps increasing as the film thickness progresses. When combining ALD TiO2 and TiS2 in a supercycle, the TiO2 cycles interrupt the growth of the 2D TiS2 crystals. This not only leads to a lower crystallinity of the film, but due to suppression of the reactive 2D-TiS2 edges, also the GPC is strongly reduced. As such, this effect has a strong influence on the resulting film thickness and composition, which is markedly different than would be expected than on the basis of the constituent ALD cycles in the supercycle.Based on the insights, we present a model that can explain the relation between supercycle ratio, deposition temperature and the resulting film properties. This enables the control over film conductivity over six orders of magnitude, where Hall measurements show that S-rich films exhibit both higher carrier densities and carrier mobility. Similary, controlling the composition allows tuning the optical properties between opaque, semimetallic 2D-TiS2 and transparent, dielectric TiO2 with a bandgap a little over 3 eV.Since exchange reactions and film crystallinity are common factors in ALD films, we expect these results to be of broader interest to the ALD community, for those preparing multicomponent materials using supercycles Figure 1

An injectable and adaptable hydrogen sulfide delivery system for modulating neuroregenerative microenvironment.

Peripheral nerve regeneration is a complex physiological process. Single-function nerve scaffolds often struggle to quickly adapt to the imbalanced regenerative microenvironment, leading to slow nerve regeneration and limited functional recovery. In this study, we demonstrate a "pleiotropic gas transmitter" strategy based on endogenous reactive oxygen species (ROS), which trigger the on-demand H2S release at the defect area for transected peripheral nerve injury (PNI) repair through concurrent neuroregeneration and neuroprotection processing. This H2S delivery system consists of an H2S donor (peroxyTCM) encapsulated in a ROS-responsive polymer (mPEG-PMet) and loaded into a temperature-sensitive poly (amino acid) hydrogel (mPEG-PA-PP). This multi-effect combination strategy greatly promotes the regeneration of PNI, attributed to the physiological effects of H2S. These effects include the inhibition of inflammation and oxidative stress, protection of nerve cells, promotion of angiogenesis, and the restoration of normal mitochondrial function. The adaptive release of pleiotropic messengers to modulate the tissue regeneration microenvironment offers promising peripheral nerve repair and tissue engineering opportunities.

Searching for Novel Sources of Hydrogen Sulfide Donors: Chemical Profiling of Polycarpa aurata Extract and Evaluation of the Anti-Inflammatory Effects.

Hydrogen sulfide (H2S) is a signaling molecule endogenously produced within mammals' cells that plays an important role in inflammation, exerting anti-inflammatory effects. In this view, the research has shown a growing interest in identifying natural H2S donors. Herein, for the first time, the potential of marine extract as a source of H2S-releasing agents has been explored. Different fractions obtained by the Indonesian ascidian Polycarpa aurata were evaluated for their ability to release H2S in solution. The main components of the most active fraction were then characterized by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and NMR spectroscopy. The ability of this fraction to release H2S was evaluated in a cell-free assay and J774 macrophages by a fluorimetric method, and its anti-inflammatory activity was evaluated in vitro and in vivo by using carrageenan-induced mouse paw edema. The anti-inflammatory effects were assessed by inhibiting the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), and interleukin-6 (IL-6), coupled with a reduction in nitric oxide (NO) and IL-6 levels. Thus, this study defines the first example of a marine source able to inhibit inflammatory responses in vivo through the release of H2S.

The crucial role of nMOFs in H2S absorption process using ionic liquid solution based nanofluid systems

Ionic liquid solutions based of polyamines were synthesized and used for H2S removal. The results of simulation calculation and characterization showed that ionic liquid trap H2S by forming hydrogen bonds. Five nanometer-sized MOFs (nMOFs) were synthesized and added into ionic liquid solutions to build nanofluid systems. The effects of types, particle size, concentration, and regeneration gas of nanoparticles on the desulfurization performance of different nanofluids were explored. The addition of nMOFs with appropriate types and concentrations showed significant enhancement effect on the H2S absorption of liquid. Among five nMOFs, the systems of HKUST-1 and MIL-101(Fe) had high enhancement as well as regeneration performance at low concentrations (0.05 %). Based on sweep effect, gas–liquid mass transfer was enhanced by nMOFs due to the quickly capture and release of H2S. Furthermore, in this work, an “enrichment effect” has been proposed, in which H2S molecular enrichment zones were formed around nanoparticles, promoting gas–liquid reactions. The nanoparticles at different stages were characterized using X-ray photoelectron spectroscopy, scanning electron microscope, transmission electron microscope and energy dispersive spectrum, and the results confirmed that nMOFs have the ability to enrich H2S, which play a catalyst-like and accelerator-like role in H2S absorption process.