In situ crosslinkable multi-functional and cell-responsive alginate 3D matrix via thiol-maleimide click chemistry.

In vivo, cells interact with the extracellular matrix (ECM), which provides a multitude of biophysical and biochemical signals that modulate cellular behavior. Inspired by this, we explored a new methodology to develop a more physiomimetic polysaccharide-based matrix for 3D cell culture. Maleimide-modified alginate (AlgM) derivatives were successfully synthesized using DMTMM to activate carboxylic groups. Thiol-terminated cell-adhesion peptides were tethered to the hydrogel network to promote integrin binding. Rapid and efficient in situ hydrogel formation was promoted by thiol-Michael addition "click" chemistry via maleimide reaction with thiol-flanked protease-sensitive peptides. Alginate derivatives were further ionically crosslinked by divalent ions present in the medium, which led to greater stability and allowed longer cell culture periods. By tailoring alginate's biofunctionality we improved cell-cell and cell-matrix interactions, providing an ECM-like 3D microenvironment. We were able to systematically and independently vary biochemical and biophysical parameters to elicit specific cell responses, creating custom-made 3D matrices. DMTMM-mediated maleimide incorporation is a promising approach to synthesizing AlgM derivatives that can be leveraged to produce ECM-like matrices for a broad range of applications, from in vitro tissue modeling to tissue regeneration.

Moldable Tissue-Sealant Hydrogels Composed of In Situ Cross-Linkable Polyethylene Glycol via Thiol-Michael Addition and Carbomers.

Moldable tissue-sealant hydrogels were developed herein by combining the yield stress fluidity of a Carbomer and in situ cross-linking of 3-arm PEG-thiol (PEG-SH) and 4-arm PEG-acrylate (PEG-AC). The Carbomer was mixed with each PEG oligomer to form two aqueous precursors: Carbomer/PEG-SH and Carbomer/PEG-AC. The two hydrogel precursors exhibited sufficient yield stress (>100 Pa) to prevent dripping from their placement on the tissue surface. Moreover, these hydrogel precursors exhibited rapid restructuring when the shear strain was repeatedly changed. These rheological properties contribute to the moldability of these hydrogel precursors. After mixing these two precursors, they were converted from yield-stress fluids to chemically cross-linked hydrogels, Carbomer/PEG hydrogel, via thiol-Michael addition. The gelation time was 5.0 and 11.2 min at 37 and 25 °C, respectively. In addition, the Carbomer/PEG hydrogels exhibited higher cellular viability than the pure Carbomer. They also showed stable adhesiveness and burst pressure resistance to various tissues, such as the skin, stomach, colon, and cecum of pigs. The hydrogels showed excellent tissue sealing in a cecum ligation and puncture model in mice and improved the survival rate due to their tissue adhesiveness and biocompatibility. The Carbomer/PEG hydrogel is a potential biocompatible tissue sealant that surgeons can mold. It was revealed that the combination of in situ cross-linkable PEG oligomers and yield stress fluid such as Carbomer is effective for developing the moldable tissue sealant without dripping of its hydrogel precursors.

DFT and AIMD insights into heterogeneous dissociation of 2-chlorothiophenol on CuO(111) surface: Impact of H2O and OH.

Copper oxides are vital catalysts in facilitating the formation of polychlorinated thianthrenes/dibenzothiophenes (PCTA/DTs) through heterogeneous reactions in high-temperature industrial processes. Chlorothiophenols (CTPs) are the most crucial precursors for PCTA/DT formation. The initial step in this process is the metal-catalyzed production of chlorothiophenoxy radicals (CTPRs) from CTPs via dissociation reactions. This work combines density functional theory (DFT) calculations with ab initio molecular dynamics (AIMD) simulations to explore the formation mechanism of the adsorbed 2-CTPR from 2-CTP, with the assistance of CuO(111). Our study demonstrates that flat adsorption configurations of 2-CTP on the CuO(111) surface are more stable than vertical configurations. The CuO(111) surface acts as a strong catalyst, facilitating the dissociation of 2-CTP into the adsorbed 2-CTPR. Surface oxygen vacancies enhance the adsorption of 2-CTP on the CuO(111) surface, while moderately suppressing the dissociation of 2-CTP. More importantly, water molecules and surface hydroxyl groups actively promote the dissociation of 2-CTP. Specifically, water directly participates in the reaction through "water bridge", enabling a barrier-free process. This research provides molecular-level insights into the heterogeneous generation of dioxins with the catalysis of metal oxides in fly ash from static and dynamic aspects, providing novel approaches for reducing dioxin emissions and establishing dioxin control strategies.

Thiol-functionalized black carbon as effective and economical materials for Cr(VI) removal: Simultaneous sorption and reduction.

Hazardous Cr(VI) continues to pose critical concerns for environmental and public health, demanding the development of effective remediation methods. In this study, thiol-functionalized black carbon (S-BC) was proposed for Cr(VI) removal by mixing thioglycolic acid (TGA) with black carbon (BC) derived from rice straw residue at 80 °C for 8 h. Using a 1:40 (g mL-1) BC-to-TGA ratio, the resulting S-BC40 sample demonstrated significantly enhanced Cr(VI) sorption capacities of 201.23, 145.78, and 106.60 mg g-1 at pH 3.5, 5.5, and 7.5, surpassing its BC counterpart by 2.0, 2.3, and 2.2 times. Additionally, S-BC40 converted all sorbed Cr into Cr(III) species at pH ≥ 5.5, resulting in an equal distribution of Cr(OH)3 and organic Cr(III) complexes. However, approximately 13% of Cr sorbed on BC remained as Cr(VI) at pH 3.5 and 7.5. Both C-centered and S-centered thiyl radicals might contribute to Cr(VI) reduction; however, sufficient C-S groups replenished via thiol-functionalization was the key for the complete Cr(VI) reduction on S-BC samples as pH ≥ 5.5. Thanks to the exceptional Cr(VI) sorption capacity, affordability, and accessibility, thiol-functionalization stands out as a promising modification method for BC. It presents a distinct opportunity to concurrently achieve the objectives of efficient Cr(VI) remediation and waste recycling.

Synthesis of novel bioadhesive hydrogels via facile Thiol-Ene click chemistry for wound healing applications.

Development of outstanding, cost-effective and elastic hydrogels as bioadhesive using Thiol-Ene click chemistry was verified. The visible light photocrosslinkable hydrogels composed of methacrylated chitosan/2,2'-(Ethylenedioxy) diethanethiol formed in presence of eosin-Y photoinitiator. Such hydrogels hold great promise for wound healing applications due to their tunable properties. Main components of hydrogels were extensively characterized using spectroscopic techniques for chemical analysis, thermal analysis, and topologic nanostructure. Various optimization conditions for best gelation time were investigated. Mechanical properties of tensile strength and elongation at break (%) were verified for best wound healing applications. Optimum hydrogel was subjected to for cytotoxicity and microbial suppression evaluation and in-vivo wound healing test for efficient wound healing evaluations. Our results demonstrate the potential use of injectable hydrogels as valuable bioadhesives in bioengineering and biomedical applications, particularly in wound closure and patches.

Moxifloxacin-loaded nanoparticles of thiolated xyloglucan for ocular drug delivery: Permeation, mucoadhesion and pharmacokinetic evaluation.

The current study goal was to improve mucoadhesive potential and ocular pharmacokinetics of nanoparticles of thiolated xyloglucan (TXGN) containing moxifloxacin (MXF). Thiolation of xyloglucan (XGN) was achieved with esterification with 3-mercaptopropionic acid. TXGN was characterized by NMR and FTIR analysis. The nanoparticles of TXGN were prepared using ionic-gelation method and evaluate the antibacterial properties. TXGN and nanoparticles were determined to possess 0.06 and 0.08 mmol of thiol groups/mg of polymer by Ellman's method. The ex-vivo bioadhesion time of TXGN and nanoparticles was higher than XGN in a comparative assessment of their mucoadhesive properties. The creation of a disulfide link between mucus and TXGN is responsible for the enhanced mucoadhesive properties of TXGN (1-fold) and nanoparticles (2-fold) over XGN. Improved MXF penetration in nanoparticulate formulation (80 %) based on TXGN was demonstrated in an ex-vivo permeation research utilizing rabbit cornea. Dissolution study showed 95 % release of MXF from nanoparticles. SEM images of nanoparticles showed spherical shape and cell viability assay showed nontoxic behavior when tested on RPE cell line. Antibacterial analysis revealed a zone of inhibition of 31.5 ± 0.5 mm for MXF, while NXM3 exhibited an expanded zone of 35.5 ± 0.4 mm (p < 0.001). In conclusion, thiolation of XGN improves its bioadhesion, permeation, ocular-retention and pharmacokinetics of MXF.

P-gp inhibition and enhanced oral bioavailability of amikacin Sulfate: A novel approach using Thiolated Chito-PEGylated Lipidic Hybrids.

This study aimed to develop oral lipidic hybrids of amikacin sulfate (AMK), incorporating thiolated chitosan as a P-glycoprotein (P-gp) inhibitor to enhance intestinal absorptivity and bioavailability. Three formulations were designed: PEGylated Liposomes, Chitosan-functionalized PEGylated (Chito-PEGylated) Lipidic Hybrids, and Thiolated Chito-PEGylated Lipidic Hybrids. The physical characteristics of nanovesicles were assessed. Ex-vivo permeation and confocal laser scanning microscopy (CLSM) studies were conducted to evaluate the formulations' potential to enhance AMK intestinal permeability. In-vivo pharmacokinetic studies in rats and histological/biochemical investigations assessed the safety profile and oral bioavailability. The AMK-loaded Thiolated Chito-PEGylated Lipidic Hybrids exhibited favorable physical characteristics, higher ex-vivo permeation parameters, and verified P-gp inhibition via CLSM. They demonstrated heightened oral bioavailability (68.62% absolute bioavailability) and a sufficient safety profile. Relative bioavailability was significantly higher (1556.3% and 448.79%) compared to PEGylated Liposomes and Chito-PEGylated Lipidic Hybrids, respectively, indicating remarkable oral AMK delivery with fewer doses, reduced side effects, and enhanced patient compliance.

An electrochemical sensor based on electrochemically activated carbon cloth and poly (o-aminothiophenol) cross-linked nanogold imprinted layer for the determination of tert-butylhydroquinone.

In this study, an electrochemical sensor based on MoS2 with enhanced electrochemical signals from electrochemically activated carbon cloth (EACC) electrodes and cross-linked o-aminothiophenol functionalized AuNPs (o-ATP@AuNPs) was developed for the detection of the unsaturated vegetable oil antioxidant tert-butylhydroquinone (TBHQ). In this approach, carbon cloth is activated through the implementation of electrochemical methods, thereby effectively increasing its specific surface area. The resulting EACC, serving as an electrode substrate, enables the growth of additional nanomaterials and enhances conductivity. The incorporation of MoS2 effectively augments the sensitivity of the electrochemical sensor. Subsequently, MIP/MoS2/EMCC is formed via electropolymerization, utilizing TBHQ as the template molecule and o-ATP@AuNPs as the functional monomer. The SS bond of o-ATP ensures a strong and stable connection between MoS2 and o-ATP@AuNPs, thereby facilitating the immobilization of MIP. In addition, the high conductivity possessed by o-ATP@AuNPs could effectively improve the sensitivity of the electrochemical sensor. Under the optimal conditions, MIP/MoS2/EMCC could determine TBHQ in the range of 1 × 10-3 µM to 120 µM by differential pulse voltammetry (DPV) with a detection line of 0.72 nM. The proposed MIP/MoS2/EMCC is expected to be applied in the future for the selective and sensitive detection of TBHQ in vegetable oils.

Spectroscopic, electrochemical, and kinetic trends in Fe(III)-thiolate disproportionation near physiologic pH.

In addition to its primary oxygen-atom-transfer function, cysteamine dioxygenase (ADO) exhibits a relatively understudied anaerobic disproportionation reaction (ADO-Fe(III)-SR → ADO-Fe(II) + ½ RSSR) with its native substrates. Inspired by ADO disproportionation reactivity, we employ [Fe(tacn)Cl3] (tacn = 1,4,7-triazacyclononane) as a precursor for generating Fe(III)-thiolate model complexes in buffered aqueous media. A series of Fe(III)-thiolate model complexes are generated in situ using aqueous [Fe(tacn)Cl3] and thiol-containing ligands cysteamine, penicillamine, mercaptopropionate, cysteine, cysteine methyl ester, N-acetylcysteine, and N-acetylcysteine methyl ester. We observe trends in UV-Vis and electron paramagnetic resonance (EPR) spectra, disproportionation rate constants, and cathodic peak potentials as a function of thiol ligand. These trends will be useful in rationalizing substrate-dependent Fe(III)-thiolate disproportionation reactions in metalloenzymes.

Lipoic acid-mediated oral drug delivery system utilizing changes on cell surface thiol expression for the treatment of diabetes and inflammatory diseases.

Lipoic acid (LA), which has good safety and oral absorption, is obtained from various plant-based food sources and needs to be supplemented through human diet. Moreover, substances with a disulfide structure can enter cells through dynamic covalent disulfide exchange with thiol groups on the cell membrane surface. Based on these factors, we constructed LA-modified nanoparticles (LA NPs). Our results showed that LA NPs can be internalized into intestinal epithelial cells through surface thiols, followed by intracellular transcytosis via the endoplasmic reticulum-Golgi pathway. Further mechanistic studies indicated that disulfide bonds within the structure of LA play a critical role in this transport process. In a type I diabetes rat model, the oral administration of insulin-loaded LA NPs exhibited a more potent hypoglycemic effect, with a pharmacokinetic bioavailability of 5.42 ± 0.53%, representing a 1.6 fold enhancement compared to unmodified PEG NPs. Furthermore, a significant upregulation of surface thiols in inflammatory macrophages was reported. Thus, we turned our direction to investigate the uptake behavior of inflammatory macrophages with increased surface thiols towards LA NPs. Inflammatory macrophages showed a 2.6 fold increased uptake of LA NPs compared to non-inflammatory macrophages. Surprisingly, we also discovered that the antioxidant resveratrol facilitates the uptake of LA NPs in a concentration-dependent manner. This is mainly attributed to an increase in glutathione, which is involved in thiol uptake. Consequently, we employed LA NPs loaded with resveratrol for the treatment of colitis and observed a significant alleviation of colitis symptoms. These results suggest that leveraging the variations of thiol expression levels on cell surfaces under both healthy and diseased states through an oral drug delivery system mediated by the small-molecule nutrient LA can be employed for the treatment of diabetes and certain inflammatory diseases.

Hydrogel loaded with thiolated chitosan modified taxifolin liposome promotes osteoblast proliferation and regulates Wnt signaling pathway to repair rat skull defects.

To alleviate skull defects and enhance the biological activity of taxifolin, this study utilized the thin-film dispersion method to prepare paclitaxel liposomes (TL). Thiolated chitosan (CSSH)-modified TL (CTL) was synthesized through charge interactions. Injectable hydrogels (BLG) were then prepared as hydrogel scaffolds loaded with TAX (TG), TL (TLG), and CTL (CTLG) using a Schiff base reaction involving oxidized dextran and carboxymethyl chitosan. The study investigated the bone reparative properties of CTLG through molecular docking, western blot techniques, and transcriptome analysis. The particle sizes of CTL were measured at 248.90 ± 14.03 nm, respectively, with zeta potentials of +36.68 ± 5.43 mV, respectively. CTLG showed excellent antioxidant capacity in vitro. It also has a good inhibitory effect on Escherichia coli and Staphylococcus aureus, with inhibition rates of 93.88 ± 1.59 % and 88.56 ± 2.83 % respectively. The results of 5-ethynyl-2 '-deoxyuridine staining, alkaline phosphatase staining and alizarin red staining showed that CTLG also had the potential to promote the proliferation and differentiation of mouse embryonic osteoblasts (MC3T3-E1). The study revealed that CTLG enhances the expression of osteogenic proteins by regulating the Wnt signaling pathway, shedding light on the potential application of TAX and bone regeneration mechanisms.

Flexible, scalable and simple-fabricated silver nanorod-decorated bacterial nanocellulose SERS substrates cooperated with portable Raman spectrometer for on-site detection of pesticide residues.

Owing to good flexibility, prominent mechanical properties, three-dimensional (3D) nanofibrous structure and low background interference, sustainable bacterial nanocellulose (BNC) is a highly attractive matrix material for surface-enhanced Raman scattering (SERS) sensor. Herein, a highly sensitive, flexible and scalable silver nanorod-decorated BNC (AgNRs@BNC) SERS sensor is developed by a simple vacuum-assisted filtration. The AgNRs were firmly locked in the 3D nanofibrous network of cellulose nanofibers upon vacuum drying process, resulting in the formation of 3D SERS hotspots with a depth of more than 10 µm on the sensor. With 4-aminothiophenol (4-ATP) as a target molecule, a lowest distinguishable level of 10-12 M and a high enhancement factor of 1.1 × 109 were realized by the optimal AgNRs1.5@BNC SERS sensor. Moreover, the AgNRs@BNC SERS sensor exhibits high detectable level of 10-9 M for thiram molecules by integrating with a portable Raman spectrometer. Besides, toxic thiram residues on grape surface could be directly on-site identified by the combination of AgNRs@BNC SERS sensors and a portable Raman spectrometer through a feasible press-and-peel method. The flexible AgNRs@BNC SERS sensor cooperated with portable Raman system demonstrates great potential for on-site detection of pesticide residues on irregular food surfaces.

Synthesis of Glycoconjugates through Chlorooxime-Thiol Conjugation.

Introducing glycans represents an efficient chemical approach to improve the pharmacological properties of therapeutic biomolecules. Herein, we report an efficient synthesis of glycoconjugates through chlorooxime-thiol conjugation. The reactive glycosyl chlorooximes, derived from pyranoses or furanoses, readily couple to a wide range of thiol-containing substrates, including peptides, sugars, and thiophenols. This method features mild reaction conditions and fast kinetics. Capability for aqueous media and gram-scale synthesis demonstrates the potential of this method in the bioconjugation of saccharides with biologically active molecules.

An electrochemical aptasensor based on silver-thiolated graphene for highly sensitive detection of Pb2.

The presence of lead ions (Pb2+) in the environment not only leads to environmental contamination but also poses a significant risk to public health through their migration into food and drinking water. Therefore, the development of rapid and effective techniques for detection of trace amounts of Pb2+ is crucial for safeguarding both the environment and biosafety. In this study, an aptamer-based electrochemical sensor was developed for specific detection of Pb2+ by modifying a polylysine (PLL) coated silver-thiolated graphene (Ag-SH-G) nanocomposite (PLL/Ag-SH-G) on the surface of a glassy carbon electrode, which was further modified with gold nanoparticles (AuNPs) for attachment of aptamers (Apt) that specifically recognized Pb2+. The Ag-SH-G particles were synthesized using a one-step in situ method, resulting in significantly enhanced electrochemical properties upon incorporating Ag nanoparticles into the PLL/Ag-SH-G composite. Coating of the covalently or no-covalently bonded Ag-SH-G particles with PLL provides an excellent supporting matrix, facilitating the assembly of AuNPs and a thiol-modified aptamer for Pb2+. Under optimized conditions, Apt/AuNPs/PLL/Ag-SH-G/GCE exhibited excellent sensing performance for Pb2+ with a wide linear response range (10-1000 nM), a low detection limit (0.047 nM) and extraordinary selectivity. The sensor was employed and satisfactory results were obtained in river water, soil and vegetable samples for the detection of Pb2+.

Light-triggered AND logic tetrapeptide dynamic covalent assembly.

We demonstrate light-triggered dynamic covalent assembly of a linear short tetrapeptide containing two terminal cysteine residues in an AND logic manner. A photobase generator is introduced to accomplish light-mediated pH regulation to increase the reduction potential of thiols in the tetrapeptide, which activates its oxidative polymerization through disulfide bonds. Interestingly, it is elucidated that under light irradiation, mere co-existence of photobase generator and the oxidizing agent permits the polymerization performance of this tetrapeptide. Hence, a light-triggered AND logic dynamic covalent assembly of a tetrapeptide is achieved. Further, upon redox response, the reversible aggregation and disaggregation can be transformed for numerous times due to the dynamic covalent feature of disulfide bond. As a comparison, no assembly occurs for a short peptide containing one terminal cysteine residue under the same stimuli condition. This work offers a new approach to remotely control programmable molecular assembly of short linear peptides based on dynamic covalent bond, holding great potential in wide bioapplications.

1H NMR based sulfonation reaction kinetics of wine relevant thiols in comparison with known carbonyls.

Sulfite addition is a common tool for ensuring wines' oxidative stability via the activity of its free and weakly bound molecular fraction. As a nucleophile, bisulfite forms covalent adducts with wine's most relevant electrophiles, such as carbonyls, polyphenols, and thiols. The equilibrium in these reactions is often represented as dissociation rather than formation. Recent studies from our laboratory demonstrate, first, the acetaldehyde sulfonate dissociation, and second, the chemical stability of cysteine and epicatechin sulfonates under wine aging conditions. Thus, the objective of this study was to monitor by 1H NMR the binding specificity of known carbonyl-derived SO2 binders (acetaldehyde and pyruvic acid) in the presence of S-containing compounds (cysteine and glutathione). We report that during simulated wine aging, the sulfur dioxide that is rapidly bound to carbonyl compounds will be released and will bind to cysteine and glutathione, demonstrating the long-term sulfur dioxide binding potential of S-containing compounds. These results are meant to serve as a complement to existing literature reviews focused on molecular markers related to wines' oxidative stability and emphasize once more the importance of S-containing compounds in wine aging chemical mechanisms.

Mucoadhesive polymers: Design of S-protected thiolated cyclodextrin-based hydrogels.

AIM: This study aims to design chemically crosslinked thiolated cyclodextrin-based hydrogels and to evaluate their mucoadhesive properties via mucosal residence time studies on porcine small intestinal mucosa and on porcine buccal mucosa. METHODS: Free thiol groups of heptakis(6-deoxy-6-thio)-ß-cyclodextrin (ß-CD-SH) were S-protected with 2-mercaptoethanesulfonic acid (MESNA) followed by crosslinking with citric acid. Cytotoxicity was assessed by hemolysis as well as resazurin assay. Hydrogels were characterized by their rheological and mucoadhesive properties. Ritonavir was employed as model drug for in vitro release studies from these hydrogels. RESULTS: The structure of S-protected ß-CD-SH was confirmed by IR and 1H NMR spectroscopy. Degree of thiolation was 390 ± 7 µmol/g. Hydrogels based on native ß-CD showed hemolysis of 12.5 ± 2.5 % and 13.6 ± 2.7 % within 1 and 3 h, whereas hemolysis of just 3.5 ± 2.8 % and 3.9 ± 3.0 % was observed for the S-protected thiolated CD hydrogels, respectively. Both native and S-protected thiolated hydrogels showed minor cytotoxicity on Caco-2 cells. Rheological investigations of S-protected thiolated ß-CD-based hydrogel (16.2 % m/v) showed an up to 13-fold increase in viscosity in contrast to the corresponding native ß-CD-based hydrogel. Mucosal residence time studies showed that thiolated ß-CD-based hydrogel is removed to a 16.6- and 2.4-fold lower extent from porcine small intestinal mucosa and porcine buccal mucosa in comparision to the native ß-CD-based hydrogel, respectively. Furthermore, a sustained release of ritonavir from S-protected thiolated ß-CD-based hydrogels was observed. CONCLUSION: Because of their comparatively high mucoadhesive and release-controlling properties, S-protected thiolated ß-CD-based hydrogels might be promising systems for mucosal drug delivery.

From molecules to medicine: thiol selective bioconjugation in synthesis of diagnostic and therapeutic radiopharmaceuticals.

Radiolabeling of biomolecules and cells with radiolabeled prosthetic groups has significant implications for nuclear medicine, imaging, and radiotherapy. Achieving site-specific and controlled incorporation of radiolabeled prostheses under mild reaction conditions is crucial for minimizing the impact on the bioactivity of the radiolabeled compounds. The targeting of natural and abundant amino acids during radiolabeling of biomolecules often results in nonspecific and uncontrolled modifications. Cysteine is distinguished by its low natural abundance and unique nucleophilicity. It is therefore an optimal target for site-selective and site-specific radiolabeling of biomolecules under controlled parameters. This review extensively discusses thiol-specific radiolabeled prosthetic groups and provides a critical analysis and comprehensive study of the synthesis of these groups, their in vitro and in vivo stability profiles, reaction kinetics, stability of resulting adducts, and overall impact on the targeting ability of radiolabeled biomolecules. The insights presented here aim to facilitate the development of highly efficient radiopharmaceuticals, initially in preclinical settings and ultimately in clinical applications.

NIR Fluorescent/Photoacoustic Bimodal Imaging of Ferroptosis in Pancreatic Cancer Using Biothiols-Activable Probes.

Ferroptosis modulation is a powerful therapeutic option for pancreatic ductal adenocarcinoma (PDAC) with a low 5-year survival rate and lack of effective treatment methods. However, due to the dual role of ferroptosis in promoting and inhibiting pancreatic tumorigenesis, regulating the degree of ferroptosis is very important to obtain the best therapeutic effect of PDAC. Biothiols are suitable as biomarkers of imaging ferroptosis due to the dramatic decreases of biothiol levels in ferroptosis caused by the inhibited synthesis pathway of glutathione (GSH) and the depletion of biothiol by reactive oxygen species. Moreover, a very recent study reported that cysteine (Cys) depletion can lead to pancreatic tumor ferroptosis in mice and may be employed as an effective therapeutic strategy for PDAC. Therefore, visualization of biothiols in ferroptosis of PDAC will be helpful for regulating the degree of ferroptosis, understanding the mechanism of Cys depletion-induced pancreatic tumor ferroptosis, and further promoting the study and treatment of PDAC. Herein, two biothiol-activable near-infrared (NIR) fluorescent/photoacoustic bimodal imaging probes (HYD-BX and HYD-DX) for imaging of pancreatic tumor ferroptosis were reported. These two probes show excellent bimodal response performances for biothiols in solution, cells, and tumors. Subsequently, they have been employed successfully for real-time visualization of changes in concentration levels of biothiols during the ferroptosis process in PDAC cells and HepG2 cells. Most importantly, they have been further applied for bimodal imaging of ferroptosis in pancreatic cancer in mice, with satisfactory results. The development of these two probes provides new tools for monitoring changes in concentration levels of biothiols in ferroptosis and will have a positive impact on understanding the mechanism of Cys depletion-induced pancreatic tumor ferroptosis and further promoting the study and treatment of PDAC.

Redox proteomics in melanoma cells: An optimized protocol.

Cancer development and progression are intimately related with post-translational protein modifications, e.g., highly reactive thiol moiety of cysteines enables structural rearrangements resulting in redox biological switches. In this context, redox proteomics techniques, such as 2D redox DIGE, biotin switch assay and OxIcat are fundamental tools to identify and quantify redox-sensitive proteins and to understand redox mechanisms behind thiol modifications. Given the great variability in redox proteomics protocols, problems including decreased resolution of peptides and low protein amounts even after enrichment steps may occur. Considering the biological importance of thiol's oxidation in melanoma, we adapted the biotin-switch assay technique for melanoma cells in order to overcome the limitations and improve coverage of detected proteins.