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Label-free electrochemical biosensors show great potential for the development of point-of-care devices (POCDs) for environmental and clinical applications. These sensors operate with shorter analysis times and are more economic than the labelled ones. Here, four completely label-free biosensors without electron transfer mediators were developed for hepatitis B virus (HBV) detection. The approach consisted in (i) the modification of gold surfaces with cysteamine (CT) or cysteine (CS) linkers, (ii) the subsequent antibody (Ab) immobilization, either directly by hydrogen bonding (HB) interactions or by covalent bonds (CB) using additional reagents, and (iii) measuring the biosensor response by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The electrode surfaces at each stage of the modification process were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of Ab immobilization by HB with the DPV analysis displayed improved repeatability, lower interference to serum matrix and similar limits of detection and quantification than the traditional biosensors that immobilize the Ab via CB and use EIS as readout technique. The Ab immobilization by HB is shown as a simple, efficient and low-cost alternative to CB ones, while DPV was faster and showed better performance than EIS. The CT-HB biosensor displayed the lowest limits of detection and quantification of 0.14 and 0.46 ng/mL, respectively, a 0.46-12.5 ng/mL linear analytical range, and 100% of recovery for 1/10 human serum media during HBV surface antigen detection by DPV. Even, it preserved the initial sensing capability after 7 days of its fabrication., (© 2024. The Author(s).)

This study conducts a comparative analysis of cystamine (RSSR), a disulfide, and cysteamine (RSH), its thiol monomer, to evaluate their efficacy as radioprotectors and antioxidants under high linear energy transfer (LET) and high-dose-rate irradiation conditions. It examines their interactions with reactive primary species produced during the radiolysis of the aqueous ferrous sulfate (Fricke) dosimeter, offering insights into the mechanisms of radioprotection and highlighting their potential to enhance the therapeutic index of radiation therapy, particularly in advanced techniques like FLASH radiotherapy. Using Monte Carlo multi-track chemical modeling to simulate the radiolytic oxidation of ferrous to ferric ions in Fricke-cystamine and Fricke-cysteamine solutions, this study assesses the radioprotective and antioxidant properties of these compounds across a variety of irradiation conditions. Concentrations were varied in both aerated (oxygen-rich) and deaerated (hypoxic) environments, simulating conditions akin to healthy tissue and tumors. Both cystamine and cysteamine demonstrate radioprotective and strong antioxidant properties. However, their effectiveness varies significantly depending on the concentration employed, the conditions of irradiation, and whether or not environmental oxygen is present. Specifically, excluding potential in vivo toxicity, cysteamine substantially reduces the adverse effects of ionizing radiation under aerated, low-LET conditions at concentrations above ~1 mM. However, its efficacy is minimal in hypoxic environments, irrespective of the concentration used. Conversely, cystamine consistently offers robust protective effects in both oxygen-rich and oxygen-poor conditions. The distinct protective capacities of cysteamine and cystamine underscore cysteamine's enhanced potential in radiotherapeutic settings aimed at safeguarding healthy tissues from radiation-induced damage while effectively targeting tumor tissues. This differential effectiveness emphasizes the need for personalized radioprotective strategies, tailored to the specific environmental conditions of the tissue involved. Implementing such approaches is crucial for optimizing therapeutic outcomes and minimizing collateral damage in cancer treatment.

The physiological and clinical importance of Glutathione and Cysteamine is emphasized by their participation in a range of conditions, such as diabetes, cancer, renal failure, Parkinson's disease, and hypothyroidism. This necessitates the requirement for accessible, expedited, and cost-efficient testing that can facilitate clinical diagnosis and treatment options. This article examines numerous techniques used to detect both glutathione and cysteamine. The discussed methods include electroanalytical techniques such as voltammetry and amperometry, which are examined for their sensitivity and ability to provide real-time analysis. Furthermore, this study investigates the accuracy of gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) in measuring the concentrations of glutathione and cysteamine. Additionally, the potential of new nanotechnology-based methods, such as plasmonic nanoparticles and quantum dots, to improve the sensitivity of detecting glutathione and cysteamine is emphasized., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Formaldehyde (HCHO) is a human toxin that is both a pollutant and endogenous metabolite. HCHO concentrations in human biological samples are reported in the micromolar range; however, accurate quantification is compromised by a paucity of sensitive analysis methods. To address this issue, we previously reported a novel SPME-GC-MS-based HCHO detection method using cysteamine as an HCHO scavenger. This method showed cysteamine to be a more efficient scavenger than the widely used O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine, and enabled detection of aqueous HCHO in the nanomolar range and quantification in the micromolar range. However, quantification in this range required immersive extraction of the HCHO-derived thiazolidine, while a high background signal was also observed. Following on from these studies, we now report an optimised head-space extraction SPME-GC-MS method using cysteamine, which provides similarly sensitive HCHO quantification to the immersive method but avoids extensive wash steps and is therefore more amenable to screening applications. However, high background HCHO levels were still observed A Complementary GC-MS analyses using a 2-aza-Cope-based HCHO scavenger also revealed high background HCHO levels; therefore, the combined results suggest that HCHO exists in high (i.e. micromolar) concentration in aqueous samples that precludes accurate quantification below the micromolar range. This observation has important implications for ongoing HCHO quantification studies in water, including in biological samples., (© 2024. The Author(s).)

In this study, a novel dextrin-based micelle (OSAD-SH), dual-modified with octenyl succinic anhydride (OSA) and cysteamine, was developed to address the acid instability issues of micelle modified only by OSA and designed for curcumin delivery. Three amphiphilic OSAD-SH polymers with different free sulfhydryl content were first synthesized. The study demonstrated that OSAD-SH micelles exhibited strong self-assembly properties, appearing as spheres with diameters ranging from 92.41 to 194.20 nm. Blank micelles showed good dilution resistance, as well as stability against acid, thermal, and ionic strength. The curcumin encapsulated by the micelles was in an amorphous state. In vitro release experiment demonstrated that curcumin released from OSAD-SH micelles exhibited pH responsiveness. The Ritger-Peppas model effectively predicted the release behavior of curcumin, which followed a super case-II transport. The OSAD-SH micelle will be a promising nanocarrier for improving the physicochemical properties of curcumin in food fields., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)

The disrupted oxidative redox homeostasis plays a critical role in the progress of ulcerative colitis (UC). Herein, hydrogel-forming viscous liquid (HSD) composed of cysteamine-grafted hyaluronic acid (HS) and superoxide dismutase (SOD) has been designed for UC. When the viscous HSD liquid was infused into colitis colon, SOD would convert the pathological superoxide (O 2 ·- ) to hydrogen peroxides (H 2 O 2 ), which was subsequently scavenged by HS. Accordingly, the sol-gel transition of HSD was initiated by scavenging H 2 O 2 , enhancing its adhesion toward colitis colon. H 2 O 2 -treated HSD presented the higher storage modulus and stronger adhesion force toward porcine colon than the untreated HSD. Besides, H 2 O 2 -treated HSD presented the slower erosion profile in the colitis-mimicking medium (pH 3-5), while its rapid degradation was displayed in physiologic condition (pH7.4). The combination of pH-resistant erosion and ROS-responsive adhesion for HSD rendered it with the specifical retention on the inflamed colonic mucosa of DSS-induced colitis mice. Rectally administrating HSD could effectively hinder the body weight loss, reduce the disease activity index and improve the colonic shorting of DSS-induced colitis mice. Moreover, the pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) were substantially decreased, the colonic epitheliums were well rearranged and the tight junction proteins were greatly recovered after HSD treatment. Besides, HSD also modulated the gut flora, markedly augmenting the abundance of Firmicutes, Barnesiella and Lachnospiraceae. Moreover, HSD treatment could regulate oxidative redox homeostasis via activating Nrf2-HO-1 pathway to reduce ROS and malondialdehyde and upregulate antioxidant enzymes (SOD, GPx and GSH). Collectively, HSD might be a promising therapy for UC treatments. STATEMENT OF SIGNIFICANCE: Herein, a hydrogel-forming viscous liquid (HSD) was designed by cysteamine-grafted hyaluronic acid (HS) and superoxide dismutase (SOD) for UC treatments. When the viscous HSD liquid was infused into a colitis colon, SOD would convert the pathological superoxide to hydrogen peroxides (H2O2), which was subsequently scavenged by HS. Accordingly, the sol-gel transition of HSD was initiated by scavenging H2O2, enhancing its adhesion to the colitis colon. The colonic epitheliums of DSS-induced colitis mice were well rearranged and the tight junction proteins (Zonula-1 and Claudin-5) were greatly recovered after the HSD treatment. Moreover, the HSD treatment could regulate oxidative redox homeostasis via activating the Nrf2-HO-1 pathway to reduce ROS and malondialdehyde and upregulate antioxidant enzymes (SOD, GPx and GSH)., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Metal nanoclusters (NCs) as a new kind of luminophore have acquired sufficient interest, but their widespread application is restricted on account of their relatively low electrochemiluminescence (ECL) efficiency. Then, aqueous metal NCs with high ECL efficiency were strongly anticipated, especially for the ultrasensitive analysis of biomarkers. Herein, a near-infrared (NIR) ECL biosensing strategy for the test of neuron-specific enolase (NSE) was proposed by utilizing N -acetyl-l-cysteine (NAC)- and cysteamine (Cys)-stabilized gold NCs (NAC/Cys-AuNCs) as ECL emitters with the NIR ECL emission around 860 nm and a metal-organic framework/palladium nanocubes (ZIF-67/PdNCs) hybrid as the coreaction accelerator through their admirable electrocatalytic activity. The NIR emission would reduce photochemical injury to the samples and even realize nondestructive analysis with highly strong susceptibility and suitability. Furthermore, the utilization of ZIF-67/PdNCs could improve the ECL response of NAC/Cys-AuNCs by facilitating the oxidation of the coreactant triethylamine (TEA), leading to the production of a larger quantity of reducing intermediate radical TEA •+ . Consequently, NAC/Cys-AuNCs with ZIF-67/PdNCs displayed 2.7 fold enhanced ECL emission compared with the single NAC/Cys-AuNCs using TEA as the coreactant. In addition, HWRGWVC (HWR), a heptapeptide, was introduced to immobilize antibodies for the specially binding Fc fragment of the antibodies, which improved the binding efficiency and sensitivity. As a result, a "signal-on" immunosensor for NSE analysis was obtained with an extensive linear range of 0.1 to 5 ng/mL and a low limit of detection (0.033 fg/mL) (S/N = 3). This study provides a wonderful method for the development of an efficient nondestructive immunoassay.

A cysteamine functionalized nanodiamond (NDC) was conjugated to gold nanoparticles (AuNPs) to deliver NDC@AuNPs and utilized in enhanced colorimetric detection of Cr 3+ at pH 6 environment. The conjugation was validated using FTIR, TEM, PXRD, DLS, and zeta potential investigations. At pH 6, superior sensory response of NDC@AuNPs to Cr 3+ than that of other ions was validated by UV-vis spectroscopy and colorimetric photographs. Results from UV-vis titrations displayed a linear regression from 0.01 to 0.4 µM with a LOD of 0.236 ± 0.005 nM. The particle aggregation, size variations, potential changes, and binding modes are investigated using TEM, DLS, and FTIR techniques to explore the underlying mechanisms. By adding the EDTA, sensory response is reversible up to 4 cycles. Finally, spiked real water experiments show improved sensing of Cr 3+ at pH 6 via the observed recovery between 96 and 110 %, which is in good agreement with the ICP-mass data., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

The objective of the investigation was to determine the ocular biodistribution of cysteamine, a reducing agent used for treatment of cystine crystals in cystinosis, following topical administration of a sustained release formulation and traditional eyedrop formulation. To the right eye only, rabbits received a 50 µL drop of 0.44% cysteamine eyedrops at one drop per waking hour for 2, 6, 12, and 24 h. A second group received one 100 µL drop of a sustained release formulation containing encapsulated cysteamine microspheres suspended in a thermoresponsive gel. Upon serial sacrifice, ocular tissues from both eyes and plasma were obtained and quantified for cysteamine using LC-MS/MS. Cysteamine was detected in the cornea, aqueous humor and vitreous humor. Systemic plasma concentrations of cysteamine from treatment groups were below the limit of detection. As expected, 0.44% cysteamine eyedrops when administered hourly maintained drug concentrations within the cornea at a magnitude 5 times higher than a single dose of the sustained release formulation over 12 h. The sustained release formulation maintained cysteamine presentation across 12 h from a single drop. These studies demonstrate distribution of cysteamine to the eye following topical administration, including high drug uptake to the cornea and low systemic distribution., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Currently, several biosensors are reported to confirm the absence/presence of an abnormal level of specific human biomarkers in research laboratories. Unfortunately, public marketing and/or pharmacy accessibility are not yet possible for many bodily fluid biomarkers. The questions are numerous, starting from the preparation of the substrates, the wet/dry form of recognizing the (bio)ligands, the exposure time, and the choice of the running buffers. In this context, for the first time, the present overview summarizes the pre-functionalization of standard and nanostructured solid/flexible supports with cysteamine (Cys) and glutaraldehyde (GA) chemicals for robust protein immobilization and detection of biomarkers in body fluids (serum, saliva, and urine) using three transductions: piezoelectrical, electrochemical, and optical, respectively. Thus, the reader can easily access and compare step-by-step conjugate protocols published over the past 10 years. In conclusion, Cys/GA chemistry seems widely used for electrochemical sensing applications with different types of recorded signals, either current, potential, or impedance. On the other hand, piezoelectric detection via quartz crystal microbalance (QCM) and optical detection by surface plasmon resonance (LSPR)/surface-enhanced Raman spectroscopy (SERS) are ultrasensitive platforms and very good candidates for the miniaturization of medical devices in the near future., Competing Interests: The author declares no conflict of interest.

In this study, we presented elective, sensitive, and rapid UV-Vis spectrophotometry and calorimetric assay for the recognition of digoxin. Therefore, cysteamine-gold nanoparticles (Cys A-AuNPs) in the presence of cysteine acid amine and Silver nanoparticles in the presence of tetramethyl benzidine and hydrogen peroxide (AgNPs-TMB [3,3',5,5'-tetramethylbenzidine]-H 2 O 2 ) were synthesized and utilized as the desired probe. Finally, color variation of probes was observed in the absence and presence of digoxin. Obtained results indicate that the color of Cys A-AuNPs changed from dark pink to light in the absence and the presence of digoxin, respectively. Also, the color of AgNPs-TMB-H 2 O 2 changed from dark blue to light blue, in the absence and the presence of digoxin, respectively. Moreover, UV-Vis spectroscopies results indicate digoxin with a low limit of quantification of 0.125 ppm in human plasma samples which linear range was 0.125 to 11 ppm., (© 2021 John Wiley & Sons Ltd.)

The complex pathogenesis of Alzheimer's disease (AD) calls for multi-target approach for disease treatment. Herein, based on the MTDLs strategy, a series of phthalimide-(N-alkylbenzylamine) cysteamide hybrids were designed, synthesized, and investigated in vitro for the purpose. Most of the target compounds were found to be potential multi-target agents. In vitro results showed that compound 9e was the representative compound in this series, endowed with high EeAChE and HuAChE inhibitory potency (IC 50  = 1.55 µm and 2.23 µm, respectively), good inhibitory activity against self-induced Aβ 1-42 aggregation (36.08% at 25 µm), and moderate antioxidant capacity (ORAC-FL value was 0.68 Trolox equivalents). Molecular docking studies rationalized the binding mode of 9e in both PAS and CAS of AChE. Moreover, 9e displayed excellent ability to against H 2 O 2 -induced PC12 cell injury and penetrate BBB. Overall, these results highlighted that compound 9e was an effective and promising multi-target agent for further anti-AD drug development., (© 2021 John Wiley & Sons A/S.)

In this study, a nanodrug carrier (mesoporous silica nanoparticle (MSN)-SS-cysteamine hydrochloride (CS)-hyaluronic acid (HA)) for targeted drug delivery was prepared using MSNs, in which HA was used as a targeting ligand and blocking agent to control drug release. Coumarin is a fluorescent molecule that targets mitochondria. Two conjugates (XDS-DJ and 5-FUA-4C-XDS) were synthesized by chemically coupling nitrogen mustard and 5-fluorouracil with coumarin, which was further loaded into MSN-SS-CS-HA nanocarriers. MTT analysis demonstrated that the nanocomposite MSN-SS-CS@5-FUA-4C-XDS/HA displayed stronger cytotoxicity toward HCT-116 cells than HeLa or QSG-7701 cells. Furthermore, MSN-SS-CS@5-FUA-4C-XDS/HA was able to target the mitochondria of HCT-116 cells, causing decreased mitochondrial membrane potential and excessive production of reactive oxygen species. These results indicate that MSN-SS-CS@5-FUA-4C-XDS/HA has the potential to be a nanodrug delivery system for the treatment of colon cancer., (© 2021 IOP Publishing Ltd.)

Parkinson's disease (PD) is characterized mainly by the loss of dopaminergic neurons in the substantia nigra (SN) mediated via oxidative stress. Although glutaredoxin-1 (GLRX1) is known as one of the antioxidants involved in cell survival, the effects of GLRX1 on PD are still unclear. In this study, we investigated whether cell-permeable PEP-1-GLRX1 inhibits dopaminergic neuronal cell death induced by 1-methyl-4-phenylpyridinium (MPP + ) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We showed that PEP-1-GLRX1 protects cell death and DNA damage in MPP + -exposed SH-SY5Y cells via the inhibition of MAPK, Akt, and NF-κB activation and the regulation of apoptosis-related protein expression. Furthermore, we found that PEP-1-GLRX1 was delivered to the SN via the blood-brain barrier (BBB) and reduced the loss of dopaminergic neurons in the MPTP-induced PD model. These results indicate that PEP-1-GLRX1 markedly inhibited the loss of dopaminergic neurons in MPP + - and MPTP-induced cytotoxicity, suggesting that this fusion protein may represent a novel therapeutic agent against PD.

Analogs of dirchromone were prepared to shed light on the pivotal role of its peculiar vinylsulfoxide side chain towards its cytotoxic and antimicrobial properties, especially dependant upon the presence and oxidation state of sulfur. The reaction of dirchromone with cysteamine revealed a surprising Michael acceptor behavior with elimination of the methylsulfinyl moiety and redox transformation of the sulfur atom that could be involved in the mode of action of dirchromone within cells.

α-Methylene-γ-lactones are present in ∼3% of known natural products, and compounds comprising this motif display a range of biological activities. However, this reactive lactone limits informed structure-activity relationships for these bioactive molecules. Herein, we describe chemically tuning the electrophilicity of the α-methylene-γ-lactone by replacement with an α-methylene-γ-lactam. Guaianolide analogues having α-methylene-γ-lactams are synthesized using the allenic Pauson-Khand reaction. Substitution of the lactam nitrogen with electronically different groups affords diverse thiol reactivity. Cellular NF-κB inhibition assays for these lactams were benchmarked against parthenolide and a synthetic α-methylene-γ-lactone showing a positive correlation between thiol reactivity and bioactivity. Cytotoxicity assays show good correlation at the outer limits of thiol reactivity but less so for compounds with intermediate reactivity. A La assay to detect reactive molecules by nuclear magnetic resonance and mass spectrometry peptide sequencing assays with the La antigen protein demonstrate that lactam analogues with muted nonspecific thiol reactivities constitute a better electrophile for rational chemical probe and therapeutic molecule design.

Human monoamine oxidases (MAOs) play important roles in maintaining the homeostasis of biogenic amines. One of its isoforms, monoamine oxidase B (MAOB), is thought to be involved in several neurodegenerative diseases, which make the selective detection of MAOB activity essential. In this work, a novel surface-enhanced Raman scattering (SERS) sensor was fabricated and the MAOB activity was specifically determined by detecting the SERS signals of an enzyme-catalyzed reaction product via an amine-aldehyde click reaction. This process was simply achieved by coating core-shell gold-silver nanoparticles (Au@Ag NPs) on 3-aminopropyl aminopropyl triethoxysilane (APTES)-modified glass, and then, a monolayer of cysteamine (CA) was attached to the nanoparticle surface as a linker through Ag-S bonds. Using phenethylamine (PA) as a specific substrate of MAOB, the enzyme product phenylacetaldehyde (PAA) will produce significant Raman signals via the amine-aldehyde click reaction with CA, while other molecules, such as MAOB and PA, have no signal output because they cannot form close interaction with nanoparticles due to the existence of a CA layer. This sensor was further used for the specific determination of MAOB activity in clinical blood samples and the MAOB inhibitor assessment successfully. Meanwhile, by changing the click reaction types and taking advantage of the SERS fingerprint peaks for the specific click reaction products, this strategy offers huge potential to detect multiple enzyme activities simultaneously and can be used for new click reaction screening, enzyme-related disease diagnosis, drug screening, and clinical diagnosis.

The carrot plant (Daucus carota ) and its components are traditionally reported for the management of gastric ulcers. This study was performed to evaluate the role of carrot when administered concurrently with a conventional antiulcer treatment, pantoprazole, in alleviating gastric and duodenal ulcers in female experimental animals. The study involved standard animal models to determine the ulcer preventive effect using pylorus ligation, ethanol, and stress induced acute gastric ulcer models and duodenal ulcer models involving cysteamine. Acetic acid-induced chronic gastric ulcer and indomethacin-induced gastric ulcer models were used to evaluate the ulcer healing effect. Carrot fruit (500 mg/kg) and its co-administration with pantoprazole produced significant protection in an ethanol- and stress-induced acute gastric ulcer and cysteamine-induced duodenal ulcer. The healing of the acetic acid-induced chronic gastric ulcer was also augmented with this combination. Both total proteins and mucin contents were significantly increased in indomethacin-induced gastric ulcers. Similarly, in pylorus ligation, the pepsin content of gastric juice, total acidity, and free acidity were reduced. Overall, both ulcer preventive effects and ulcer healing properties of the pantoprazole were significantly enhanced in animals who received the co-administration of carrot fruit (500 mg/kg).

A "turn-on" fluorescence sensor was developed for total detection of fumonisin B 1 , B 2 and B 3 (FB 1 , FB 2 and FB 3 ) in maize samples. Rhodamine B isothiocyanate (RBITC) and gold nanoparticles (AuNPs) were employed as the energy donor-acceptor pairs. The intensity of restored fluorescence was inversely proportional to the concentration of the FBs. The limit of detection (LOD) of the sensor for FB 1 was 23.80 pg/mL. The coefficient of variation (CV) was both less than 7% for intra- and inter-assay. The linear range was from 51.39 to 2125.92 pg/mL. The average recoveries of FBs from maize samples were ranged from 88.7% to 107.2%. The correlation coefficient of the results between the developed sensor and LC-MS/MS was 0.9970. To fulfill the procedure of the assay, only 46 min was needed. These results suggest that the fluorescence "turn-on" sensor has great potential applications in the analysis of FBs in maize samples., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The mechanism of hair loss caused by aging is related to mitochondrial dysfunction. Pep-1-mediated mitochondrial transplantation is a potential therapeutic application for mitochondrial disorders, but its efficacy against hair aging remains unknown. This study compared platelet-rich plasma (PRP) therapy with mitochondrial transplantation for hair restoration and examined the related regulation in naturally aging mice. After dorsal hair removal, 100-week-old mice received weekly unilateral injections of 200 μg of allogeneic mitochondria-labeled 5-bromo-2'-deoxyuridine with (P-Mito) or without Pep-1 conjugation (Mito) or human PRP with a stamp-type electric injector for 1 month. The contralateral sides were used as corresponding sham controls. Compared with the control and corresponding sham groups, all treatments stimulated hair regrowth, and the effectiveness of P-Mito was equal to that of PRP. However, histology revealed that only P-Mito maintained hair length until day 28 and yielded more anagen follicles with abundant dermal collagen equivalent to that of the PRP group. Mitochondrial transplantation increased the thickness of subcutaneous fat compared with the control and PRP groups, and only P-Mito consistently increased mitochondria in the subcutaneous muscle and mitochondrial DNA copies in the skin layer. Therefore, P-Mito had a higher penetrating capacity than Mito did. Moreover, P-Mito treatment was as effective as PRP treatment in comprehensively reducing the expression of aging-associated gene markers, such as IGF1R and MRPS5, and increasing antiaging Klotho gene expression. This study validated the efficacy of mitochondrial therapy in the restoration of aging-related hair loss and demonstrated the distinct effects of PRP treatment., (Copyright © 2020 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

The design of biomimetic model complexes for the cysteine dioxygenase (CDO) and cysteamine dioxygenase (ADO) is reported, where the 3-His coordination of the iron ion is simulated by three pyrazole donors of a trispyrazolyl borate ligand (Tp) and protected cysteine and cysteamine represent substrate ligands. It is found that the replacement of phenyl groups-attached at the 3-positions of the pyrazole units in a previous model-by mesityl residues has massive consequences, as the latter arrange to a more spacious reaction pocket. Thus, the reaction with O 2 proceeds much faster and afterwards the first structural characterization of an iron(II) η 2 -O,O-sulfinate product became possible. If one of the three Tp-mesityl groups is placed in the 5-position, an even larger reaction pocket results, which leads to yet faster rates and accumulation of a reaction intermediate at low temperatures, as shown by UV/Vis and Mössbauer spectroscopy. After comparison with the results of investigations on the cobalt analogues this intermediate is tentatively assigned to an iron(III) superoxide species., (© 2020 The Authors. Published by Wiley-VCH GmbH.)

Herein, a novel strategy for in situ imaging and real-time monitoring of intracellular tissue transglutaminase (TG2) is presented based on aggregation-induced emission (AIE). It has high sensitivity and specificity, minimal background signal and can also effectively distinguish different cell types (drug-resistant cancer cells, cancer cells and normal cells).

The thiolysis of B-type proanthocyanidins in cocoa by cysteamine was evaluated and optimized for its application in cocoa proanthocyanidin quantification. Four thiolysis products consisting of epicatechin, catechin, and their thioethers formed with cysteamine were separated and characterized by reversed-phase UPLC with photo diode array (PDA) detection and high-resolution mass spectrometry (HRMS). A thiolysis time of 20 min under 60 °C temperature was determined as the optimal condition for cocoa proanthocyanidin depolymerization. The optimized thiolysis condition was applied to four cocoa bean samples for proanthocyanidin quantification, using commercially available procyanidin B2 dimer as a reference standard. Satisfactory linearity and quantification and detection limits were achieved for the calibration curves, and proanthocyanidin contents determined by thiolysis were found to be higher than those determined by a published method based on normal-phase HPLC with fluorescence detection. Results in this study suggest promising application potential of cysteamine as an odorless thiolysis agent in routine quantitative analysis of B-type proanthocyanidins. Graphical abstract.

In this paper the innovative approach of nano into micro dry powders (NiM) was applied to incorporate into mannitol or mannitol/cysteamine micromatrices ivacaftor-loaded nanoparticles for pulmonary delivery in CF. Nanoparticles composed by a mixture of two polyhydrohydroxyethtylaspartamide copolymers containing loaded with ivacaftor at 15.5% w/w were produced. The nanoparticles were incorporated into microparticles to obtain NiM that were fully characterized in terms of size, morphology, interactions with artificial Cf mucus (CF-AM) as well as for aerodynamic behaviour. Finally the activity of ivacaftor-containing NiM was evaluated by in vitro preliminary experiments. NiM at matrix composed by a mixture of mannitol:cysteamine showed greater ability to reduce CF-AM viscosity whereas that based on just mannitol showed better aerodynamic properties with a FPF of about 25%. All produced NiM showed very good cytocompatibility and the released ivacaftor was able to restore the chroride transport in vitro., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A urinary tract infection (UTI) is a recurrent infection that requires timely diagnosis and appropriate treatment. Conventional urinalysis methods are laborious and time-consuming, and lack sensitivity and specificity. In this context, photoluminescence (PL)-based biosensors have gained more attention due to their fast response time, and enhanced sensitivity and specificity. In relation to this, a PL-based biosensor was developed using ZnO nanoparticles obtained via a microwave-assisted process functionalized with cysteamine (ZnO-Cys) to detect the quorum sensing signalling molecules of Gram-negative bacteria, N-acyl-homoserine lactones (AHLs). These AHLs are involved in bacterial communication and are responsible for activating virulence and pathogenicity. Biosensing measurements based on PL intensity variations corresponding to the O 2 acceptor defect level of ZnO with reference to ZnO-Cys were considered. A maximum sensitivity of 97% was achieved in the detection of AHL. The linear detection range of the developed biosensor was 10-120 nM in artificial urine media (AUM). The effect of pH on the sensitivity of the biosensor in AUM was also investigated and reported. The developed sensor was validated using the AHLs produced by Pseudomonas aeruginosa (MCC3101) in real-time analysis, which further confirmed the overall specificity and sensitivity.

The discrimination of cysteamine (CA) from mercapto amino acids (including glutathione, cysteine and homocysteine, GSH/Cys/Hcy) with high efficiency is essential to detect biothiols in a physiological environment. Herein, a nano-assembly was constructed by combining one-pot synthesized β-cyclodextrin-modified AuNPs and encapsulated rhodamine 6G (R6G-β-CD@AuNPs) without covalent modification. Interestingly, when the pH value of the tested solution was approximately the isoelectric point (pI) of the biothiol, the quenched fluorescence of R6G-β-CD@AuNPs was obviously restored by the introduction of the biothiol, which was due to the replacement of the R6G-β-CD composite by the biothiol on the surfaces of AuNPs via a stronger S-Au bond. The pI-mediated surface ligand exchange process was designed for the first time for the discrimination and detection of CA and GSH/Cys/Hcy at the pH values of 9.5 and 5.5, respectively. Under the optimized conditions, the enhanced fluorescence intensity displayed a good linear response to the concentration of each biothiol, with the detection limits of CA, GSH, Cys and Hcy calculated as 66.8, 417.6, 652.7 and 603.4 nM, respectively. The ingenious fabrication of the R6G-β-CD@AuNPs sensing platform eliminated the interferences from cholesterol by host-guest interactions and enabled high selectivity for the detection of biothiols in human serum samples. The pI-mediated sensing platform exhibits great potential for biothiol-related therapeutic drug monitoring.

Dynamic surface-enhanced Raman spectroscopy (D-SERS) was employed for the rapid detection of acephate in rice with simply regulated gold nanorods. Gold nanorods modified with cysteamine were prepared to circumvent the weak affinity of acephate molecules to the gold surface for a gigantic and stable enhancement. D-SERS was adopted to measure spectra of acephate residue at a range of 100.2-0.5 mg/L in rice samples, and the low residue of 0.5 mg/L can be still detected. Multivariant methods in machine or deep learning were used to develop the regression models for the automatic analysis of acephate residue level. Partial least squares regression and principal component analysis obtained the optimal performance with the root-mean-square error (RMSE) of validation of 5.4776, coefficient of determination (R 2 ) of validation of 0.9560, RMSE of prediction of 6.2845, and R 2 of prediction of 0.9541. Thus, the proposed method provides accurate and sensitive detection for acephate in rice., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Rare diseases usually concern small and disseminated population. Implementing clinical research with the right design, outcomes measures and the recruitment of patients are challenges. Collaborations, training and multidisciplinary approach are often required. In this article, we provide an overview of a successful collaboration in nephropathic cystinosis (NC), focusing on what was the key of success, the interactions between academics, the pharmaceutical company and patients organizations. NC is considered as a very rare disease. In 2010, a new formulation of cysteamine, the only available treatment to improve renal outcome of the disease, was proposed by a small American company. Studies were implemented in France under the coordination of an expert of the disease and the clinical investigation center of Lyon. The collaboration resulted in a good recruitment and retention of the patients in the study and most of all in the availability of the new formulation in France. Patients could have facilitated the research by being involved in the early stages of the studies. Involving patients and public early in the process is particularly important in rare diseases as the patient is a great source of knowledge and has his own expectations. Priorities of research, design, conduct and reporting of clinical trials can be defined in collaboration with adults but also with young patients or public, the first concerned in rare diseases. This concept is still to be developed and improved especially with paediatric patients., (Copyright © 2020. Published by Elsevier Masson SAS.)

A cysteamine functionalized core shelled nanoparticles (Au@Ag-CysNPs) was presented for simultaneous and rapid detection of sodium thiocyanate (STC) and benzoic acid (BA) preservatives in liquid milk using surface-enhanced Raman spectroscopy (SERS) technique. A spectrum covering 350-2350 cm -1 region was selected to detect STC with concentrations ranging from 0.5 to 10 mg/L and BA with concentrations ranging from 15 to 240 mg/L in milk samples. Characterization of nanoparticles using high-resolution TEM confirmed that the successful synthesis of Au@AgNPs with core (gold) size of 28 nm and shell (silver) thickness of about 5 nm was grafted with 120 μL of 0.1 nM cysteamine hydrochloride. Results showed that Au@Ag-CysNPs could be used to detect STC up to 0.03 mg/L with a limit of quantification (LOQ) of 0.039 mg/L and a coefficient of determination (R 2 ) of 0.9833 in the milk sample. For detecting BA, it could be screened up to 9.8 mg/L with LOQ of 10.2 mg/L and R 2 of 0.9903. The proposed substrate was also highly sensitive and the employed method involved only minor sample pretreatment steps. It is thus hoped that the new substrate could be used in the screening of prohibited chemicals in complex food matrices in future studies., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2018 Elsevier B.V. All rights reserved.)

While silver nanoparticles (AgNP) are used in topical treatments and medical devices for humans, no smooth, safe remedy exists to remove them and avoid possible post-treatment uptake in the body. We show here that cysteamine hydrochloride (CYS∙HCl), a simple FDA and EMA approved molecule, is able to dramatically accelerate the otherwise extremely slow oxidation of citrate-coated AgNP by O 2 in a wide range of pH, including the physiological 7.4 value, obtaining the halving of AgNP concentration in t < 10 min. The dependence of oxidation kinetics on CYS concentration and pH is studied, finding faster processes on increasing CYS and basicity, despite the decrease of O 2 reduction potential. Complexation and electrochemical studies demonstrate that CYS adhesion to AgNP surface followed by formation of 1:2 Ag + :CYS complex is the driving force for the AgNP oxidation, this also giving a definitive explanation to the otherwise still unclear phenomenon of AgNP etching by thiols. The efficacy of CYS∙HCl is verified also on AgNP coated with pectin and PEG-SH, and on AgNP immobilized on surfaces., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Cancer is one of the main causes of death worldwide. To decrease the mortality of cancer, early stage detection of cancer is of great importance. An innovative platform was developed for differentiation and detection of HT 29 cancer cells based on interactions between folate (FA) and folate receptors (FRs) of the membrane of cancer cells. In summary, FA and cysteamine (CA)-functionalized gold nanoparticles (AuNPs) were synthesized and characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and Fourier-transform infrared (IR) spectroscopy. Also, the surface charge was determined by measuring of the zeta potential. Fluorescence imaging and flow cytometry analyses were used to approve the selective uptake of the synthesized probe to the cancer cells. HEK 293 FR-negative cells were applied to assess the selectivity of AuNPs/CA/FA towards FR-negative cells. The differential pulse voltammetry (DPV) technique was used to determine the HT 29 cells from 250 to 5000 cells/mL with a lower limit of quantification (LLOQ) of 250 cells/mL. The produced AuNPs/CA/FA based nanoprobe could not only detect the signaling of HT 29 cells but also improve the specificity of cytosensor towards FR-positive cancer cells. According to the obtained results, the newly developed nano-probe could be used as a portable biomedical device for cancer diagnosis., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Donor-linker-acceptor (D-L-A)-based photoinduced electron transfer (PET) has been frequently used for the construction of versatile fluorescent chemo/biosensors. However, sophisticated and tedious processes are generally required for the synthesis of these probes, which leads to poor design flexibility. In this work, by exploiting a Schiff base as a linker unit, a covalently bound D-L-A system was established and subsequently utilized for the development of a PET sensor. Cysteamine (Cys) and N-acetyl-l-cysteine (NAC) costabilized gold nanoclusters (Cys/NAC-AuNCs) were synthesized and adopted as an electron acceptor, and pyridoxal phosphate (PLP) was selected as an electron donor. PLP can form a Schiff base (an aldimine) with the primary amino group of Cys/NAC-AuNC through its aldehyde group and thereby suppresses the fluorescence of Cys/NAC-AuNC. The Rehm-Weller formula results and a HOMO-LUMO orbital study revealed that a reductive PET mechanism is responsible for the observed fluorescence quenching. Since the pyridoxal (PL) produced by the acid phosphatase (ACP)-catalyzed cleavage of PLP has a weak interaction with Cys/NAC-AuNC, a novel turn-on fluorescent method for selective detection of ACP was successfully realized. To the best of our knowledge, this is the first example of the development of a covalently bound D-L-A system for fluorescent PET sensing of enzyme activity based on AuNC nanoprobes using a Schiff base.

Bimetallic gold core-silver shell (Au@Ag) surface-enhanced Raman scattering (SERS) tags draw broad interest in the fields of biological and environmental analysis. In reported tags, silver coating tended to smooth the surface and merge the original hotspot of Au cores, which was disadvantageous to signal enhancement from the aspect of surface topography. Herein, we developed gold nanorod (AuNR)-bridged Au@Ag SERS tags with uniform three-dimensional (3D) topography for the first time. This unique structure was achieved by selecting waxberry-like Au nanoparticles (NPs) as cores, which were capped by vertically oriented AuNR arrays. Upon selective surface blocking with thiol-ligands, Ag NPs were controlled to anisotropically grow on the tips of the AuNRs, producing high-density homo- (Ag-Ag) and hetero- (Au-Ag) hotspots in a single NP. The 3D hotspots rendered this NP extraordinary SERS enhancement ability (an analytical enhancement factor of 3.4 × 10 6 ) 30 times higher than the counterpart with a smooth surface, realizing signal detection from a single NP. More importantly, multiplexing signals ("blank" or multiplex "internal standard") can be achieved by simply changing thiol-ligands, as exemplified in the synthesis of NPs with 8 signatures. Furthermore, the multifunctionality has been demonstrated in living cell/in vivo imaging, photothermal therapy, and SERS substrates for ratiometric quantitative analysis, relying on the inherent internal standard signal. The prepared Au@Ag NPs have great potential as standard tools in many SERS-related fields.

The application of layer-by-layer (LbL) approach on nanoparticle surface coating improves the colon-specific drug delivery of insoluble drugs. Here, we aimed to formulate a self-assembled cysteamine-based disulphide cross-linked sodium alginate with LbL self-assembly to improve the delivery of paclitaxel (PCX) to colonic cancer cells. Cysteamine was conjugated to the backbone of oxidized SA to form a core of self-assembled disulphide cross-linked nanospheres. P3DL was selected for PCX loading and fabricated LbL with poly(allylamine hydrochloride) (PAH) and poly(4-styrenesulfonic acid-co-maleic acid) sodium salt (PSSCMA) resulting from characterization and drug release studies. P3DL-fabricated PCX-loaded nanospheres (P3DL/PAH/PSSCMA) exhibited an encapsulation efficiency of 77.1% with cumulative drug release of 45.1%. Dynamic light scattering analysis was reported at 173.6 ± 2.5 nm with polydispersity index of 0.394 ± 0.105 (zeta potential= -58.5 mV). P3DL/PAH/PSSCMA demonstrated a pH-dependent swelling transition; from pH 1 to 7 (102.2% increase). The size increased by 33.0% in reduction response study after incubating with 10 mM glutathione (day 7). HT-29 cells showed high viabilities (86.7%) after treatment with the fabricated nanospheres at 0.8 µg/mL. Cellular internalization was successful with more than 70.0% nanospheres detected in HT-29 cells. Therefore, this fabricated nanospheres may be considered as potential nanocarriers for colon cancer-targeted chemotherapeutic drug delivery.

Copper-cysteamine (Cu-Cy) is a novel sensitizer that can be excited by ultraviolet (UV) light, microwave (MW), ultrasound, and X-rays to generate highly toxic reactive oxygen species (ROS) for cancer cell destruction. The purpose of this study is to present a facile method for the synthesis of Cu-Cy nanoparticles. Interestingly, we were able to decrease both the stirring and heating time by about 24 and 6 times, respectively, thus making Cu-Cy nanoparticles more economical than what was reported before. 1,4-Diazabicylo[2.2.2]octane (DABCO), a well-known singlet oxygen quencher, showed that the majority of ROS produced by Cu-Cy nanoparticles upon UV and MW exposure were singlet oxygen. Moreover, ROS generated by Cu-Cy nanoparticles upon UV and MW exposure were confirmed by a known ROS tracking agent, dihydrorhodamine 123, further serving as an additional piece of evidence that Cu-Cy is a promising ROS generating agent to destroy cancer cells as well as bacteria or viruses by a radical therapeutic approach. Additionally, for the first time, the hydroxyl radical (˙OH) produced by Cu-Cy nanoparticles upon MW activation was proved by a photoluminescence (PL) technique using coumarin as a probe molecule. Remarkably, newly synthesized nanoparticles were found to be much more effective for producing ROS and killing cancer cells, suggesting that the new method may have increased the reactivity of the Cu-Cy nanoparticles due to an overall size reduction. Overall, the new method not only reduced the synthesis time but also enhanced the effectiveness of Cu-Cy nanoparticles for photodynamic therapy.

Stimuli responsivity has been extensively pursued in dynamic DNA nanotechnology, due to its incredible application potentials. Among diverse dynamic systems, redox-responsive DNA assembly holds great promise for broad applications, especially considering that redox processes widely exist in various physiological environments. However, only a few studies have been reported on redox-sensitive dynamic DNA assembly. Albeit ingenious, most of these studies are either dependent on the DNA sequence or involve chemical modification. Herein, a facile and universal mechanism to realize redox-responsive self-assembly of DNA nanocages (tetrahedron and cube) driven by the interconversion between cystamine and cysteamine toward dynamic DNA nanotechnology is reported., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The efficient identification of bacteria is of considerable significance in clinical diagnosis. Herein, a novel colorimetric sensor array was developed for the detection and identification of bacteria based on the specific affinity and electrostatic interaction between Wulff-type 4-mercaptophenylboronic acid (MPBA)-mercaptoethylamine (MA) cofunctionalized AgNPs (MPBA-MA@AgNPs) and bacteria at various pH. In the neutral and alkaline conditions, AgNPs tended to be dispersed due to the specific affinity between cis -diol residues contained in carbohydrate-rich compositions on the bacterial cell surface and MPBA. Bacterial cells have different carbohydrate compositions on their surface. The differential binding affinity of MPBA on the surface of AgNPs to cis -diol residues of various carbohydrates resulted in a different color change of AgNPs, which could be tuned by pH. On the contrary, AgNPs tended to be aggregated due to the electrostatic interaction between positively charged MA and negatively charged bacteria under acidic conditions. Therefore, using various pH buffer solutions as the sensing elements and MPBA-MA@AgNPs as the indicator, bacteria could be differentiated from each other by their own color response patterns. Moreover, the complex bacteria mixtures could be well discriminated. The method is simple, efficient, and visual and has a potential application in pathogen diagnosis.

Subunit vaccines are safer but often poorly immunogenic in comparison to traditional vaccines, and thus, adjuvants and delivery vehicles are needed to enhance the immune response. The complement system is a part of the innate immune system, which plays an important role in innate and adaptive immunity. Therefore, the activation of the complement system could be utilized as a potential strategy for vaccine applications. Herein, cysteamine hydrochloride was grafted onto a methoxy poly(ethylene glycol)- block- poly (allyl glycidyl ether)- block- poly(ε-caprolactone) copolymer to synthesize a triblock polymer mPEG 5k -PAGE15(NH 2 )-PCL 5k (TPCAH) with amino groups on the side chain. The positive charge of the amino groups could bind with the negatively charged protein (like ovalbumin (OVA)) to form a stable complex by electrostatic interaction. The triblock copolymer TPCAH we designed can easily self-assemble into polymer nanomicelles, and the size of the nanoparticles is similar to that of the pathogens, which was beneficial to the uptake by lymphocytes. Furthermore, the amino groups modified on the side chain can not only integrate with proteins but also activate the complement system, thereby enhancing the immune response of subunit vaccines. The results showed that the complex TPCAH@OVA could efficiently promote powerful anti-OVA-specific antibody production, enhance CD4 + T- and CD8 + T-cell activation, improve the lymphocyte proliferation efficiency, and increase the secretion of different cytokines. In addition, the abundant amino groups on the surface of TPCAH@OVA could effectively activate the complement system to further enhance adaptive immunity. Overall, these results indicated that the triblock copolymer TPCAH as an adjuvant and carrier can effectively improve the ability of innate and adaptive immune responses to resist pathogens, making it a potential candidate for vaccine applications.

A colorimetric method was developed for the determination of the mold toxin fumonisin B1 (FB1). It is based on the aggregation of cysteamine-capped gold nanoparticles (Cys-AuNPs). The assay involves alkaline hydrolysis of FB1 to obtain hydrolyzed fumonisin B1 (HFB1). The latter induces the aggregation of Cys-AuNPs which results in a color change from wine-red to blue-gray, best at a pH value of 9.0. A plot of absorbance ratio at 645/520 nm versus FB1 concentration is linear in the 2-8 μg kg -1 FB1 concentration range, and the detection limit is 0.90 μg kg -1 . Inter-day and intra-day precisions are <6.2%, and recoveries from spiked samples ranged from 93 to 99%. The assay was successfully applied to the determination of FB1 in corn samples. It has a high selectivity over other competitive mycotoxins including aflatoxin, zearalenone, citrinin and patulin. The method is more selective than the detection of FB1 directly which may lead to false-positive errors. Graphical abstract Schematic representation of colorimetric assay of fumonisin B1 (FB1). FB1 was alkali-hydrolyzed and its product (hydrolyzed fumonisin B1) induces cysteamine-capped gold nanoparticles (Cys-AuNPs) via hydrogen bondings. The aggregation of Cys-AuNPs causes changes in color from wine-red to blue-gray.

Highly efficient enrichment of phosphopeptides in low abundance prior to mass spectrometry analysis is essential in phosphopeptidomics analysis. Herein, an affinity probe possessing both interactions of polyoxometalates (POMs) and hydrophilic interaction chromatography (HILIC) was facilely prepared. POMs and cysteamine hydrochloride-modified chitosan (CYECS) were assembled onto magnetic nanoparticles (MNPs) via a layer-by-layer approach. The developed MNPs-(POM/CYECS) material owned merits of large metal oxide surfaces, positive charge, and hydrophilicity as well as superparamagnetism. By combining with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), the prepared material was utilized for effective enrichment of phosphopeptides. High selectivity (mass ratio of β-casein and bovine serum albumin digests of 1:5000) and low detection limit (0.02 fmol) toward phosphopeptides were achieved. The recovery of phosphopeptides was measured to be 92.6%. The specific enrichment of phosphopeptides from complex samples (nonfat milk, human saliva, serum, and A549 cell lysate) with MNPs-(POM/CYECS) material further confirmed its bright prospects for isolation of phosphopeptides from biological samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)

A method is described for single-step detection of V. parahaemolyticus in seafood via aptamer-based SERS. A gold-coated polydimethylsiloxane (PDMS) film was used for the enhancement of Raman scattering. The Raman reporter 4-mercaptobenzoic acid was linked to aptamer modified gold nanoparticles (AuNPs) served as a signalling probe. The negatively charged signalling probe was assembled onto the cysteamine-modified Au-PDMS film through electrostatic adsorption. On addition of V. parahaemolyticus, it will be bound by the aptamer as a biorecognition element, and this leads to the dissociation of the signalling probe from the Au-PDMS film. Hence, the Raman signal (at 1592 cm -1 ) decreases. The assay has a wide linear response that covers the 1.2 × 10 2 to 1.2 × 10 6  cfu·mL -1  V. parahaemolyticus concentration range. The detection limit is 12 cfu·mL -1 . The method was successfully applied to the determination of V. parahaemolyticus in oyster and salmon samples. Graphical abstract Schematic presentation of a surface-enhanced Raman spectroscopic method for single step detection of Vibrio parahaemolyticus using gold coated polydimethylsiloxane as the active substrate and aptamer modified gold nanoparticles. This solid substrate simplified the analysis procedures and enhanced the sensitivity.

Purpose: Oxygen permeability or transmissibility is a crucial parameter for contact lenses to ensure that extended wear will not induce corneal hypoxia. This work tests a new method of using the oxidation of cysteamine, an oxygen-sensitive chemical, to quantify the oxygen transmissibility of current commercial contact lenses and contact lenses loaded with vitamin E., Methods: 3D printing was used to modify eye drop bottles and quartz cuvettes to create systems that allowed insertion of a contact lens in between the cysteamine solution and air. Both systems were exposed to atmospheric conditions where the only path of entry for oxygen was through the contact lens. The entering oxygen reacted with cysteamine, and the rate of cysteamine oxidation was measured using UV-vis spectrophotometry. The rate was then stoichiometrically related to oxygen transmissibility., Results: The eye drop method predicted transmissibility values within 9% of established, commercial values. The cuvette method predicted values within 10% of established values for silicone hydrogel lenses without any correction factor and within 11% for poly-hydroxyethyl-methacrylate lenses after correcting for oxygen entering the system. Incorporation of 20% (w/w) vitamin E into Acuvue® Oasys® lenses did not have a significant impact on the oxygen transmissibility., Conclusions: Both methods presented in this work can reliably measure oxygen transmissibility of contacts lenses or other materials. Further improvements in manufacturing could lead to improved accuracy and reliability, allowing wider use of this method for quantifying the oxygen transport in contact lenses.

Sulfur containing ion imprinted polymers (S-IIPs) were applied for the uptake of Hg(II) from aqueous solution. Cysteamine which was used as the ligand for Hg(II) complexation, was grafted along the epichlorohydrin crosslinked carboxylated carboxymethyl cellulose polymer chain through an amide reaction. The adsorption ability of S-IIPs towards Hg(II) was investigated by kinetic and isotherm models, which, corresponding, showed that the adsorption process followed a pseudo-second-order, fitted well with the Langmuir isotherm with a maximum adsorption capacity of 80 mg/g. Moreover, thermodynamic studies indicated an endothermic and spontaneous reaction with the tendency of an enhanced randomness at the surface of the S-IIPs with temperature increases. S-IIPs indicated a high degree of selectivity towards Hg(II) in the presence of Cu 2+ , Zn 2+ , Co 2+ , Pb 2+ and Cd 2+ . Furthermore, the efficiency of S-IIPs was also evaluated against real samples showing 86.78%, 91.88%, and 99.10% recovery for Hg(II) wastewater, ground water and tap water, respectively. In this study, the adsorbent was successfully regenerated for five cycles, which allows for their reuse without significant loss of initial adsorption capability., (Copyright © 2018. Published by Elsevier B.V.)

In this study, cysteamine-functionalized molybdenum disulfide quantum dots (MoS 2 QDs) were synthesized by a one-pot hydrothermal method. A range of techniques including of Thioflavin T and 8-Anilino-1-naphthalenesulfonic acid fluorescence assays, circular dichroism, and transmission electron microscope have been employed to determination the efficacy of MoS 2 QDs on the inhibition/reversion of fibrillation and hindering cytotoxicity induced by protofibrils and amyloid fibrils of bovine serum albumin (BSA). Results demonstrated that MoS 2 QDs could effectively inhibit the fibrillogenesis and destabilize preformed fibrils of BSA in a concentration-dependent manner. Cytotoxicity protection and imagine on Hela cells was investigated using the methyl thiazolyl tetrazolium (MTT) assay. It was found that MoS 2 QDs not only has good biocompatibility, low toxicity and good cell penetration, but also could effectively decrease the cytotoxicity caused by the formed fibrils of BSA. The results obtained in this work suggested the potential biological application of MoS 2 QDs in therapeutics and provided new insight into the design of multifunctional nanomaterials for amyloid-related diseases., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This work focused the implementation of FRET processes between CdTe quantum dots (QDs), acting as donors, and gold nanoparticles (AuNPs), behaving as acceptors, for the determination of several bioactive thiols such as captopril, glutathione, l-cysteine, thiomalic acid and coenzyme M. The surface chemistry of the QDs and AuNPs was adjusted with adequate capping ligands, i.e. mercaptopropionic acid and cysteamine, respectively, to guarantee the establishment of strong electrostatic interaction between them and promoting the formation of stable FRET assemblies. Under these circumstances the fluorescence emission of the QDs was completely suppressed by the AuNPs. The assayed target analytes were capable of disrupting the donor-acceptor assemblies yielding a concentration-related reversion of the FRET process and restoring QDs fluorescence emission. Distinct mechanisms, involving enhancing of the QDs quantum yield (QY), AuNPs agglomeration, nanoparticles detachment, etc., could be proposed to explain the referred FRET reversion. The developed approach assured good analytical working ranges and demonstrate adequate sensitivity for the assayed compounds, anticipating great prospective for implementing rapid, simple and reliable sensing methodologies for the monitoring of pharmaceutical, food and environmental species. However, selectivity could be a hindrance in the detection of these bioactive thiols in more complex matrices such as environmental and food samples. This problem could be circumvented through the employment of multivariate chemometric methods for the analysis and processing of whole fluorometric response. Moreover, the proposed methodology shows a great analytical versatility since it is possible to easily adapt the surface chemistry, of both QDs and AuNPs, to the chemical nature of the target analyte., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Monitoring the levels of pesticides on plant tissues is important for achieving effective protection of crops after application, as well as ensuring low levels of residues during harvest. In this study, a simple, rapid, and fieldable colorimetric method for detecting the pesticide glyphosate (Gly) on the plant tissues in situ using cysteamine-modified gold nanoparticles (AuNPs-Cys) has been developed. The aggregation of AuNPs-Cys in the presence of Gly results in a consequent color change from red to blue (or purple), which could be observed visually on the surface of plant tissues. With the naked eye, we successfully detected Gly spiked on the surface of spinach, apple, and corn leaves in situ. Further verification and quantification were achieved using surface-enhanced Raman spectroscopy (SERS) which uses AuNPs-Cys as the substrate. Moreover, application of this method was demonstrated through the evaluation of the Gly distribution on plant tissues which could greatly facilitate the development of precision agriculture technology.

A highly selective circular dichroism sensor based on cysteamine-capped cadmium sulfide quantum dots (Cys-CdS QDs) was successfully developed for the determination of Cu 2+ . Basically, the Cys-CdS QDs are not active in circular dichroism spectroscopy. However, the circular dichroism probe (DPA@Cys-CdS QDs) can be simply generated in situ by mixing achiral Cys-CdS QDs with D-penicillamine. The detection principle was based on measuring the circular dichroism signal change upon the addition of Cu 2+ . The strong CD signal of the DPA@Cys-CdS QDs dramatically decreased in the presence of Cu 2+ , while other cations did not result in any spectral changes. In addition, the degree of the CD signal decrease was linearly proportional to the concentration of Cu 2+ in the range of 0.50-2.25 μM (r 2  = 0.9919) with a detection limit of 0.34 μM. Furthermore, the proposed sensor was applied to detect Cu 2+ in drinking water samples with %recovery values of 102-114% and %RSD less than 6%., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Twenty-four pure fragrance ingredients of concern as potential skin sensitizers were previously subjected to degradation studies and evaluated using the high throughput with dansyl cysteamine (HTS-DCYA) method. The experimental results showed that two-thirds of the 24 fragrance ingredients underwent chemical degradation. In some cases, such degradation was accompanied by an increase in thio-reactivity. These results prompted us to investigate the reactivity of the same ingredients using the direct peptide reactivity assay (DPRA). In the present work, the 24 chemicals were subjected to forced degradation for 150 days, and evaluated with both DPRA and HTS-DCYA methods. At the end of the study, four and eight compounds remained non-reactive in the DPRA and DCYA assay, respectively. Coumarin, benzyl salicylate, benzyl cinnamate and hexyl cinnamal were found unreactive in both assays, while cinnamal, cinnamyl alcohol, hydroxycitronellal and lilial were found negative in the DCYA but positive in the DPRA method. The incongruity in reactivity of these four compounds was attributed to a possible role of pro-oxidants formed upon degradation, resulting in depletion of peptide without formation of apparent covalent adducts with the test chemical. To validate this hypothesis, the effect of hydrogen peroxide as model pro-oxidant on both lysine- and cysteine-heptapeptide depletion in the DPRA method was thus investigated. The obtained results showed little effect of oxidative conditions on lysine depletion, while cysteine depletion was significantly affected by concentrations above 1.1 mg/L of hydrogen peroxide. Overall, both in chemico methods confirmed chemical instability should be considered when assessing the skin sensitization potential of (un)known chemicals with alternative methods., (© 2018 John Wiley & Sons, Ltd.)