Synthesis of ionically imprinted Poly(Alylthiourea) in the presence of 1-(2-Pyridylazo)-2-Napthol (PAN) for preconcentration in magnetic dispersive solid phase of nickel ions in water and food samples.

In the present study, a magnetic ion-imprinted polymer based on n-allylthiourea in the presence of 1-(2-pyridylazo)-2-naphthol (MIIP-PAN) was synthesized, characterized, and applied in the preconcentration of nickel ions by dispersive magnetic solid phase extraction (DMSPE) with FAAS detection. For comparison, non-imprinted polymer (MNIP-PAN) and imprinted polymer without PAN were synthesized. The characterization of the polymers was performed by FT-IR, DRX, TEM, TGA, VSM, and BET. Selectivity studies were performed comparing the competitive adsorption of Ni2+ with other cations on MIIP-PAN and MNIP-PAN, achieving higher relative selectivity coefficients for MIIP-PAN than for MNIP-PAN and NIP. Under optimized conditions, the method provided a preconcentration factor of 76.70, detection limit of 0.25 µg/L and intra-day (2.06 - 2.33 %) and inter-day (1.82 - 4.90 %) precision. The developed method was applied to samples of water, teas, and chocolate powder, and its precision was evaluated through tests of recovery and analysis of certified materials.

Discovery of 2-Naphthol from the Leaves of Actephila merrilliana as a Natural Nematicide Candidate.

To identify natural nematicides that can replace chemical nematicides, 2-naphthol with high activity against Meloidogyne incognita was isolated from Actephila merrilliana. The nematicidal activity of 2-naphthol against M. incognita was 100% at 100 µg/mL with an EC50 value of 38.00 µg/mL. Moreover, 2-naphthol had a significant negative effect on egg incubation. 2-Naphthol effectively inhibited the invasion of M. incognita into crops in both a pot experiment and field trial. In addition, the structure-activity relationship indicated that the naphthalene ring and its ß-site hydroxyl group were the key pharmacophores for the nematicidal activity of 2-naphthol. Nematodes were stimulated by 2-naphthol to produce excessive reactive oxygen species, which may be the underlying mechanism of 2-naphthol nematicidal activity. A systemic evaluation of 2-naphthol in tomato plants demonstrated that 2-naphthol remained mainly fixed in the roots after being absorbed by the crop and was not transported to the stems or leaves. Thus, 2-naphthol can be developed as a natural nematicide candidate.

Comparative study on the removal of 1- naphthol and 2-naphthol by ferrate (VI): Kinetics, reaction mechanisms and theoretical calculations.

In this study, the oxidation of 1-naphthol (1-NAP) and 2-naphthol (2-NAP) by Fe(VI) was investigated. The impacts of operating factors were investigated through a series of kinetic experiments, including Fe(VI) dosages, pH and coexisting ions (Ca2+, Mg2+, Cu2+, Fe3+, Cl-, SO42-, NO3- and CO32-). Almost 100% elimination of both 1-NAP and 2-NAP could be achieved within 300 s at pH 9.0 and 25 °C. Cu2+ could significantly improve the degradation efficiency of 1-NAP and 2-NAP, but the impacts of other ions were negligible. The liquid chromatography-mass spectrometry was used to identify the transformation products of 1-NAP and 2-NAP in Fe(VI) system, and the degradation pathways were proposed accordingly. Electron transfer mediated polymerization reaction was the dominant transformation pathway in the elimination of NAP by Fe(VI) oxidation. After 300 s of oxidation, heptamers and hexamers were found as the final coupling products during the removal of 1-NAP and 2-NAP, respectively. Theoretical calculations demonstrated that the hydrogen abstraction and electron transfer reaction would easily occur at the hydroxyl groups of 1-NAP and 2-NAP, producing NAP phenoxy radicals for subsequent coupling reaction. Moreover, since the electron transfer reactions between Fe(VI) and NAP molecules were barrierless and could occur spontaneously, the theoretical calculation results also confirmed the priority of coupling reaction in Fe(VI) system. This work indicated that the Fe(VI) oxidation was an effective way for removing naphthol, which may help us understand the reaction mechanism between phenolic compounds with Fe(VI).

Photocurrent Generation and Polarity Switching in Electrochemical Cells through Light-induced Excited State Proton Transfer of Photoacids and Photobases.

Light is a common source of energy in sustainable technologies for photocurrent generation. To date, in such light-harvesting applications, the excited electrons generate the photocurrent. Here, we introduce a new mechanism for photocurrent generation that is based on excited state proton transfer (ESPT) of photoacids and photobases that can donate or accept a proton, respectively, but only after excitation. We show that the formed ions following ESPT can either serve as electron donors or acceptors with the electrodes, or modify the kinetics of mass transport across the diffuse layer, both resulting in photocurrent generation. We further show that control of the current polarity is obtained by switching the irradiation between the photoacid and the photobase. Our study represents a new approach in photoelectrochemistry by introducing ESPT processes, which can be further utilized in light-responsive energy production or energy storage.

Co-inducible Catabolism of 2-Naphthol Initiated by Hydroxylase CehC1C2 in Rhizobium sp. X9 Removed Its Ecotoxicity.

2-Naphthol, which originates from various industrial activities, is widely disseminated through the discharge of industrial wastewater and is, thus, harmful to the water ecosystem, agricultural production, and human health. In this study, the carbaryl degrading strain Rhizobium sp. X9 was proven to be able to degrade 2-naphthol and reduce its toxicity to rice (Oryza sativa) and Chlorella ellipsoidea. Two-component hydroxylase CehC1C2 is responsible for the initial step of degradation and generates 1,2-dihydroxynaphthalene, which is further degraded by the ceh cluster. The transcription of gene cluster cehC1C2 could be induced when both 2-naphthol and glucose were added. A bioinformatic analysis revealed that two transcriptional regulators, the inhibitor CehR2 and the activator CehR3, could be involved in this process. Our study elucidated the molecular mechanism of microbial degradation of 2-naphthol and provided an effective strategy for the in situ remediation of 2-naphthol contamination in the environment.

Organo-Vermiculites Modified by Aza-Containing Gemini Surfactants: Efficient Uptake of 2-Naphthol and Bromophenol Blue.

To explore the effect of spacer structure on the adsorption capability of organo-vermiculites (organo-Vts), a series of aza-containing gemini surfactants (5N, 7N and 8N) are applied to modify Na-vermiculite (Na-Vt). Large interlayer spacing, strong binding strength and high modifier availability are observed in organo-Vts, which endow them with superiority for the adsorption of 2-naphthol (2-NP) and bromophenol blue (BPB). The maximum adsorption capacities of 5N-Vt, 7N-Vt and 8N-Vt toward 2-NP/BPB are 142.08/364.49, 156.61/372.65 and 146.50/287.90 mg/g, respectively, with the adsorption processes well fit by the PSO model and Freundlich isotherm. The quicker adsorption equilibrium of 2-NP than BPB is due to the easier diffusion of smaller 2-NP molecules into the interlayer space of organo-Vts. Moreover, stable regeneration of 7N-Vt is verified, with feasibility in the binary-component system that is demonstrated. A combination of theoretical simulation and characterization is conducted to reveal the adsorption mechanism; the adsorption processes are mainly through partition processes, electrostatic interaction and functional interactions, in which the spacer structure affects the interlayer environment and adsorptive site distribution, whereas the adsorbate structure plays a role in the diffusion process and secondary intermolecular interactions. The results of this study demonstrate the versatile applicability of aza-based organo-Vts targeted at the removal of phenols and dyes as well as provide theoretical guidance for the structural optimization and mechanistic exploration of organo-Vt adsorbents.

Spectrofluorimetric-based approach to screen urine contamination in drinking water: A step toward the development of screening method for leptospirosis.

Hygiene hypothesis and sanitization are two important pivots of modern civilization. The drinking water should be free from urine and stool contamination. Coliform test is popular for understanding feces contamination. However, understanding urine contamination in drinking water is a difficult task. On the other hand, urine contamination can cause disease like leptospirosis. It occurs mainly in animals and infects humans through contaminated water, food, and soil and causes serious consequences. Rat urine is the most common source of such disease outbreaks. Further, sophisticated laboratories with high-end technologies may not be present at the site of disease outbreaks. In this context, we have proposed a spectrofluorimetric approach to screen urine contamination in water. The screening method can sense up to 156 nl/ml of rat urine.

Synthesis of reusable cyclodextrin polymers for removal of naphthol and naphthylamine from water.

As one group of important naphthalene derivatives, naphthol and naphthylamine are diffusely employed as dye intermediates. The presence of naphthol and naphthylamine in water systems may pose risks to the environment and public health due to their carcinogenicity. In this study, four mesoporous polymers prepared by ß-cyclodextrin derivatives and tetrafluoroterephthalonitrile were obtained and applied to adsorbing 1-naphthylamine, 2-naphthylamine, 1-naphthol, and 2-naphthol from water. The impact of adsorption time, initial concentration of naphthol and naphthylamine, and temperature on the adsorption efficiency of the four polymers were explored separately. The four polymers present fast adsorption kinetics toward naphthol and naphthylamine, attaining 93 ~ 100% of adsorption equilibrium uptake for 1-naphthol, 1-naphthylamine, 2-naphthylamine in 15 min, and 87 ~ 90% of equilibrium uptake for 2-naphthol in 15 min. The kinetics could be depicted well by the pseudo-second-order kinetic model. The adsorption isotherms of the four polymers toward naphthol and naphthylamine accord with the Redlich-Peterson or Sips model. The maximum adsorption capacities of 1-naphthylamine, 2-naphthylamine, 1-naphthol, and 2-naphthol are 189.9 mg/g, 82.8 mg/g, 137.7 mg/g, and 88.7 mg/g, respectively. The adsorption ratio increases fast with reducing the initial concentration of naphthol and naphthylamine, and the adsorption ratio of naphthol and naphthylamine in 5 mg/L can achieve over 95% in 25 °C. In addition, the four polymers can be effortlessly regenerated by a gentle and simple washing procedure with little reduction in performance. The adsorption performance of the four polymers toward the four naphthalene derivatives can be improved by increasing the adsorption temperature. In conclusion, the prepared ß-cyclodextrin polymers exhibit rapid water treatment in removing the four low-concentration naphthalene derivatives with convenient regeneration and good reusability.

Allergic contact dermatitis from dyes used in the temple of spectacles.

BACKGROUND: We observed an increasing number of patients who presented with facial or retro-auricular dermatitis after skin contact with plastic spectacles or plastic covered temples. OBJECTIVES: To identify the allergens in plastic spectacles that may cause allergic contact dermatitis. METHODS: All patients with suspected allergic contact dermatitis to eyewear were tested with Solvent Orange 60 (SO60), four additionally with Solvent Yellow 14 (SY14), and five with scrapings from their own spectacles. In one case, a chemical analysis of the spectacles was performed to uncover the causative allergen. RESULTS: Three patients were allergic to SO60, two patients to SY14, and two patients were allergic to both SO60 and SY14. CONCLUSION: Patients with suspected allergic contact dermatitis from spectacles should be tested with SO60 and SY14, and based on findings from previous reports, also with Solvent Red 179.

Transition-Metal-Free [3+2] Dehydration Cycloaddition of Donor-Acceptor Cyclopropanes With 2-Naphthols.

A Brønsted acid-catalyzed domino ring-opening cyclization transformation of donor-acceptor (D-A) cyclopropanes and 2-naphthols has been developed. This formal [3+2] cyclization reaction provided novel and efficient access to the naphthalene-fused cyclopentanes in the absence of any transition-metal catalysts or additives. This robust procedure was completed smoothly on a gram-scale to afford the corresponding product with comparable efficiency. Furthermore, the synthetic application of the prepared product has been demonstrated by its transformation into a variety of synthetically useful molecules.

The chemical compound 'Heatin' stimulates hypocotyl elongation and interferes with the Arabidopsis NIT1-subfamily of nitrilases.

Temperature passively affects biological processes involved in plant growth. Therefore, it is challenging to study the dedicated temperature signalling pathways that orchestrate thermomorphogenesis, a suite of elongation growth-based adaptations that enhance leaf-cooling capacity. We screened a chemical library for compounds that restored hypocotyl elongation in the pif4-2-deficient mutant background at warm temperature conditions in Arabidopsis thaliana to identify modulators of thermomorphogenesis. The small aromatic compound 'Heatin', containing 1-iminomethyl-2-naphthol as a pharmacophore, was selected as an enhancer of elongation growth. We show that ARABIDOPSIS ALDEHYDE OXIDASES redundantly contribute to Heatin-mediated hypocotyl elongation. Following a chemical proteomics approach, the members of the NITRILASE1-subfamily of auxin biosynthesis enzymes were identified among the molecular targets of Heatin. Our data reveal that nitrilases are involved in promotion of hypocotyl elongation in response to high temperature and Heatin-mediated hypocotyl elongation requires the NITRILASE1-subfamily members, NIT1 and NIT2. Heatin inhibits NIT1-subfamily enzymatic activity in vitro and the application of Heatin accordingly results in the accumulation of NIT1-subfamily substrate indole-3-acetonitrile in vivo. However, levels of the NIT1-subfamily product, bioactive auxin (indole-3-acetic acid), were also significantly increased. It is likely that the stimulation of hypocotyl elongation by Heatin might be independent of its observed interaction with NITRILASE1-subfamily members. However, nitrilases may contribute to the Heatin response by stimulating indole-3-acetic acid biosynthesis in an indirect way. Heatin and its functional analogues present novel chemical entities for studying auxin biology.

Recent development in the synthesis of heterocycles by 2-naphthol-based multicomponent reactions.

2-Naphthol or ß-naphthol is an important starting material that has drawn great attention in various organic transformations because of its attributes, such as low cost, easy to handle and eco-friendliness. The electron-rich aromatic framework of 2-naphthol with multiple reactive sites allows it to be utilized in several kinds of organic reactions eventuated to several organic molecules with potent biological properties. Multicomponent reaction approach has been tremendously utilized to explore the synthetic utility of 2-naphthol for the construction of diverse N/O-containing heterocyclic framework. In this review, we summarize recent data pertaining to multicomponent reactions, wherein heterocyclic compounds are synthesized utilizing 2-naphthol as one of the starting materials. It is anticipated that this review will stimulate the researchers to design new multicomponent strategies complying with the Green Chemistry principles for the further exploitation of 2-naphthol for the rapid synthesis of versatile biologically relevant heterocycles. This review provides a concise overview of the different 2-naphthol based multicomponent reactions utilized for the construction of diverse bioactive heterocyclic scaffold.

Highly Effective Synthesis of 1-thioamidoalkyl-2-naphthols and Tetrahydropyridines Using a Nanostructured Silica-based Catalyst Under Mild Conditions.

AIM AND OBJECTIVE: Nano-2-[N',N'-dimethyl-N'-(silica-n-propyl)ethanaminium chloride]- N,N-dimethylaminium bisulfate (nano-[DSPECDA][HSO4]) was used as a highly effective and heterogeneous silica-based nanostructured catalyst for the synthesis of 1-thioamidoalkyl-2-- naphthols and substituted tetrahydropyridines. MATERIAL AND METHODS: The expected products were prepared in mild conditions. In this work, three novel 1-thioamidoalkyl-2-naphthols and two new tetrahydropyridine derivatives were synthesized and characterized by IR, 1H and 13C NMR and Mass spectroscopy. RESULTS: One-pot multi-component condensation of 2-naphthol with arylaldehydes and thioacetamide catalyzed by nano-[DSPECDA][HSO4] under green, mild and solvent-free conditions led to 1-thioamidoalkyl-2-naphthols in high yields. The nanocatalyst was also used for the preparation of functionalized tetrahydropyridines by the one-pot multi-component reaction of anilines, arylaldehydes and ethylacetoacetate under solvent-free and mild conditions. CONCLUSION: The reaction results were found to be better compared to the literature in terms of one or more of these factors: yield, time, and the reaction media. All the products were purified by recrystallization from EtOH, and without column chromatography, being in good agreement with the green chemistry protocols.

Association of Urinary Polycyclic Aromatic Hydrocarbons and Diabetes in Korean Adults: Data from the Korean National Environmental Health Survey Cycle 2 (2012-2014).

PURPOSE: To investigate the associations between the urinary levels of polycyclic aromatic hydrocarbons (PAHs) and diabetes mellitus in Korean adults. MATERIALS AND METHODS: We examined the data of 6478 participants aged ≥19 years from the Korean National Environmental Health Survey (KoNEHS) cycle 2 (2012-2014). The urinary levels of 1-hydroxypyrene (1-OHP), 2-naphthol (2-NAP), 1-hydroxyphenathrene (1-OHPhe), and 2-hydroxyfluorene (2-OHFlu) were measured by gas chromatography-mass spectrometry. Diabetes mellitus was defined as a self-report of physician-diagnosed diabetes mellitus or the use of oral hypoglycemics or insulin. Analyses were adjusted for sex, age, body mass index, household income, alcohol consumption, physical activity, urinary creatinine and cotinine, menopausal status, and quartiles of all other PAHs. RESULTS: The prevalence of diabetes was 6.5% in the study population. In men, the geometric means of the 2-NAP and 2-OHFlu levels were higher in participants with diabetes mellitus than in those without diabetes mellitus [4.11 vs 3.26 µg/L (P <0.05) and 0.45 vs 0.40 µg/L (P <0.05), respectively]. In women, the geometric mean of 2-NAP levels was also higher in participants with diabetes mellitus than in those without diabetes mellitus (1.81 vs 0.56 µg/L, P <0.05), but there were no significant differences in geometric means for other PAHs. A higher odds ratio (OR) of diabetes was found in participants with the highest quartiles of urinary 2-NAP [OR 1.83, 95% confidence interval (CI) 1.29-2.60] and 2-OHFlu (OR 1.81, 95% CI 1.10-2.98) than in those with the lowest quartiles. CONCLUSION: The urinary 2-NAP and 2-OHFlu levels were associated with diabetes mellitus in Korean adults. Further studies are needed to determine a potential causal relationship between PAH exposure and diabetes mellitus and its underlying mechanism.

N-doped mesoporous carbon as a new sorbent for ultrasonic-assisted dispersive micro-solid-phase extraction of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene, from urine samples.

This study aimed to optimize a new sample preparation method using N-doped mesoporous carbon sorbent for simultaneous measurement of 1-naphthol and 2-naphthol, the biomarkers of exposure to naphthalene. The samples were analyzed using high-performance liquid chromatography supplied with ultraviolet detector (HPLC-UV). N-doped mesoporous carbon sorbent was obtained via the hard template procedure. The synthesized nanosorbent was then characterized by transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), and elemental analysis (CHN). The effective factors in the extraction of the studied biomarkers were examined by the Box-Behnken (BBD) methodology. Regarding the optimum conditions, the sketched calibration curve for naphthols was linear in the concentration levels of 1-600 µg L-1 for human urine samples. The accuracy and reproducibility of the introduced method were determined using the relative recovery (RR %) and relative standard deviation (RSD %) tests on the fortified urine samples. RR% and RSD% were found to be 97.0-101.2% and 3.1-9.0%, respectively. The calculated method detection limit of the optimized procedure was 0.3 µg L-1 and 0.5 µg L-1 for 1-naphthol and 2-naphthol, respectively.

Cross-validation of biomonitoring methods for polycyclic aromatic hydrocarbon metabolites in human urine: Results from the formative phase of the Household Air Pollution Intervention Network (HAPIN) trial in India.

The Household Air Pollution Intervention Network (HAPIN) trial is evaluating health benefits of a liquefied petroleum gas (LPG) stove intervention in biomass cook-fuel using homes (n = 3200) in four low-and middle-income countries (LMICs) that include Peru, Guatemala, Rwanda and India. Longitudinal urine samples (n = 6000) collected from enrolled pregnant women, infants and older women will be analyzed for biomarkers associated with exposure and health outcomes. We report results from cross-validation of a lower cost high-performance liquid chromatography with fluorescence detection (HPLC-FLD) method with a higher resolution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the measurement of 1-hydroxypyrene (1PYR) and 2-naphthol (2NAP). Twenty-five split urine samples were analyzed by HPLC-FLD method at the India trial site in Chennai, India and by LC-MSMS method at the trial wide Biomarker Coordinating Center, Emory University, USA. The limits of detection (LOD) for the HPLC-FLD method were 0.02 ng/mL and 0.07 ng/mL for 2NAP and 1PYR, respectively. Bland-Altman analysis estimated a bias of 2.98 ng/ml for 2NAP (95% CI: -5.22, -0.75) and 0.09 ng/mL for 1PYR (95% CI: -0.02, 0.21) with HPLC-FLD levels being lower than LC-MSMS levels at higher concentrations. Analyses of additional urine samples (n = 119) collected during the formative phase of the HAPIN trial in India, showed 2NAP and 1PYR levels to be consistently above the limit of quantification (LOQ) and demonstrated the applicability of the method. The HPLC-FLD method can serve as a cost-effective and reliable analytical method to measure 2NAP and 1PYR in human urine in LMICs, within and beyond the HAPIN trial.

Determinação espectrofotométrica de Cobre(II) em aguardente de mandioca (Tiquira) / Spectrophotometric determination of Copper (II) in manioc spirit (Tiquira)

RESUMO A pesquisa descreve a reação espectrofotométrica do complexo Cu(II)-PAN (1-(2-piridilazo)-2-naftol) e determina a concentração de cobre (II) em aguardente de mandioca (Tiquira). Para isso, dimensionamos a reação para os estudos de absorção do complexo, pH, estabilidade, proporção estequiométrica, interferentes, correlação e recuperação. Após essa etapa, determinamos a concentração de cobre(II) em cinco amostras de bebidas destiladas artesanalmente de cinco municípios do Estado do Maranhão. O resultados mostram que o complexo absorve em 548 nm em pH 6, é estável em um tempo de 7 horas em proporções estequiométrica mínima de 1:1 do ligante e metal, possui limite de detecção em 3,3 X 10-2 mg L-1, faixa de linearidade de 1 X 10-6 a 1 X 10-5 mol L-1, correlação (R2= 0,9990), desvio padrão=0,0035 e recuperação em 104,54 ± 7,01 e os principais íons interferentes são o ferro (III) e o cobalto (II). Na aguardente, constatamos que o teor de cobre está acima do permitido pela legislação brasileira.

SUMMARY The search describes the spectrophotometric reaction of the Cu (II)-PAN (1-(2-pyridilazo) -2-naphthol) complex and determines the concentration of copper (II) in manioc spirit (Tiquira). For this, we dimensioned the reaction for the studies of complex absorption, pH, stability, stoichiometric ratio, interferences, correlation, and recovery. After this step, we determined the concentration of copper (II) in five samples of beverages distilled artisanal from five municipalities of the State of Maranhão. The results show that the complex absorbs at 548 nm at pH 6, is stable at a time of 7 hours in minimum 1:1 stoichiometric proportions of the binder and metal, has a detection limit in 3.3 X 10-2 mg L-1, range (R2= 0.9990), standard deviation= 0.0035 and recovery at 104.54 ± 7.0, and the main interfering ions are iron (III) and cobalt (II). In the brandy, we find that the copper content is above that allowed by Brazilian legislation.

Magnetic graphene/chitosan nanocomposite: A promising nano-adsorbent for the removal of 2-naphthol from aqueous solution and their kinetic studies.

In this study, magnetic/graphene/chitosan nanocomposite (MGCH) is prepared through facile solvothermal process and employed as an adsorbent for the removal of 2-naphthol from aqueous solution. The physico-chemical characteristic results of FESEM, Raman, FTIR, XRD and VSM confirms that the MGCH nanocomposite is effectively prepared. The FESEM and EDS analysis reveals that the high density of spherical-like Fe3O4 nanoparticles and chitosan are successfully assembled on the surfaces of the graphene sheets. VSM result of MGCH composite exhibited higher saturation magnetization of 46.5 emu g-1 and lower coercivity (Hc) of 50 Oe. This result discloses that MGCH possesses enough response required for the separation from aqueous solution. The batch mode adsorption studies demonstrates that MGCH based adsorbent showed almost 99.8% adsorption of 2-naphthol with a maximum adsorption capacity of 169.49 mg g-1 at pH 2. Moreover, the kinetic studies of the samples are performed by fitting adsorption models to ensure the nature of the adsorption system. This work proves that MGCH nanocomposite can be used as high-performance adsorbent for removing of phenolic pollutants from contaminated wastewater.

Development of a Reversible Indicator Displacement Assay Based on the 1-(2-Pyridylazo)-2-naphthol for Colorimetric Determination of Cysteine in Biological Samples and Its Application to Constructing the Paper Test Strips and a Molecular-Scale Set/Reset Memorized Device.

A new colorimetric chemosensor for naked-eye detection and determination of cysteine (Cys) based on indicator displacement assay (IDA) was designed using 1-(2-pyridylazo)-2-naphthol (PAN). The indicator exchange occurred between PAN and Cys by the addition of Cys to the Cu(PAN)2 complex, which is accomplished by an immediate visible color change from magenta to yellow, in the solution phase and paper-based test strips. The proposed method exhibits 0.35 µmol L-1 detection limit and good linearity in the range of 2.25-42.91 µmol L-1. Paper test strips presented a detection limit of 38.0 µmol L-1, fabricating an easy to use test kit for compatible "in-the-field" detection of Cys. The computer image analysis of the paper test strips, obtained from the CMYK color analysis system, showed a linear increase in Y (yellow) intensity with enhancement in the Cys concentration of 50.0-550.0 µmol L-1. Additionally, the absorption and color change obtained in this chemosensor operate as an "INHIBIT" logic gate considering Cu2+ and Cys as inputs. Eventually, based on such a fast, reversible, and reproducible signal, a molecular-scale sequential memory unit was designed displaying "Writing-Reading-Erasing-Reading" and "Multi-Write" behavior. The developed chemosensor presented a satisfactory repeatability, intermediate precision, and successful application for the selective determination of Cys in human biological fluids. Graphical abstract .

Drug delivery system of dual-responsive PF127 hydrogel with polysaccharide-based nano-conjugate for textile-based transdermal therapy.

Pluronic F-127 based dual-responsive (pH/temperature) hydrogel drug delivery system was developed involving polysaccharide-based nano-conjugate of hyaluronic acid and chitosan oligosaccharide lactate and applied for loading of gallic acid which is the principal component of traditional Chinese medicine Cortex Moutan recommended in the treatment of atopic dermatitis. The polysaccharide-based nano-conjugate was used as pH-responsive compound in the formulation and its amphiphilic character was determined colorimetrically. Microstructure analysis by SEM and TEM indicated highly porous hydrogel network and well-dispersed micellar structures, respectively, after modification with the nano-conjugate, and so, release property of the hydrogel for drug was significantly improved. Different pH-conditions were applied here to see pH-responsiveness of the formulation and increase in acidity of external environment gradually diminished mechanical stability of the hydrogel and that was reflected on the drug release property. Rheology was performed to observe sol-gel transition of the formulation and showed better rheological properties after modification with nano-conjugate. In this study, the cytotoxicity results of PF127 based formulations loaded with/without gallic acid showed cell viability of > 80.0 % for human HaCaT keratinocytes in the concentration range of 0.0-20.0 µg/ml.