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1.
Chemosphere ; 286(Pt 3): 131876, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34418657

RESUMO

Herein, sulfide-modified nanoscale zero-valent iron (S-nZVI) was prepared by a liquid-phase reduction route and then applied to activate persulfate (PS) for the degradation of chloramphenicol (CAP). The effects of Fe/S molar ratio, catalyst dosage, PS concentration, initial pH, and co-existing ions (Cl-, SO42-, CO32-) on the catalytic performance of S-nZVI/PS system were investigated. Simultaneously, the fluctuations of solution pH, oxidation-reduction potential, dissolved oxygen, and Fe2+ concentration were also monitored during the reaction. Results shown that 98.8 % of CAP could be removed under the optimum reaction conditions (S-nZVI dosage = 0.1 g/L, PS concentration = 3 mM, initial pH = 6.86). Compared to the pristine nZVI, the sulfidation behavior could critically improve the removal efficiency of CAP, ascribe to the enhancements of hydrophobicity of nZVI, production of hydroxyl radicals, and salt resistance. Furthermore, possible degradation pathways of CAP in S-nZVI/PS system were inferred based on liquid chromatography-mass spectrometry (LC-MS) and density functional theory (DFT) calculations. This study proves that the S-nZVI is a more promising catalyst for activating PS than nZVI, especially in the field of saline pharmaceutical wastewater treatment.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Cloranfenicol , Ferro , Sulfetos , Poluentes Químicos da Água/análise
2.
Chemosphere ; 286(Pt 3): 131943, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34426266

RESUMO

The wide use of chloramphenicol and its residues in the environments are an increasing threat to human beings. Electroactive microorganisms were proven with the ability of biodegradation of chloramphenicol, but the removal rate and efficiency need to be improved. In this study, a model electricigens, Geobacter metallireducens, was supplied with and Fe3O4 and MnO2 nanoparticles. Five times higher chloramphenicol removal rate (0.71 d-1) and two times higher chloramphenicol removal efficiency (100%) was achieved. Fe3O4 and MnO2 nanoparticles highly increased the current density and NADH-quinone oxidoreductase expression. Fe3O4 nanoparticles enhanced the expression of alcohol dehydrogenase and c-type cytochrome, while MnO2 nanoparticles increased the transcription of pyruvate dehydrogenase and Type IV pili assembly genes. Chloramphenicol was reduced to a type of dichlorination reducing product named CPD3 which is a benzene ring containing compound. Collectively, Fe3O4 and MnO2 nanoparticles increased the chloramphenicol removal capacity in MFCs by enhancing electron transfer efficiency. This study provides new enhancing strategies for the bioremediation of chloramphenicol in the environments.


Assuntos
Geobacter , Nanopartículas Metálicas , Cloranfenicol , Geobacter/genética , Humanos , Compostos de Manganês , Oxirredução , Óxidos
3.
Food Chem ; 366: 130648, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34325245

RESUMO

A novel label-free fluorescence aptasensor was established for chloramphenicol (CAP) detection by DNA four-arm junction-assisted target recycling and SYBR Green I dye-aided fluorescence-signal amplification. The CAP aptamer was hybridized to its complementary strand (primer) to form a double-stranded primer/aptamer complex. In the presence of CAP, aptamers can specifically bind with CAP to dissociate primers, which can trigger the self-assembly of four hairpins to continuously generate DNA four-arm junctions. After digesting the excess hairpins using T7 exonuclease, SYBR Green I was inserted into the base pair-rich DNA four-arm junctions, which led to a significant increase in fluorescence intensity. Under optimal conditions, the developed aptasensor can detect CAP in a linear range of 1.0 pg mL-1 to 10 ng mL-1 with a detection limit of 0.72 pg mL-1. The recovery rates in milk and honey ranged from 90.3% to 106.6%. Thus, the method shows substantial potential for CAP detection in food products.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Animais , Cloranfenicol/análise , DNA , Limite de Detecção , Leite/química
4.
Spectrochim Acta A Mol Biomol Spectrosc ; 264: 120264, 2022 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-34375837

RESUMO

An entropy driven catalytic reaction powered DNA motor was proposed for simultaneous detection of ochratoxin A (OTA) and chloramphenicol (CAP) in food. The dumbbell hairpin structure was formed by the two aptamers of OTA and CAP. The dumbbell hairpin can be opened by the interaction of OTA and CAP with their aptamers. The tails of the end of dumbbell hairpin sequence can induce the entropy driven catalytic reactions on the AuNPs, causing the sustained releasing of the fluorophore labeled DNA sequences. The recovery of fluorescent intensities can be used for quantitative detection of OTA and CAP. The limit of detection reached 2 pM for OTA and 6 pM for CAP respectively, which was great improved by entropy driven amplification of the self-powdered DNA motor. This strategy is simple and sensitive and only needs one-step operation. It exhibits promising potentiality in food quality control and food security supervision.


Assuntos
Aptâmeros de Nucleotídeos , Técnicas Biossensoriais , Nanopartículas Metálicas , Cloranfenicol , DNA , Entropia , Ouro , Limite de Detecção , Ocratoxinas
5.
Chemosphere ; 286(Pt 1): 131604, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34303905

RESUMO

The complexation mechanism between pharmaceuticals and natural colloids is still uncertain due to the complexity, heterogeneity, and polydispersity of colloids. Therefore, this study investigated the effect of fluorescence properties on the complexation of chloramphenicol (CAP) and carbamazepine (CBZ) to the colloids from Poyang Lake Basin based on the multiple spectroscopic techniques and methods. Three-dimensional excitation-emission matrix fluorescence spectroscopy-parallel factor analysis results illustrated that two humic-like components and two protein-like components of colloids from the rivers and lakes were identified, with the much higher fluorescence intensity of the protein-like substance observed in lake samples. The protein-like substance decreased dramatically with the addition of CAP and CBZ, suggesting its higher binding capacity towards these drugs, especially for CBZ. In addition, the fluorescence quenching titration was proceeded to explore the binding mechanism between the colloids and the pharmaceuticals. Results of synchronous fluorescence spectra and two-dimensional correlation spectroscopy demonstrated that the fluorescence quenching effect occurred preferentially between the protein-like substances and the pharmaceuticals, with the stronger complexation for CBZ. Ryan-Weber model fitting results showed that the stability constant ranged from 4.02 to 5.04 with the higher binding capacity observed for the tryptophan-like substance. Combined, the fluorescence components in aquatic colloids could be significantly impacted the complexation of the pharmaceuticals. This study provides deep insights into the fate and pollution protection of pharmaceuticals.


Assuntos
Carbamazepina , Cloranfenicol , Coloides , Substâncias Húmicas/análise , Rios , Espectrometria de Fluorescência
6.
Molecules ; 26(19)2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34641509

RESUMO

A dual recognition system with a fluorescence quenching of quantum dots (QDs) and specific recognition of molecularly imprinted polymer (MIP) for the detection of chloramphenicol (CAP) was constructed. MIP@SiO2@QDs was prepared by reverse microemulsion method with 3-aminopropyltriethoxysilane (APTS), tetraethyl orthosilicate (TEOS) and QDs being used as the functional monomer, cross-linker and signal sources, respectively. MIP can specifically recognize CAP, and the fluorescence of QDs can be quenched by CAP due to the photo-induced electron transfer reaction between CAP and QDs. Thus, a method for the trace detection of CAP based on MIP@SiO2@QDs fluorescence quenching was established. The fluorescence quenching efficiency of MIP@SiO2@QDs displayed a desirable linear response to the concentration of CAP in the range of 1.00~4.00 × 102 µmol × L-1, and the limit of detection was 0.35 µmol × L-1 (3σ, n = 9). Importantly, MIP@SiO2@QDs presented good detection selectivity owing to specific recognition for CAP, and was successfully applied to quantify CAP in lake water with the recovery ranging 102.0~104.0%, suggesting this method has the promising potential for the on-site detection of CAP in environmental waters.


Assuntos
Cloranfenicol/análise , Fluorometria/métodos , Pontos Quânticos/química , Compostos de Cádmio/química , Fluorescência , Concentração de Íons de Hidrogênio , Lagos/análise , Limite de Detecção , Microscopia Eletrônica de Transmissão , Impressão Molecular , Propilaminas/química , Sensibilidade e Especificidade , Silanos/química , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Telúrio/química , Poluentes Químicos da Água/análise
7.
Molecules ; 26(19)2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34641512

RESUMO

The improper use of antibiotics has led to the development of bacterial resistance, resulting in fewer antibiotics for many bacterial infections. Especially, the drug resistance of hospital-acquired methicillin-resistant Staphylococcus aureus (HA-MRSA) is distinctly serious. This research designed and synthesized two series of 3-substituted ocotillol derivatives in order to improve their anti-HA-MRSA potency and synergistic antibacterial activity. Among the synthesized compounds, 20-31 showed minimum inhibitory concentration (MIC) values of 1-64 µg/mL in vitro against HA-MRSA 18-19, 18-20, and S. aureus ATCC29213. Compound 21 showed the best antibacterial activity, with an MIC of 1 µg/mL and had synergistic inhibitory effects. The fractional inhibitory concentration index (FICI) value was 0.375, when combined with chloramphenicol (CHL) or kanamycin (KAN). The structure-activity relationships (SARs) of ocotillol-type derivatives were also summarized. Compound 21 has the potential to be developed as a novel antibacterial agent or potentiator against HA-MRSA.


Assuntos
Antibacterianos/síntese química , Antibacterianos/farmacologia , Ginsenosídeos/química , Cloranfenicol/farmacologia , Desenho de Fármacos , Sinergismo Farmacológico , Canamicina/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Staphylococcus aureus/efeitos dos fármacos , Relação Estrutura-Atividade
8.
Anal Chem ; 93(42): 14287-14292, 2021 10 26.
Artigo em Inglês | MEDLINE | ID: mdl-34637621

RESUMO

Sensitive and precise determination of chloramphenicol (CAP) is of great significance for human health due to its high risk in trace amounts. Solid-state artificial nanochannels are expected to be highly promising sensing devices owing to single-molecule sensitivity, target-specific selectivity, and portability. Herein, we report an aptamer self-assembly-functionalized artificial nanochannel-based sensor for highly sensitive and precise determination of CAP. Aptamer self-assembly (AAs) served as the specific recognition component and were in situ grown on the surface of stable anodic aluminum oxide (AAO) nanochannels to develop an AAs@AAO nanochannel-based sensor. Selective interaction with CAP led to the disassembly of AAs and sensitive current change of AAs@AAO nanochannels, allowing sensitive and precise sensing of CAP in complex food samples. The developed AAs@AAO nanochannel-based sensor showed a wide linear range from 0.32 to 1600 pg. mL-1, low limit of detection (LOD) of 0.1 pg. mL-1, high precision with relative standard deviation of 2.9%, and quantitative recoveries of 93.4-102.2% for CAP in milk, milk powder, and honey samples. This work proposes a versatile nanochannel-based platform for facile, sensitive, and precise sensing of hazardous residues in food samples.


Assuntos
Técnicas Biossensoriais , Mel , Animais , Cloranfenicol/análise , Eletrodos , Mel/análise , Humanos , Limite de Detecção , Leite/química
9.
Chemosphere ; 285: 131568, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34710968

RESUMO

Chloramphenicol (CAP) is widely used in daily life, and its abuse hurts human health, so a suitable method is needed to solve the problem. In this study, the Ti/PbO2 electrodes prepared by the electroplating method were characterized. The CAP degradation effect and mechanism were investigated. It was shown that the electrode surface had a dense plating with a characteristic peak of ß-PbO2 as the active component. The electrode had an oxygen precipitation potential of 1.695 V and a corrosion potential of 0.553 V, and a long service life (505.4 d). The degradation of CAP at Ti/PbO2 electrode followed a first-order kinetic reaction. The optimal degradation conditions (current density of 12.97 mA cm-2, electrolyte concentration of 50 mM, and solution pH of 6.38) were obtained by the response surface curve method. The degradation rate of CAP was 99.0% at 60 min. The results showed that the reactive groups leading to CAP degradation were mainly ·OH and SO42-, and only a tiny portion of CAP was directly oxidized on the electrode surface. The addition of Cl- favored the degradation of CAP, but reduced the mineralization rate. LC-MS analysis showed that ·OH mainly attacked the asymmetric centers (C1, C2) of weakly bound hydrogen atoms, resulting in underwent addition and substitution reactions. CAP was converted into two substances with m/z = 306 and m/z = 165. Finally, inorganic substances such as CO2 and H2O were generated. This study provided a new idea for preparing Ti/PbO2 electrode with high performance and the safe and efficient degradation of CAP.


Assuntos
Titânio , Poluentes Químicos da Água , Cloranfenicol , Eletrodos , Humanos , Óxidos , Poluentes Químicos da Água/análise
10.
Sheng Wu Gong Cheng Xue Bao ; 37(10): 3653-3662, 2021 Oct 25.
Artigo em Chinês | MEDLINE | ID: mdl-34708617

RESUMO

Microorganisms are the dominant players driving the degradation and transformation of chloramphenicol (CAP) in the environment. However, little bacterial strains are able to efficiently degrade and mineralize CAP, and the CAP degrading pathways mediated by oxidative reactions remain unclear. In this study, a highly efficient CAP-degrading microbial consortium, which mainly consists of Rhodococcus (relative abundance >70%), was obtained through an enrichment process using CAP-contaminated activated sludge as the inoculum. A bacterial strain CAP-2 capable of efficiently degrading CAP was isolated from the consortium and identified as Rhodococcus sp. by 16S rRNA gene analysis. Strain CAP-2 can efficiently degrade CAP under different nutrient conditions. Based on the biotransformation characteristics of the detected metabolite p-nitrobenzoic acid and the reported metabolites p-nitrobenzaldehyde and protocatechuate by strain CAP-2, a new oxidative pathway for the degradation of CAP was proposed. The side chain of CAP was oxidized and broken to generate p-nitrobenzaldehyde, which was further oxidized to p-nitrobenzoic acid. Strain CAP-2 can be used to further study the molecular mechanism of CAP catabolism, and has the potential to be used in in situ bioremediation of CAP-contaminated environment.


Assuntos
Cloranfenicol , Rhodococcus , Biodegradação Ambiental , RNA Ribossômico 16S/genética , Rhodococcus/genética , Esgotos
11.
Chem Commun (Camb) ; 57(71): 8989-8992, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34486607

RESUMO

We present the in situ formation of a hole-transporting material (bismuth hexacyanoferrate) on the surface of bismuth tungstate aimed at an innovative photoelectrochemical strategy. This approach enabled a competent aptasensing platform for chloramphenicol that was amenable to homogenous, label-free, and split-mode detection.


Assuntos
Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Bismuto/química , Técnicas Eletroquímicas/métodos , Compostos de Tungstênio/química , Animais , Cloranfenicol/análise , Cloranfenicol/química , Ferricianetos/química , Contaminação de Alimentos/análise , Lagos/análise , Limite de Detecção , Leite/química , Processos Fotoquímicos , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química
12.
Analyst ; 146(19): 5995-6004, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34505605

RESUMO

In this work, metal-organic frameworks (MOFs) are utilized as effective ECL coreactant accelerator to enhance the ECL responses of N-(aminobutyl)-N-(ethylisoluminol) (ABEI). Zn-based MOFs (MOF-Zn-1) were prepared by chelating Zn ions with melamine and thiophenedicarboxylic acid (TPDA), which observably accelerated the electrocatalytic oxidation of tripropylamine (TPA). Then, ABEI-MOF-Zn-1 as a high-performance ECL emitter was synthesized via an amide reaction between ABEI and mercaptopropionic acid (MPA) modified MOF-Zn-1. Strikingly, the ABEI-MOF-Zn-1 showed the 18-fold increase in the ECL signals relative to pure ABEI by using TPA as a coreactant. Moreover, ferrocene (Fc) as a quencher was first linked with capture DNA (cDNA), and then used to modify the ABEI-MOF-Zn-1, thereby constructing a label-free ECL biosensor. After the linkage between chloramphenicol (CAP) and aptamer DNA (aptDNA), the ECL response was definitely recovered by releasing L-DNA from double-stranded DNA (dsDNA, hybridization of aptDNA and L-DNA). The resultant sensor showed a wide linear range of 1.00 nM-0.10 mM (R2 = 0.99) and a low limit of detection (LOD) down to 0.11 nM for detecting CAP. This work developed a novel pattern to design an efficient ECL enhanced emitter, coupled by expanding its potential applications in clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Estruturas Metalorgânicas , Cloranfenicol , Técnicas Eletroquímicas , Limite de Detecção , Medições Luminescentes
13.
Water Sci Technol ; 84(3): 512-523, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34388116

RESUMO

Antibiotic residues may be very harmful in aquatic environments, because of limited treatment efficiency of traditional treatment methods. An electrochemical system with a Ti-based SnO2-Sb-Ni anode was developed to degrade a typical antibiotic chloramphenicol (CAP) in water. The electrode was prepared using a sol-gel method. The performance of electrode materials, impact factors and dynamic characteristics were evaluated. The Ti-based SnO2-Sb-Ni electrode was compact and uniform as shown by characterization using SEM and XRD. The electrocatalytic oxidation of CAP was carried out in a single-chamber reactor by using a Ti-based SnO2-Sb-Ni electrode. For 100 mg L-1 CAP, the CAP removal ratio of 100% and the TOC removal ratio of 60% were obtained at the current density of 20 mA cm-2 and in a neutral electrolyte at 300 min. Kinetic investigation has shown that the electro-oxidation of CAP on a Ti-based SnO2-Sb-Ni electrode displayed a pseudo-first-order kinetic model. Free radical quenching experiments presented that the oxidation of CAP on Ti-based SnO2-Sb-Ni electrode resulted from the synergistic effect of direct oxidation and indirect oxidation (·OH and ·SO4-). Doping Ni on the Ti/SnO2-Sb electrode for CAP degradation was presented in this paper, showing its great application potential in the area of antibiotic and halogenated organic pollutant degradation.


Assuntos
Titânio , Poluentes Químicos da Água , Cloranfenicol , Eletrodos , Oxirredução , Compostos de Estanho
14.
Water Sci Technol ; 84(3): 524-537, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34388117

RESUMO

In this study, the aim was to explore the effectiveness of the UV/H2O2 photolysis (UVP) process in terms of antimicrobial activity reduction and increasing the mean oxidation number of carbon (MONC) under the degradation of chloramphenicol (CHPL) drug. CHPL degradation kinetics and the effects of foreign anions on CHPL degradation were explored in this study. The order of the inhibition effect was found as Cl- > NO3- > HCO3- due to their different in HO• radical scavenging capacity. A pseudo-first-order model for CHPL degradation was well established, and the rate constant (kobs) was 2.93 × 10-2 min-1 (R2 = 0.98) in UVP. Thirteen intermediate products were detected in MS-chromatogram and were identified through different proposed degradation pathways. The cleavage of the amide side chain in CHPL was more effective in CHPL degradation due to an electrophilic attacks by HO. radicals on it. The inactivation rates of E. coli were decreased due to the reduction of -NO2 group into -NH2 functional group in CHPL that leads to the production of low toxic compounds on CHPL degradation.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Antibacterianos , Cloranfenicol , Escherichia coli , Peróxido de Hidrogênio , Cinética , Oxirredução , Fotólise , Raios Ultravioleta , Poluentes Químicos da Água/análise
15.
Artigo em Inglês | MEDLINE | ID: mdl-34444558

RESUMO

Chloramphenicol has been used in veterinary medicine, where its residues can remain in food of animal origin, thus potentially causing adverse health effects. This facilitated the ban for its use in food-producing animals globally, but its residues have remained ubiquitous. In this study, food commodities possibly contaminated with chloramphenicol, including livestock meat, poultry, edible viscera, fish, shrimp and crab, molluscs, milk, and eggs, were collected from domestic retail shops in all the 11 districts of Guangzhou and tested for its residue. Probabilistic risk assessment model calculations for its dietary exposure, and the margin of exposure (displayed as mean values and 5th percentile to 95th percentile ranges) were performed by using @RISK software based on a Monte Carlo simulation with 10,000 iterations. The results indicated the detection of chloramphenicol in 248 out of 1454 samples (17.1%), which averaged to a level of 29.1 µg/kg. The highest average value was observed in molluscs (148.2 µg/kg, with the top value as 8196 µg/kg); meanwhile, based on the dietary structure of a typical Cantonese, pond fish, pork, and poultry meat contributed most (about 80%) to the residents' dietary exposure to chloramphenicol. The margin of exposure for dietary chloramphenicol exposure in Guangzhou residents was 2489, which was apparently below 5000 (the borderline for judging a health risk), particularly low in preschool children (2094, suggesting an increased risk). In conclusion, the study suggests that chloramphenicol exposure in Guangzhou residents is considerable, and its relevant health hazard, especially for preschool children, is worthy of further investigation.


Assuntos
Cloranfenicol , Exposição Dietética , Animais , China , Cloranfenicol/toxicidade , Exposição Dietética/análise , Contaminação de Alimentos/análise , Medição de Risco
16.
J Org Chem ; 86(17): 11557-11570, 2021 09 03.
Artigo em Inglês | MEDLINE | ID: mdl-34387504

RESUMO

A unified strategy for an efficient and high diastereo- and enantioselective synthesis of (-)-chloramphenicol, (-)-azidamphenicol, (+)-thiamphenicol, and (+)-florfenicol based on a key catalytic syn-selective Henry reaction is reported. The stereochemistry of the ligand-enabled copper(II)-catalyzed aryl aldehyde Henry reaction of nitroethanol was first explored to forge a challenging syn-2-amino-1,3-diol structure unit with vicinal stereocenters with excellent stereocontrol. Multistep continuous flow manipulations were carried out to achieve the efficient asymmetric synthesis of this family of amphenicol antibiotics.


Assuntos
Tianfenicol , Antibacterianos , Catálise , Cloranfenicol/análogos & derivados , Compostos Heterocíclicos com 3 Anéis , Nitrocompostos , Tianfenicol/análogos & derivados
17.
Water Environ Res ; 93(11): 2716-2726, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34415641

RESUMO

The PbO2 -2 wt.% sodium dodecyl sulfate composite formed from methanesulfonate electrolyte consists of 93.1% of α-phase PbO2 in contrast to the similar one synthesized from nitrate electrolyte, which contains 73.3% of ß phase. The electrocatalytic activity of the obtained composites in the oxygen evolution reaction and oxidation of chloramphenicol was investigated. It was found that the Tafel slope significantly exceeds the theoretical value, which indicates a decrease in the degree of filling of the electrode surface with oxygen-containing particles. In the presence of organic compound and chloride ions in the solution, irreversible adsorption of the intermediate is observed, which leads to additional blocking of active centers on the oxide surface, which are involved in the oxidation of organic substance. It was established that the maximum rate of chloramphenicol conversion is 83.5% and 85% at 50 and 80 mA cm-2 , respectively, under kinetic control. The heterogeneous oxidation rate constant of chloramphenicol is 0.0035 min-1 . Oxidation of chloramphenicol occurs through the formation of 4-(-2-amino-1,3-dihydroxy-propanyl)-nitrobenzene with cleavage of dichloroacetic acid. Next, the amino group is oxidized to the nitro group to form 4-(2-nitro-1,3-dihydroxy-propanyl)-nitrobenzene. Subsequent electrolysis produces nitrobenzoic acid, which is oxidized to benzoic acid, later hydroquinone, then benzoquinone and a set of aliphatic compounds. PRACTITIONER POINTS: The PbO2 -2 wt.% SDS composite consists of 93.1% of α phase of PbO2 in contrast to those synthesized from nitrate electrolyte. The Tafel slope indicates a decrease of surface filling with oxygen-containing particles. Irreversible adsorption of the intermediate is observed in the presence of chloride ions.


Assuntos
Cloranfenicol , Poluentes Químicos da Água , Eletrodos , Chumbo , Oxirredução , Óxidos , Tensoativos , Titânio , Poluentes Químicos da Água/análise
18.
ACS Appl Mater Interfaces ; 13(30): 35689-35699, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34289693

RESUMO

Stimuli-responsiveness is an important characteristic that show promising potential in various applications. Herein, a novel ZIF-8-on-Tb-dpn (H3dpn = 5-(2',4'-dicarboxylphenyl)nicotic acid) heterostructure is constructed using a heteroepitaxial strategy combining the chemical-responsive (antibiotics) and light-responsive behaviors. The pyridine nitrogen of Tb-dpn acts as an anchor site for Zn2+, which helps to overcome the limit of lattice mismatch between two metal-organic frameworks (MOFs) and promotes the growth of ZIF-8 nanocrystals. Based on the synergy effect of two MOFs, ZIF-8-on-Tb-dpn exhibits an efficient turn-off response toward tetracycline and chloramphenicol via competitive absorption, Förster resonance energy transfer, and photoinduced electron transfer processes with limit of detection values of 5.6 and 37.6 nM, respectively, which are three- to -fivefold lower than those of Tb-dpn. Moreover, the nanocage of ZIF-8 is utilized to encapsulate photochromic spiropyran (SP) molecules and realize the reversible conversion between SP and merocyanine (MC) under visible light and ultraviolet light. The MC form is accompanied with strong adsorption at 555 nm, which can erase the emission of Tb3+. Therefore, a reversible invisible anticounterfeiting pattern is designed with SP ⊂ ZIF-8-on-Tb-dpn for information anticounterfeiting. The excellent stimuli-responsive ability makes the luminescent platform a potential candidate in luminescence applications.


Assuntos
Antibacterianos/análise , Fraude/prevenção & controle , Substâncias Luminescentes/química , Estruturas Metalorgânicas/química , Adsorção , Antibacterianos/química , Cloranfenicol/análise , Cloranfenicol/química , Indóis/química , Indóis/efeitos da radiação , Isomerismo , Compostos de Espiro/química , Compostos de Espiro/efeitos da radiação , Tetraciclina/análise , Tetraciclina/química , Raios Ultravioleta
19.
Luminescence ; 36(7): 1767-1774, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34270836

RESUMO

In this study, nitrobenzene was used as dummy template to synthesize a type of specific molecularly imprinted microspheres for chloramphenicol, and 4-nitroaniline was coupled with three fluorophores to synthesize three fluorescent tracers. Then a competitive fluorescence method was developed on a conventional microplate for detection of chloramphenicol in chicken and pork samples. This method contained only one sample-loading step, so one assay was finished within 30 min. The IC50 was 1.8 ng/ml, and the limit of detection was 0.06 ng/g. The recoveries from chloramphenicol-fortified blank meat samples were in the range 67.5-96.2%. Furthermore, this method could be recycled three times. The detection results for some real meat samples were identical to that of a LC-MS/MS method. Therefore, this method could be used as a practical tool for routine screening for the residue of chloramphenicol in large number of meat samples.


Assuntos
Cloranfenicol , Impressão Molecular , Cloranfenicol/análise , Cromatografia Líquida , Carne/análise , Microesferas , Espectrometria de Massas em Tandem
20.
Int J Pharm ; 606: 120897, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34293473

RESUMO

Melt electrospinning of polylactide (PLA) loaded with chloramphenicol (CAM) has been performed and characteristics of fibers, physical properties of scaffolds, CAM release behavior, antibacterial properties and biocompatibility have been evaluated. The interest of CAM loaded samples is nowadays enhanced for biomedical applications since this antibiotic has been demonstrated to be efficient for the treatment of cancer. Melt electrospinning has been selected as an ideal preparation process because it avoids the use of toxic solvents which are harmful to the environment and could be problematic for biomedical applications. The electrospinning process rendered fibers with a relatively large diameter (between 20 µm and 40 µm depending on the load) and minimum polymer degradation. Characteristics of melt electrospun scaffolds were also compared with those prepared by solution electrospinning. Differences consisted in a more sustained release and a higher biocompatibility for the melt processed samples. Bactericide effect was evaluated as an evidence of the maintenance of the CAM bioactivity after melt processing at high temperature and the slower release caused by the relatively high diameter of the constitutive fibers. Since pure CAM showed thermal degradation at temperatures relatively close to the PLA melting temperature, a complete analysis of the degradation process of pure CAM as well as of PLA samples loaded with CAM was performed. The Invariant Kinetic Parameters method allowed determining an initial decomposition step that followed an autoaccelatory Avrami model, and then an autocatalytic decomposition reaction took place for conversions higher than 50%. Dispersion in the PLA matrix enhances the thermal stability of the antibiotic, with an onset temperature of degradation that was higher by 16 °C in the melt-electrospun fibers than in the liquid state of pure CAM.


Assuntos
Cloranfenicol , Poliésteres , Antibacterianos , Polímeros
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