Chloramphenicol Research Articles

Antibiotic Chloramphenicol degradation using submerged thermal plasma synergized with LaMnO3 catalyst

The present study focused on the degradation of antibiotic Chloramphenicol (CAP), an emerging contaminant, using submerged thermal plasma (STP) technology. Almost 99 % degradation and 82 % mineralization were achieved within 20 min of treatment by Ar/CO2 plasma, generated at 6.2 kW discharge power using a customized thermal plasma torch inside the aqueous solution. Kinetic analysis revealed first-order reaction for CAP degradation with a rate constant of 0.257 min−1. Long-lived species, such as H2O2, O3, NO2–, NO3–, and Cl- formed during plasma treatment were quantified. LaMnO3 perovskite (LMO) nanopowder prepared through a novel thermal plasma route, was introduced as catalyst into the treatment system which enhanced the degradation and mineralization efficiency by 34 % and 17 %, respectively, showing a strong synergetic effect between STP and catalyst. The energy yield was elevated from 102 mg/kWh to 144 mg/kWh with the addition of catalyst into the STP treatment system. Liquid chromatography-mass spectroscopy was used to identify the various degradation intermediates produced during thermal plasma treatment and correspondingly possible degradation pathways were proposed. The antibacterial activity assessment results revealed a significant reduction in the antimicrobial activity of all treated solutions against Gram-positive Bacillus cereus and Gram-negative Pseudomonas aeruginosa bacteria. Additionally, seed germination and growth assessment revealed a reduction in phytotoxicity of the treated solutions. STP, combined with the LMO, proved highly effective in treating pharmaceutical contamination in aqueous medium.

Formulating biomolecular crowns on micelles: A potential strategy for improving micelle stability

The complex environment in blood circulation has a tremendous destabilizing effect on the micelles structure, which is a vital issue to be addressed in micelles design and application. Biomolecule crowns, quickly formed on the surface of nanocarriers in vivo, may alter the physicochemical properties of nanocarriers. In this study, bovine serum albumin (BSA) or fetal bovine serum (FBS) was formulated as the biomolecular crown of the bacterial lipase-responsive micelles encapsulating the hydrophobic antibiotics chloramphenicol (CHL) to investigate their stabilization effect on the micelles. Compared with BSA-crowned micelles (BSA/PM@CHL), FBS-crowned micelles (FBS/PM@CHL) reduced drug leakage by more than 90 % without masking their lipase responsiveness, it also inhibited 77 % of bacterial growth in in vitro antibacterial activity study and significantly increased the area under plasma concentration curve and in vivo half-life in pharmacokinetic study. Then the Förster resonance energy transfer (Fret) Effect was used to further explore the mechanisms responsible for the differences between the BSA-crown and FBS-crown. The in vitro anti-dilution tests below the critical micellar concentration showed that FBS-crown could improve the thermodynamic stability of the micelles, the micelle integrity of FBS/PM was 2 times higher than that of PM diluted with aqueous dilution and 6.5 times higher than that diluted with rat plasma dilution. In vivo optical imaging study showed that micelles with dual-labeled FBS/PM (mean value = 0.363) maintained better structural integrity than dual-labeled PM (mean value = 0.325) after 4 h of injection, explaining the ability of FBS-crowned micelles to improve pharmacokinetic parameters in terms of thermodynamic stability. Besides, the destruction of PM integrity slowed down after injection into the blood circulation for 4–8h, indicating that the baring of biomolecular-crown may be in the late cycle. Overall, the biomolecular-crowned micelles strategy presents a promising strategy for maintaining the structural and functional stability of micelles under physiological conditions.

HSPiP and QbD oriented optimized green nanoemulsion to treat chloramphenicol contaminated water

Nanoemulsion is an isotropic and kinetically stable system used for multiple purposes. Exhaustive flow of chloramphenicol (CAMP) in the water systems raised global thereat to aquatic and human lives. Innate cohesive energy of the material is the basis of predictive HSPiP program. We aimed to prepare biocompatible nanoemulsion employing eugenol oil, lecithin, tween 80, and propylene glycol) for the contaminated water treatment. Furthermore, experimental design oriented robust nanoemulsion (OCEN1) investigated the impact of composition, CTime (exposure time), and nanoemulsion characteristics on percent removal efficiency (%RE). Thermodynamic stability study was conducted at different temperatures. Finally, the presence of CAMP in the treated water was negated by ICP-OES (inductively coupled plasma-optical emission spectroscopy). HSP (Hansen solubility parameters) and experimental solubility data were the basis of excipient selection. A blend of tween-80 and lecithin served as surfactant mixture (Smix) to stabilize nanoemulsion. OCEN1 was associated with high desirability (D = 0.93), low size (43 nm), low PDI (0.19), high %RE (90.72 % over period of 17 min of exposure time), optimal viscosity (1.12 cP), and high zeta potential (−25 mV). Experimental design identified significant impact of composition, exposure time (CTime), and nanoemulsion characteristics on %RE as prime factors to consider before wastewater treatment plant installation. Thus, the approach is simple, rapid, ecofriendly, and scalable to treat CAMP contaminated water with high selectivity and efficiency.

Ultrasensitive Ti3C2Tx@Pt-Based Immunochromatography with Catalytic Amplification and a Dual Signal for the Detection of Chloramphenicol in Animal-Derived Foods.

Herein, a catalytic amplification enhanced dual-signal immunochromatographic assay (ICA) based on Pt nanoparticles (Pt NPs) modified with Ti3C2Tx MXene (Ti3C2Tx@Pt) was first developed for chloramphenicol (CAP) in animal-derived foods. Due to the large specific surface area and abundant active sites of Ti3C2Tx@Pt, they can be loaded with hundreds of Pt NPs to enhance their catalytic activity, resulting in a significant increase in the detection sensitivity; the sensitivity was up to 50-fold more sensitive than the reported ICA for CAP. The LODs of the developed method for milk/chicken/fish were 0.01 μg/kg, the LOQs were 0.03 μg/kg and the recovery rates were 80.5-117.0%, 87.2-118.1% and 92.7-117.9%, with corresponding variations ranging from 3.1 to 9.6%, 6.0 to 12.7% and 6.0 to 13.6%, respectively. The linear range was 0.0125-1.0 μg/kg. The results of the LC-MS/MS confirmation test on 30 real samples had a good correlation with that of our established method (R2 > 0.98), indicating the practical reliability of the established method. The above results indicated that an ICA based on the Ti3C2Tx@Pt nanozyme has excellent potential as a food safety detection tool.

Biochar with enhanced performance prepared based on “graphite-structure regulation” conjecture designed to effectively control water pollution

In this work, corn straw was used as raw material, Hummers method and activation were used to adjust the graphite structure in biochar, and preparing straw based biochar (H-BCS) with ultra-high specific surface area (3441.80 m2/g), highly total pore volume (1.9859 cm3/g), and further enhanced physicochemical properties. Compared with untreated straw biochar (BCS), the specific surface area and total pore volume of H-BCS were increased by 47.24 % and 55.85 %, respectively. H-BCS showed good removal ability in subsequent experiments by using chloramphenicol (CP), hexavalent chromium (Cr6+), and crystal violet (CV) as adsorption models. In addition, the adsorption capacities of H-BCS (CP: 1396.30 mg/g, Cr6+: 218.40 mg/g, and CV: 1246.24 mg/g) are not only higher than most adsorbents, even after undergoing 5 cycles of regeneration, its adsorption capacity remains above 80 %, indicating significant potential for practical applications. In addition, we also speculated and analyzed the conjecture about the “graphite-structure regulation” during the preparation process, and finally discussed the possible mechanism during the adsorption processes. We hope this work could provide a new strategy to solve the restriction of biochar performance by further exploring the regulation of graphite structure in carbon materials.

A Physical Insight of Phase-Dependent Electron Transfer Kinetic Behaviors and Electrocatalytic Activity of an Iron Oxide-Based Sensing Nanoplatform Towards Chloramphenicol

Insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures is important in the rational design of functional nanostructures for realizing high-performance electrochemical sensors. This study focuses on elucidating the effect of the crystalline phase on the electron transfer kinetics and electrocatalytic activity of iron(III) oxide. The α-FeOOH, γ-Fe2O3, and α-Fe2O3 nanorods were designed by using a simple chemical method and calcining process. The phase-dependent difference in the electron transfer kinetics and electrocatalytic activity toward the sensitive response of chloramphenicol (CAP) is observed by the transformation from α-FeOOH to γ-Fe2O3, and from α-FeOOH to α-Fe2O3 nanorods. We found that the oxygen vacancies formed in phase transformation from α-FeOOH to α-Fe2O3 is a key factor in promoting the electrochemical reduction of chloramphenicol. The α-Fe2O3 nanorods-based electrochemical sensors showed a linear response in the CAP concentration range from 0.1 to 75 μM with a limit of detection of 60 nM and an electrochemical sensitivity of 2.86 μA μM−1 cm−2. This work further provides valuable physical insight into the phase-dependent electron transfer kinetics and electrocatalytic activity of metal oxide nanostructures for the rational design of sensing interface.

Core-shell magnetic molecularly imprinted polymers prepared by self-polymerization of bifunctional monomers for efficient enrichment and separation of chloramphenicol in water samples

Chloramphenicol (CAP) is a potent antibiotic used to treat infections in livestock and humans, but its residues can be hazardous to human health. In this study, amino-modified Fe3O4 nanoparticles were prepared by a single-pot method, and magnetic molecularly imprinted materials were prepared by self-polymerization for imprinting with CAP. The imprinted thin layer was prepared by polymerization of dopamine (DA) and 3-aminophenylboronic acid (APBA) copolymers, which improved the elution efficiency of the template. Dopamine generated under alkaline conditions replaces the crosslinker and can be adsorbed on the surface of magnetic carriers. The aromatic groups in dopamine make it difficult to degrade and fall off after adsorption on the magnetic carrier surface. The maximum adsorption amount of CAP on magnetic materials was 6.5 mg/g. After several adsorption cycles, the CAP-MMIPs still had good stability. The results showed that the method can both specifically recognize and enrich the separation of the target antibiotics, which greatly reduced the pretreatment time of the samples and provided a new approach for the pretreatment of CAP.

A sensitive enzyme-free electrochemical sensor based on ZnWO4/γ-Fe2O3 magnetic molecularly imprinted polymer for specific recognition and determination of Chloramphenicol

A chloramphenicol (CAP) electrochemical sensor based on zinc tungstate and magnetic hematite (ZnWO4/γ-Fe2O3) magnetic molecularly imprinted polymer (ZnWO4/γ-Fe2O3/MIP) is proposed. First, ZnWO4, γ-Fe2O3 nanomaterials were synthesized by one-step hydrothermal method, and then ZnWO4, magnetic nanoparticles were combined with molecularly imprinted polymers, that is, ZnWO4/γ-Fe2O3 was coated with a molecularly imprinted (MIP) shells by precipitation polymerization method to prepare magnetic molecularly imprinted nanomaterials, and then modified on glassy carbon electrodes to construct an electrochemical sensor for the determining of CAP. The results show that under the optimal conditions, the ZnWO4/γ-Fe2O3/MIP (MMIP) modified electrode has a stronger CAP detection reduction peak current than the one-component electrode, and exhibits better electrocatalytic activity, which is an excellent electrochemically modified electrode. Compared to magnetic non-molecular imprint sensors (MNIP), MMIP sensors have higher detection efficiency. The linear range of ZnWO4/γ-Fe2O3/MIP/GCE for the detection of CAP was 0.12 ∼ 1224 μM, and the detection limit was 0.034 μM, showing excellent stability and reproducibility, and good selectivity in the presence of different interferences. ZnWO4/γ-Fe2O3/MIP/GCE was applied to the detection of CAP in milk samples with satisfactory results.

A highly sensitive electrochemical sensor for the detection of chloramphenicol based on Ni/Co bimetallic metal-organic frameworks/reduced graphene oxide composites

A highly and simply sensitive electrochemical sensor has been developed for the detection of trace chloramphenicol (CAP) in water based on Ni/Co bimetallic metal–organic frameworks-reduced graphene oxide composites [rGO/NiCo-BTC MOFs (BTC = 1,3,5-benzenetricarboxylicacid)] modified glassy carbon electrode (GCE/rGO/NiCo-BTC MOFs). The bare glassy carbon electrode was initially coated with graphene oxide (GO). Subsequently, the GO was electrochemically reduced to obtain reduced graphene oxide (rGO). NiCo-BTC MOFs was grown on the surface of rGO modified electrode by in-situ electrochemical synthesis method to construct GCE/rGO/NiCo-BTC MOFs. The as-made composites films have been characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Further, different electrochemical techniques were utilized for investigating the electrochemical reduction behaviors of CAP at GCE/rGO/NiCo-BTC MOFs. This composites film modified electrode combines the large surface area and excellent electrical properties of rGO with the good catalytic activity of NiCo-BTC MOFs, resulting in a significant enhancement of the electrochemical signal during the electroreduction of CAP. Under the optimized experimental conditions, the sensor exhibits excellent sensing performance for CAP, with a wider linear dynamic range (0.1 − 100 μM), a lower limit of detection (0.235 μM) (S/N = 3) and a ultra-high sensitivity (33.12 μA·μM−1·cm−2). The tap water spiked with different concentrations of CAP were considered. The recoveries range from 97.79 % to 100.07 %, with relative standard deviations ranging from 3.45 % to 5.40 %. The method has been successfully applied for the determination of CAP in real samples, yielding satisfactory results. With further research and development, electrochemical in-situ synthesis of MOFs composites have the potential to revolutionize the design and performance of electrochemical sensors, holding great promise in the field of electrochemical sensing.

Validation of electrochemical device setup for detection of dual antibiotic drug release from hydrogel

Due to antimicrobial resistance that occurs throughout the world, antibiotic-releasing hydrogel with at least two drugs that synergistically treat stubborn bacteria is preferable for infection prevention. Hydrogel can serve as a drug reservoir to gradually release drugs in a therapeutic window to effectively treat microorganisms with minimal side effects. The study and development of drug releasing hydrogels requires a reliable, straightforward, cost-effective, fast, and low labor-intensive drug detection technique. In this study, we validate the electrochemical technique and device setup for real-time determination of dual antibacterial drugs released from a hydrogel. Concentrations of two representative antibacterial drugs, tetracycline (TC) and chloramphenicol (CAP), were determined using square wave voltammetry (SWV) mode that yields the lower limit of detection at 2.5 µM for both drugs. Measurement accuracy and repeatability were verified by 36 known drug combination concentrations. Capability in long-term measurement was confirmed by the measurement stability which was found to last for at least 72 h. Stirring was revealed as one of the significant factors for accurate real-time detection. Real-time measurement was ultimately performed to demonstrate the determination of multiple drug releases from a drug releasing hydrogel and validated by high-performance liquid chromatography (HPLC). All the results support that the electrochemical technique with the proposed device design and setup can be used to accurately and simultaneously determine dual drugs that are released from a hydrogel in real-time.

Improving the detection accuracy of the dual SERS aptasensor system with uncontrollable SERS “hot spot” using machine learning tools

BackgroundSimultaneous detection of food contaminants is crucial in addressing the collective health hazards arising from the presence of multiple contaminants. However, traditional multi-competitive surface-enhanced Raman scattering (SERS) aptasensors face difficulties in achieving simultaneous accurate detection of multiple target substances due to the uncontrollable SERS “hot spots”. In this study, using chloramphenicol (CAP) and estradiol (E2) as two target substances, we introduced a novel approach that combines machine learning methods with a dual SERS aptasensor, enabling simultaneous high-sensitivity and accurate detection of both target substances. ResultsThe strategy effectively minimizes the interference from characteristic Raman peaks commonly encountered in traditional multi-competitive SERS aptasensors. For this sensing system, the Au@4-MBA@Ag nanoparticles modified with sulfhydryl (SH)-CAP aptamer and Au@DTNB@Ag NPs modified with sulfhydryl (SH)-E2 aptamer were used as signal probes. Additionally, Fe3O4@Au nanoflowers integrated with SH-CAP aptamer complementary DNA and SH-E2 aptamer complementary DNA were used as capture probes, respectively. When compared to linear regression random forest, and support vector regression (SVR) models, the proposed artificial neural network (ANN) model exhibited superior precision, demonstrating R2 values of 0.963, 0.976, 0.991, and 0.970 for the training set, test set, validation set, and entire dataset, respectively. Validation with ten spectral groups reported an average error of 244 μg L−1. SignificanceThe essence of our study lies in its capacity to address a persistent challenge encountered by traditional multiple competitive SERS aptasensors – the interference generated by uncontrollable SERS “hot spots” that hinders simultaneous quantification. The accuracy of the predictive model for simultaneous detection of two target substances was significantly improved using machine learning tools. This innovative technique offers promising avenues for the accurate and high-sensitive simultaneous detection of multiple food and environmental contaminants.

Antimicrobial liposomes-in-nanofiber wound dressings prepared by a green and sustainable wire-electrospinning set-up

Increasing prevalence of infected and chronic wounds demands improved therapy options. In this work an electrospun nanofiber dressing with liposomes is suggested, focusing on the dressing’s ability to support tissue regeneration and infection control. Chloramphenicol (CAM) was the chosen antibiotic, added to the nanofibers after first embedded in liposomes to maintain a sustained drug release. Nanofibers spun from five different polymer blends were tested, where pectin and polyethylene oxide (PEO) was identified as the most promising polymer blend, showing superior fiber formation and tensile strength. The wire-electrospinning setup (WES) was selected for its pilot-scale features, and water was applied as the only solvent for green electrospinning and to allow direct liposome incorporation. CAM-liposomes were added to Pectin-PEO nanofibers in the next step. Confocal imaging of rhodamine-labelled liposomes indicated intact liposomes in the fibers after electrospinning. This was supported by the observed in vitroCAM-release, showing that Pectin-PEO-nanofibers with CAM-liposomes had a delayed drug release compared to controls. Biological testing confirmed the antimicrobial efficacy of CAM and good biocompatibility of all CAM-nanofibers. The successful fiber formation and green production process with WES gives a promising outlook for industrial upscaling.

Spatially confined CuFe2O4 nanosphere in N/O-codoped porous carbon mimetics for triple-mode sensing of antibiotics and visual detection of neurotransmitters in biofluids

BackgroundCarbon-based nanozymes have recently received enormous concern, however, there is still a huge challenge for inexpensive and large-scale synthesis of magnetic carbon-based “Two-in-One” mimics with both peroxidase (POD)-like and laccase-like activities, especially their potential applications in multi-mode sensing of antibiotics and neurotransmitters in biofluids. Although some progresses have been made in this field, the feasibility of biomass-derived carbon materials with both POD-like and laccase-like activities by polyatomic doping strategy is still unclear. In addition, multi-mode sensing platform can provide a more reliable result because of the self-validation, self-correction and mutual agreement. Nevertheless, the use of magnetic carbon-based nanozyme sensors for the multi-mode detection of antibiotics and neurotransmitters have not been investigated. ResultsWe herein report a shrimp shell-derived N, O-codoped porous carbon confined magnetic CuFe2O4 nanosphere with outstanding laccase-like and POD-like activities for triple-mode sensing of antibiotic d-penicillamine (D-PA) and chloramphenicol (CPL), as well as colorimetric detection of neurotransmitters in biofluids. The magnetic CuFe2O4/N, O-codoped porous carbon (MCNPC) armored mimetics was successfully fabricated using a combined in-situ coordination and high-temperature crystallization method. The synthesized MCNPC composite with superior POD-like activity can be used for colorimetric/temperature/smartphone-based triple-mode detection of D-PA and CPL in goat serum. Importantly, the MCNPC nanozyme can also be used for colorimetric analysis of dopamine and epinephrine in human urine. SignificanceThis work not only offered a novel strategy to large-scale, cheap synthesize magnetic carbon-based “Two-in-One” armored mimetics, but also established the highly sensitive and selective platforms for triple-mode monitoring D-PA and CPL, as well as colorimetric analysis of neurotransmitters in biofluids without any tanglesome sample pretreatment.

Design, optimization and pharmaceutical characterization of wound healing film dressings with chloramphenicol and ibuprofen

Objective The aim of the present study was to develop and optimize a wound dressing film loaded with chloramphenicol (CAM) and ibuprofen (IBU) using a Quality by Design (QbD) approach. Significance The two drugs have been combined in the same dressing as they address two critical aspects of the wound healing process, namely prevention of bacterial infection and reduction of inflammation and pain related to injury. Methods Three critical formulation variables were identified, namely the ratios of Kollicoat SR 30D, polyethylene glycol 400 and polyvinyl alcohol. These variables were further considered as factors of an experimental design, and 17 formulations loaded with CAM and IBU were prepared via solvent casting. The films were characterized in terms of dimensions, mechanical properties and bioadhesion. Additionally, the optimal formulation was characterized regarding tensile properties, swelling behavior, water vapor transmission rate, surface morphology, thermal behavior, goniometry, in vitro drug release, cell viability, and antibacterial activity. Results The film was optimized by setting minimal values for the folding endurance, adhesive force and hardness. The optimally formulated film showed good fluid handling properties in terms of swelling behavior and water vapor transmission rate. IBU and CAM were released from the film up to 80.9% and 82.5% for 8 h. The film was nontoxic, and the antibacterial activity was prominent against Micrococcus spp. and Streptococcus pyogenes. Conclusions The QbD approach was successfully implemented to develop and optimize a novel film dressing promising for the treatment of low-exuding acute wounds prone to infection and inflammation.

Occurrence and Risk Assessment of Antibiotics in Urban River–Wetland–Lake Systems in Southwest China

Antibiotics in the aquatic environment are of great concern as novel contaminants. In this study, we investigated the occurrence, distribution, potential sources, and risk assessment of antibiotics in an interconnected river–wetland–lake system. Thirty-three target antibiotics, including sulfonamides (SAs), macrolides (MLs), fluoroquinolones (FQs), tetracyclines (TCs), and chloramphenicol (CLs) belong to five common groups of antibiotics, were tested from water samples collected in the Panlong River, Xinghai Wetland, and Lake Dian (or Dianchi). Mass spectrophotometry was used to detect the target antibiotics, and the water quality parameters were measured in situ. We found four antibiotics, lincomycin (LIN), trimethoprim (TMP), sulfamethoxazole (SMX), and ofloxacin (OFL), with relatively low concentrations at the ng/L level, and detection rates among sample sites ranged from 42.3% to 76.9%, with maximum concentrations of 0.71 ng/L~5.53 ng/L. TMP was not detected in the Panlong River but appeared in the wetlands and Lake Dian. Midstream urban areas of the Panlong River showed the highest pollution among sites. Antibiotic concentrations were positively correlated with total nitrogen (TN) (p < 0.05) and showed some negative correlation with pH, salinity, and DO. According to the risk assessment, antibiotics in water do not pose a threat to human health and aquatic ecosystems, but a potentially harmful combined effect cannot be excluded. Our research offers a geographical summary of the distribution of antibiotics in urban river, wetland, and lake ecosystems in the plateau (PWL), which is important for predicting the distribution characteristics of antibiotics in the plateau water environment and establishing a standardized antibiotic monitoring and management system for the government.

Ultrasensitive detection of chloramphenicol in water using functionalized polymers with an aluminium organic framework

Metal-Organic Frameworks (MOFs) are extensively used as electrode material in various sensing applications due to their efficacious porous nature and tunable properties. However, pristine MOFs lack conductive attributes that hinder their wide usage in electrochemical applications. Electropolymerization of several aromatic monomers has been a widely used strategy for preparing conducting electrode materials for various sensing applications in the past decades. Herein, we report a similar approach by employing the electropolymerization method to create a functional polymer layer to enhance the sensitivity of an Aluminium Organic Framework (DUT-4) for the selective detection of Chloramphenicol (CAP) antibiotic in aqueous environment. The combined strategy using the conducting polymer layer with the porous Al MOF provides surpassing electrochemical performance for sensing CAP with regard to the very low detection limit (LOD = 39 nM) and exceptionally high sensitivity (11943 μA mM−1 cm−2). In addition, the fabricated sensor exhibited good selectivity, reproducibility and stability. The developed method was successfully evaluated in various real samples including lake water and river water for CAP detection with good recovery percentages even at lower concentrations.

Graphdiyne chelated iron-based metal–organic frameworks for electrochemical sensing of antibiotic chloramphenicol with ultralow detection limit

Chloramphenicol (CAP), a broad-spectrum antibiotic agent that can inhibit protein synthesis, has caused environmental and human health problems upon excessive usage but to realize its ultrasensitive detection is still a great challenge. We report here the design and fabrication of a nanocomposite comprising graphdiyne (GDY) chelated iron-based metal–organic framework (Fe-MOF@GDY) with strong interfacial interaction to achieve high performance electrochemical sensing of CAP. Fe-MOF@GDY exhibits good selectivity, a linear range of 1 pM−24 mM and an ultralow detection limit down to 0.54 pM, among the best performance for CAP detection. It displays good reproducibility and storage stability with retained 98.4% of its initial response after 3 weeks. GDY with unique electronic structure enhances charge transfer of Fe-MOF for improved conductivity, and Fe-MOF nanoparticles are uniformly chelated on GDY for rich active sites towards CAP reduction. Fe-MOF also prevents GDY from being degraded, promoting long-term stability. A portable electrochemical chip is fabricated based on Fe-MOF@GDY, and is successfully used for accurate detection of CAP in lake water with recovery rates of 97.2–104.7%, demonstrating the practical on-site applications.

Quantum biochemical analysis of the TtgR regulator and effectors

The recent expansion of multidrug-resistant (MDR) pathogens poses significant challenges in treating healthcare-associated infections. Although antibacterial resistance occurs by numerous mechanisms, active efflux of the drugs is a critical concern. A single species of efflux pump can produce a simultaneous resistance to several drugs. One of the best-studied efflux pumps is the TtgABC: a tripartite resistance-nodulation-division (RND) efflux pump implicated in the intrinsic antibiotic resistance in Pseudomonas putida DOT-T1E. The expression of the TtgABC gene is down-regulated by the HTH-type transcriptional repressor TtgR. In this context, by employing quantum chemistry methods based on the Density Functional Theory (DFT) within the Molecular Fragmentation with Conjugate Caps (MFCC) approach, we investigate the coupling profiles of the transcriptional regulator TtgR in complex with quercetin (QUE), a natural polyphenolic flavonoid, tetracycline (TAC), and chloramphenicol (CLM), two broad-spectrum antimicrobial agents. Our quantum biochemical computational results show the: [i] convergence radius, [ii] total binding energy, [iii] relevance (energetically) of the ligands regions, and [iv] most relevant amino acids residues of the TtgR-QUE/TAC/CLM complexes, pointing out distinctions and similarities among them. These findings improve the understanding of the binding mechanism of effectors and facilitate the development of new chemicals targeting TtgR, helping in the battle against the rise of resistance to antimicrobial drugs. These advances are crucial in the ongoing fight against rising antimicrobial drug resistance, providing hope for a future where healthcare-associated infections can be more beneficially treated.

Fluorescent immunoassay for chloramphenicol based on the label-free polyadenine-mediated spherical nucleic acids triggered signal amplification.

A fluorescent immunosorbent assay incorporating signal amplification away from the surface of spherical nucleic acid (SNA) was developed for the detection of chloramphenicol (CAP). Through the conjugation of antibodies and poly-adenine (polyA) DNA onto the surface of gold nanoparticles (AuNPs), the fabrication of the nano-immunoprobe was achieved in a more straightforward and cost-effective manner. Moreover, a strategy utilizing the hybridization chain reaction (HCR) in the amplification step was devised, with particular attention given to the enzyme inhibition associated with SNA. The results demonstrated good performance on CAP detection with a linear range of 0.01-5ng/L with a detection limit of 0.005ng/L. The significance of this work mainly lies in the polyA-SNA-based immunoprobe and the thoughtful design to prevent enzyme inhibition.

Chloramphenicol-imprinted polychitosan bounded with carbon dots as fluorescent sensor, dispersive sorbent, and drug carrier.

Chitosan, an abundant natural polysaccharide, was conjugated with carbon dots (CDs) and self-polymerized with chloramphenicol (CAP) templates to synthesize CD-incorporated and molecularly CAP-imprinted polychitosan (CD-MIC). The CD-MIC was used for fluorescent sensing, dispersive sorption, and dosage release of CAP at different pH levels. The sphere of action mechanism, approved by emission and excitation fluorescence, UV-Vis absorption, and fluorescence lifetime measurements, regulated the fluorescence static quenching. By the Perrin model, the quenching extent was linearly correlated to CAP within 0.17 - 33.2μM (LOD = 37nM) at pH 7.0. With an imprinting factor of 3.1, the CD-MIC was more selective for CAP than CD, although it was less sensitive to CAP. The recoveries of 5.0μM CAP from milk matrix were 95% (RSD = 2.3%) for CD-MIC probes and 62% (RSD = 4.5%) for CD. The Langmuir and pseudo-second-order models preferably described the isothermal and kinetic sorptions of CAP into the imprinted cavities in CD-MICs, respectively. The Weber - Morris kinetic model showed three stages involved in intraparticle diffusion, which was pH-dependent and gradually arduous at the later stage, and showed external diffusion partly engaged in the diffusion mechanism. The 20 - 70% of CAP formulated in CAP-embedded CD-MICs were released in 8 - 48h. The release percentage was lower at pH 7.0 than at pH 5.0 and 9.0, but the equilibrium time was shorter. At pH 7.0, the release percentage reached 45% at 10min and slowly increased to 51% at 24h.