Occurrence, toxicity and adsorptive removal of the chloramphenicol antibiotic in water: a review

Beetle-inspired AuNPs semi-embedded colloidal crystal chips for the highly sensitive and colored detection of chloramphenicol in foods

Inspired by the desert beetle, a novel biomimetic chip was developed to detect chloramphenicol (CP). The chip was characterized by a periodic array in which hydrophobic Au nanoparticles (AuNPs) were semi-embedded on hydrophilic polymethyl methacrylate (PMMA) spheres. Among them, the AuNPs exhibited both a localized surface plasmon resonance effect to amplify the reflected signal and a synergistic effect with PMMA spheres to create a significant hydrophilic-hydrophobic interface, which facilitated the enrichment of target CP molecules and improved sensitivity. After optimization, the chip showed direct, ultrasensitive (as low as 0.2 ng/mL), fast (5 min), and selective detection of CP with a wide concentration range extending from 0.2 ng/mL to 1000 ng/mL. During detection, color changes of the chip were observed by naked eyes without any color display equipment. The recovery of CP was between 94.65 % and 108.70 % in chicken and milk samples.

Antenna effect enhanced ECL immunoassay using microfloral europium porphyrin coordination polymers based on Eu3+ and TCPP for the detection of chloramphenicol in foods

The "antenna effect" is one of the most important energy transfer modes in lanthanide light-emitting polymers. In this study, novel luminescent nanostructured coordination polymers (Eu-PCP) were synthesized in one step using Eu3+ as the central metal ion and 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP) as the organic ligand. The unique "antenna effect" observed between Eu3+ and TCPP leads to a substantial improvement in the electrochemiluminescence (ECL) emission efficiency. Eu-PCP exhibits good cathodic ECL characteristics. Additionally, Au@SnS2 nanosheets exhibit favorable electrical conductivity, biocompatibility, and a significant specific surface area. This makes them a suitable choice as substrate materials for the modification of electrode surfaces and capturing antigens. Being well known, the development of sensitive and rapid methods to detect chloramphenicol is essential for food safety. Based on this, we report a novel competitive electrochemiluminescence immunoassay to achieve ultra-sensitive and highly specific detection of chloramphenicol. The linear range was 0.0002-500 ng mL-1 and the detection limit was 0.09 pg mL-1. Apart from that, the experimental results proved that it provided a new analytical tool for the detection of antibiotic residues in food safety.

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 0.01-5 ng/L with a detection limit of 0.005 ng/L. The significance of this work mainly lies in the polyA-SNA-based immunoprobe and the thoughtful design to prevent enzyme inhibition.

Highly enhanced chloramphenicol adsorption performance of MIL-53-NH2(Al)-derived porous carbons modified with tannic acid

The worldwide demand for antibiotics has experienced a notable surge, propelled by the repercussions of the COVID-19 pandemic and advancements in the global healthcare sector. A prominent challenge confronting humanity is the unregulated release of antibiotic-laden wastewater into the environment, posing significant threats to public health. The adoption of affordable carbon-based adsorbents emerges as a promising strategy for mitigating the contamination of antibiotic wastewater. Here, we report the synthesis of novel porous carbons (MPC) through a direct pyrolysis of MIL-53-NH2(Al) and tannic acid (TANA) under N2 atmosphere at 800 °C for 4 h. The effect of TANA amount ratios (0%-20%, wt wt-1) on porous carbon structure and adsorption performance was investigated. Results showed that TANA modification resulted in decreased surface area (1,600 m2 g-1-949 m2 g-1) and pore volume (2.3 cm3 g-1-1.7 cm3 g-1), but supplied hydroxyl functional groups. Adsorption kinetic, intraparticle diffusion, and isotherm were examined, indicating the best fit of Elovich and Langmuir models. 10%-TANA-MPC obtained an ultrahigh adsorption capacity of 564.4 mg g-1, which was approximately 2.1 times higher than that of unmodified porous carbon. 10%-TANA-MPC could be easily recycled up to 5 times, and after reuse, this adsorbent still remained highly stable in morphology and surface area. The contribution of H bonding, pore-filling, electrostatic and π-π interactions to chloramphenicol adsorption was clarified. It is recommended that TANA-modified MIL-53-NH2(Al)-derived porous carbons act as a potential adsorbent for removal of pollutants effectively.

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.

Carbon-dots encapsulated luminescent metal-organic frameworks@surface molecularly imprinted polymer: A facile fluorescent probe for the determination of chloramphenicol

In this study, carbon dots (CDs)-encapsulated luminescent metal-organic frameworks@surface molecularly imprinted polymer (CDs@MOF@SMIP) was facilely prepared and applied as fluorescent probe for specific identification and sensitive detection of chloramphenicol (CAP) in food. Fluorescent CDs, serving as signal tags, were encapsulated within metal-organic backbones (ZIF-8), yielding luminescent MOF materials (CDs@ZIF-8). The synthesized CDs, CDs@ZIF-8 and CDs@ZIF-8@SMIP were investigated by morphological and structural characterizations (UV-Vis, XRD, FT-IR, BET, TEM). The CDs@ZIF-8@SMIP probe was demonstrated to have remarkable selectivity and sensitivity towards CAP. Its fluorescence decreased linearly with CAP concentration from 0.323 μg L-1 (0.001 μM) to 8075.0 μg L-1 (25.0 μM), featuring a low detection limit of 0.08 μg L-1. The CDs@ZIF-8@SMIP-based fluorescence strategy achieved satisfactory recoveries (95.5 % - 101.0 %) in CAP-spiked commercial foods with RSD < 4.4 % (n = 3). These results indicate that this method can effectively detect trace CAP in food matrices and has broad application prospects.

Multilayered Fe3O4@(ZIF-8)3 combined with a computer-vision-enhanced immunosensor for chloramphenicol enrichment and detection

The misuse and overuse of chloramphenicol poses severe threats to food safety and human health. In this work, we developed a magnetic solid-phase extraction (MSPE) pretreatment material coated with a multilayered metal-organic framework (MOF), Fe3O4 @ (ZIF-8)3, for the separation and enrichment of chloramphenicol from fish. Furthermore, we designed an artificial-intelligence-enhanced single microsphere immunosensor. The inherent ultra-high porosity of the MOF and the multilayer assembly strategy allowed for efficient chloramphenicol enrichment (4.51 mg/g within 20 min). Notably, Fe3O4 @ (ZIF-8)3 exhibits a 39.20% increase in adsorption capacity compared to Fe3O4 @ZIF-8. Leveraging the remarkable decoding abilities of artificial intelligence, we achieved the highly sensitive detection of chloramphenicol using a straightforward procedure without the need for specialized equipment, obtaining a notably low detection limit of 46.42 pM. Furthermore, the assay was successfully employed to detect chloramphenicol in fish samples with high accuracy. The developed immunosensor offers a robust point-of-care testing tool for safeguarding food safety and public health.

Catalytic hairpin self-assembly amplification fluorescence detection of chloramphenicol based on cross-shaped DNA and UiO-66

A catalytic hairpin self-assembly (CHA) amplification method was developed for CAP detection based on cross-shaped DNA and UiO-66. MOF was used to quench the fluorescent signal of FAM labeled DNA. Cross-shaped DNA with four fluorophore group (FAM) was utilized to enhance the fluorescent intensity. CAP could open hairpin structure of H-apt and induce CHA reaction. The product of CHA hybridized with cross-shaped DNA, resulting its leaving from the surface of UiO-66 and recovery of fluorescent signal. The limit of detection (LOD) was low to 0.87 pM. This method had been successfully applied for the detection of CAP in actual samples. Importantly, the high sensitivity was attributed to the great amplification efficiency of CHA, strong fluorescent intensity of cross-shaped DNA structure and great fluorescent quenched efficiency of UiO-66.

Effect of pyrolysis temperature on characteristics and chloramphenicol adsorption performance of NH2-MIL-53(Al)-derived amine-functionalized porous carbons

Several activities such as aquaculture, human and feedstock therapies can directly release antibiotics into water. Due to high stability, low hydrolysis and non-biodegradation, they can accumulate in the aqueous environment and transport to aquatic species. Here, we synthesized amine-functionalized porous carbons (ANC) by a direct-pyrolysis process of NH2-MIL-53(Al) as a sacrificial template at between 600 and 900 °C and utilized them to eliminate chloramphenicol antibiotic from water. The NH2-MIL-53(Al)-derived porous carbons obtained high surface areas (304.7-1600 m2 g-1) and chloramphenicol adsorption capacities (148.3-261.5 mg g-1). Several factors such as hydrogen bonding, Yoshida hydrogen bonding, and π-π interaction, hydrophobic interaction possibly controlled adsorption mechanisms. The ANC800 could be reused four cycles along with high stability in structure. As a result, NH2-MIL-53(Al)-derived porous carbons are recommended as recyclable and efficient adsorbents to the treatment of antibiotics in water.

A double defects-dominated flexible TiO2 matrix for in-situ SERS sensing of antibiotic residues in aquatic ecosystem (fish & fishpond water) and their on-site degradation in flowing water

High-performance flexible semiconductor material can be used as an excellent multifunctional matrix for in-situ ultrasensitive surface-enhanced Raman scattering (SERS) detection and synchronous photocatalytic degradation of antibiotic residues in aquatic ecosystem. Here, a calcium-doped TiO2 flexible matrix with double defects (surface oxygen vacancy defect and Ti3+ energy level defect) was developed by its "in-situ one-step" hydrothermal synthesis on cotton fabric for the above purposes. Due to the joint contribution of double defects, a multi-channel charge transfer mode and a high-efficiency carrier separation are achieved, which endows flexible cotton fabric/Ca-doped TiO2 (Cot/Ca-TiO2) substrate with the greatly boosted SERS effect for in-situ detection of antibiotic residues on fish body surface and in fishpond water by a simple wiping or dipping sampling method, even for simultaneous identification of multi-component residues. The detection limits of three antibiotic residues (enrofloxacin, ciprofloxacin and enoxacin) are as low as 10-9 M, which are far lower than the EU standard. More meaningfully, the flexible Cot/Ca-TiO2 can be used as a multifunctional filter-membrane type photocatalyst for efficient on-site degradation of antibiotic residues in flowing fishpond water by a multi-grade photocatalysis means. Moreover, the flexible matrix exhibits good recyclability in both actual detection and photocatalysis.

Porous Fe-Porphyrin as an Efficient Adsorbent for the Removal of Ciprofloxacin from Water

Antibiotics are widely used in medicine, but they are not fully metabolized in the body and can end up in wastewater. Conventional wastewater treatment methods fail to completely remove antibiotic residues, which can then enter rivers and streams. Adsorption is a promising technique for removing antibiotics from wastewater, even at low concentrations. The successful one-pot synthesis of an adsorbent, iron-containing porphyrin-based porous organic polymer (Fe-POP), was achieved through the reaction of pyrrole groups and terephthalaldehyde in the presence of FeCl3. Characterized by a substantial BET surface area of 597 m2 g-1, Fe-POP was systematically investigated for its adsorption potential in the removal of the antibiotic Ciprofloxacin (CIP) from aqueous solutions. By systematic variation of key parameters, including pH, adsorbent loading, and CIP concentration, the adsorption conditions were optimized. Under the optimal conditions at pH = 3, CIP concentration of 5 ppm, and 25 mg of Fe-POP, the maximum adsorption capacity reached an impressive 263 mg g-1. The robust adsorption behavior was elucidated through the fitting of experimental data to the Langmuir adsorption isotherm (R2 = 0.962) and the pseudo-second-order kinetic model (R2 = 0.999) with lower error values. These models suggested that the adsorption process predominantly involved chemical interactions between CIP molecules and the Fe-POP surface. Fe-POP exhibited a robust structure with a high adsorption capacity, showcasing its efficacy in removing CIP contaminants from water. Therefore, Fe-POP can be considered a valuable adsorbent for water treatment applications, specifically for antibiotic removal.

Nanomaterials Based on 2,7,12,17-Tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine Exhibiting Bifunctional Sensitivity for Monitoring Chloramphenicol and Co2

Monitoring antibiotic retention in human body fluids after treatment and controlling heavy metal content in water are important requirements for a healthy society. Therefore, the approach proposed in this study is based on developing new optical sensors using porphyrin or its bifunctional hybrid materials made with AuNPs to accomplish the accurate detection of chloramphenicol and cobalt. To produce the new optical chloramphenicol sensors, 2,7,12,17-tetra-tert-butyl-5,10,15,20-tetraaza-21H,23H-porphine (TBAP) was used, both alone in an acid medium and as a hybrid material with AuNPs in a water-DMSO acidified environment. The same hybrid material in the unchanged water-DMSO medium was the sensing material used for Co2+ monitoring. The best results of the hybrid materials were explained by the synergistic effects between the TBAP azaporphyrin and AuNPs. Chloramphenicol was accurately detected in the range of concentrations between 3.58 × 10-6 M and 3.37 × 10-5 M, and the same hybrid material quantified Co2+ in the concentration range of 8.92 × 10-5 M-1.77 × 10-4 M. In addition, we proved that AuNPs can be used for the detection of azaporphyrin (from 2.66 × 10-5 M to 3.29 × 10-4 M), making them a useful tool to monitor porphyrin retention after cancer imaging procedures or in porphyria disease. In conclusion, we harnessed the multifunctionality of this azaporphyrin and of its newly obtained AuNP plasmonic hybrids to detect chloramphenicol and Co2+ quickly, simply, and with high precision.

Occurrence profiling, risk assessment, and correlations of antimicrobials in surface water and groundwater systems in Southwest Nigeria

The presence of antimicrobials in water has grown into a major global health concern. This study thus focused on the presence, ecological implications, and potential health risks associated with nine antimicrobials: five antibiotics (ampicillin, chloramphenicol, ciprofloxacin, metronidazole, and tetracycline) and four parabens (methylparaben, ethylparaben, propylparaben, and butylparaben) in surface water and groundwater samples collected from three Southwestern States in Nigeria (Osun, Oyo, and Lagos States). These antimicrobials were widely detected across the three States with ciprofloxacin being the most dominant having maximum average concentrations of 189 μg L-1 and 319 μg L-1 in surface water and groundwater respectively. The range of average concentrations of antibiotics in surface water are 47.3-235 μg L-1 (Osun), 27.9-166 μg L-1 (Oyo) and 52.1-159 μg L-1 (Lagos). For groundwater, it is 35.3-180 μg L-1 (Osun), 26.5-181 μg L-1 (Oyo) and 32.3-319 μg L-1 (Lagos). The average concentrations of all parabens were 32.4-153 μg L-1, 53.4-80.1 μg L-1, and 83.2-132 μg L-1 for surface water and 46.7-55.7 μg L-1, 53-117 μg L-1, and 62.4-118 μg L-1 for groundwater in Osun, Oyo, and Lagos States respectively. Methylparaben was most frequently detected paraben with average concentrations of 153 μg L-1 and 117 μg L-1 in surface water and groundwater respectively. The measured environmental concentrations of these antimicrobials pose a significant ecological risk while those of ciprofloxacin and ampicillin pose a high health risk to all population groups studied. The average concentrations of antibiotics investigated in this study exceeded their threshold values for Predicted No-Effect Concentrations (PNEC) associated with resistance selection, except for tetracycline.

Laser flash photolysis and quantum chemical studies of UV degradation of pharmaceutical drug chloramphenicol: Short-lived intermediates, quantum yields and mechanism of photolysis

Using methods of time-resolved and stationary photolysis, HPLC-MS and quantum-chemical calculations by the DFT method, the mechanism of direct UV photolysis of the antibiotic chloramphenicol (CAP) was established. For the first time, short-lived intermediates formed during photolysis were detected. The primary photoprocess is the cleavage of the β-C-C bond relative to the aromatic system with the formation of 4-nitrobenzylalcohol radical and residual aliphatic radical. The first radical in deoxygenated solutions predominantly transforms into para-nitrobenzaldehyde and its secondary photolysis products. In the presence of oxygen, the aromatic radical and para-nitrobenzaldehyde are transformed into para-nitrosobenzoic and para-nitrobenzoic acids as a result of reaction with reactive oxygen species (ROS). Formation of ROS is provoked by reactions of aliphatic radical with dissolved oxygen, so this radical is very important for CAP degradation. The quantum yield of direct photolysis of CAP is ∼3% and does not depend on the presence of dissolved oxygen and on the change of the excitation wavelength in the range of 254-308 nm. Obtained data are important for further understanding of the transformation pathways of CAP and similar PPCP in natural and wastewaters under the action of sunlight and artificial UV radiation.

Mineralization and residue characteristics of chloramphenicol in aerobic soils: evidence from a carbon-14 study

Chloramphenicol, a broad-spectrum antibiotic employed for controlling bacterial infections, presents an intriguing aspect in terms of its environmental fate in soils. 14C-labeled chloramphenicol was used to explore its mineralization and residue characteristics in three distinct agricultural soils in China. The findings revealed a nuanced pattern in the fate of 14C-chloramphenicol, with notable variations among the different soils under investigation. The chloramphenicol extract residue exhibited a reduction of 18.04% in sandy clay soil, 23.04% in clay loam soil, and 21.73% in loamy clay soil. Notably, the mineralization rate in sandy clay soil was 25.22% surpassed that in the other two soils, particularly during the initial stages of incubation. Over time, the diminishing extract residue underwent conversion into minerals and bound residue. The formation rate of bound residue was increased from 44.59 to 53.65% after adding 10% manure, suggesting that chloramphenicol easily binds with soils rich in organic matter. The bound residue is predominantly localized in the humin fraction across all soils. Additionally, the sterilized soil experiments indicated the pivotal role of microorganisms in influencing the fate of chloramphenicol under the specified experimental conditions. In conclusion, this study offers valuable insights into the environmental dynamics of chloramphenicol in soils, emphasizing the importance of soil composition, organic matter content, and microbial activity. The findings contribute to a scientific understanding of the environmental safety implications associated with chloramphenicol usage.

A review on the antibiotic florfenicol: Occurrence, environmental fate, effects, and health risks

Florfenicol, as a replacement for chloramphenicol, can tightly bind to the A site of the 23S rRNA in the 50S subunit of the 70S ribosome, thereby inhibiting protein synthesis and bacterial proliferation. Due to the widespread use in aquaculture and veterinary medicine, florfenicol has been detected in the aquatic environment worldwide. Concerns over the effects and health risks of florfenicol on target and non-target organisms have been raised in recent years. Although the ecotoxicity of florfenicol has been widely reported in different species, no attempt has been made to review the current research progress of florfenicol toxicity, hormesis, and its health risks posed to biota. In this study, a comprehensive literature review was conducted to summarize the effects of florfenicol on various organisms including bacteria, algae, invertebrates, fishes, birds, and mammals. The generation of antibiotic resistant bacteria and spread antibiotic resistant genes, closely associated with hormesis, are pressing environmental health issues stemming from overuse or misuse of antibiotics including florfenicol. Exposure to florfenicol at μg/L-mg/L induced hormetic effects in several algal species, and chromoplasts might serve as a target for florfenicol-induced effects; however, the underlying molecular mechanisms are completely lacking. Exposure to high levels (mg/L) of florfenicol modified the xenobiotic metabolism, antioxidant systems, and energy metabolism, resulting in hepatotoxicity, renal toxicity, immunotoxicity, developmental toxicity, reproductive toxicity, obesogenic effects, and hormesis in different animal species. Mitochondria and the associated energy metabolism are suggested to be the primary targets for florfenicol toxicity in animals, albeit further in-depth investigations are warranted for revealing the long-term effects (e.g., whole-life-cycle impacts, multigenerational effects) of florfenicol, especially at environmental levels, and the underlying mechanisms. This will facilitate the evaluation of potential hormetic effects and construction of adverse outcome pathways for environmental risk assessment and regulation of florfenicol.

Design of MXene-Based Multiporous Nanosheet Stacking Structures Integrating Multiple Synergistic SERS Enhancements for Ultrasensitive Detection of Chloramphenicol

Motivated by the desire for more sensitivity and stable surface-enhanced Raman scattering (SERS) substrates to trace detect chloramphenicol due to its high toxicity and ubiquity, MXene has attracted increasing attention and is encountering the high-priority task of further observably improving detection sensitivity. Herein, a universal SERS optimization strategy that incorporates NH4VO3 to induce few-layer MXenes assembling into multiporous nanosheet stacking structures was innovatively proposed. The synthesized Nb2C-based multiporous nanosheet stacking structure can achieve a low limit of detection of 10-10 M and a high enhancement factor of 2.6 × 109 for MeB molecules, whose detection sensitivity is improved by 3 orders of magnitude relative to few-layer Nb2C MXenes. Such remarkably enhanced SERS sensitivity mainly originates from the multiple synergistic contributions of the developed physical adsorption, the chemical enhancement, and the conspicuously improved electromagnetic enhancement arising from the intersecting MXenes. Furthermore, the improved SERS sensitivity endows Nb2C-based multiporous structures with the capability to achieve ultrasensitive detection of chloramphenicol with a wide linear range from 100 μg/mL to 1 ng/mL. We believe it is of great significance in conspicuously developing the SERS sensitivity of other MXenes with surficial negative charges and has a great promising perspective for the trace detection of other antibiotics in microsystems.

Self-Assembled Aminated and TEMPO Cellulose Nanofibers (Am/TEMPO-CNF) Aerogel for Adsorptive Removal of Oxytetracycline and Chloramphenicol Antibiotics from Water

Antibiotics are used for the well-being of human beings and other animals. Detectable levels of antibiotics can be found in pharmaceutical, municipal, and animal effluents. Therefore, the treatment of antibiotic contaminated water is of great concern. In this study, we fabricated a sustainable aminated/TEMPO cellulose nanofiber (Am/TEMPO-CNF) aerogel to remove oxytetracycline (OTC) and chloramphenicol (CAP) from synthetic wastewater. The prepared aerogel was characterized using different analytical techniques such as elemental analysis, FTIR, TGA, SEM-EDS, and N2 adsorption-desorption isotherms. The characterization techniques confirmed the presence and interaction of quaternary amine -[NR3]+ and -COOH groups on Am/TEMPO-CNF with OTC and CAP, which validates the successful modification of Am/TEMPO-CNF. The adsorption process of the pollutants was examined as a function of solution pH, concentrations, reaction time, and temperatures. The maximum adsorption capacity was 153.13 and 150.15 mg/g for OTC and CAP, respectively. The pseudo-second order (PSO-2) was well fitted to both OTC and CAP, confirming the removal is via chemisorption. Hydrogen bonding and electrostatic attraction have been postulated as key factors in facilitating OTC and CAP adsorption according to spectroscopic studies. Energetically, the adsorption was spontaneous and endothermic for both pollutants. In conclusion, the efficient removal rate and excellent reusability of Am/TEMPO-CNF indicate the strong potential of the adsorbent for antibiotics' removal.

Precursor-oriented design of nano-alumina for efficient removal of antibiotics

Rapid and efficient removal of environmental antibiotics is vital to curb bacterial resistance. Through rational precursors-oriented design, we attain the best Al2O3 absorbent by 500 °C calcination of ammonium aluminium carbonate hydroxide (AACH) precursor from NH4HCO3 route (AACH-NH4HCO3-500) for fast and efficient removal of tetracycline (TC) and other antibiotics from environmental waters including high-salinity wastewater. AACH-NH4HCO3-500 (0.25 g·L-1) can remove (69.92 ± 1.78)% of aqueous TC (0.025 g·L-1) within 5 min and (97.62 ± 2.75)% within 2 h, and the adsorption capacity is 444.4 mg·g-1, which is the highest qmax of TC for the 2 h-adsorptions among numerous adsorbents. AACH-NH4HCO3-500 has fine tolerance to the coexisting substances, and can be easily regenerated and reused, and has no harm even discarded. The relations among the synthetic methods, the structural features, and the adsorption functions of Al2O3 are disclosed through a systematic comparison of the commercial Al2O3 and different Al2O3 nanomaterials attained from three precursors produced by five different routes. The reasons behind the exceptional adsorption performance are discussed throughout. Our findings would facilitate the development of excellent adsorbents for removal of other pollutants.

Characteristics of microplastic-derived dissolved organic matter and its binding with pharmaceuticals unveiled by fluorescence spectroscopy and two-dimensional correlation spectroscopy

Microplastics were an extensively detected pollutant in the environment, but microplastic-derived dissolved organic matter (MP-DOM) has received less attention, much less its impact on the binding behavior of pollutants (e.g., pharmaceuticals). In this study, DOM derived from two typical MPs, i.e., polyethylene terephthalate (PET) and polystyrene (PS) was generated by UV irradiation (a widely used way for MPs' aging treatment) and characterized by multiple spectroscopic techniques and methods. Chloramphenicol (CAP) and carbamazepine (CBZ) were selected to investigate the binding mechanism between MP-DOM and pharmaceuticals. After UV irradiation, the concentration of the dissolved organic carbon, colored DOM, and carboxyl/carbonyl groups of MP-DOM increased. Moreover, the humic-like substance released preceding and more under UV irradiation. Furthermore, the protein-like substances on PET-DOM and the humic-like substances on PS-DOM were positively correlated to the binding capacity to the pharmaceuticals, respectively. 2D-COS results revealed that the fluorescent materials having more oxygen-containing functional groups for MP-DOM preferentially interacted with the pharmaceuticals. Overall, the higher fluorescence quenching was related to the protein-like substance, CBZ, and PET-DOM as compared to the humic-like substance, CAP, and PS-DOM. It was verified by the relatively high binding ability (logKM) for them (the protein-like substance: 5.15; CBZ: 4.61; PET: 4.48). This study first proved the environmental reactivity of MP-DOM to the pharmaceuticals highlighting the significance of the spectral properties for the binding behavior of MP-DOM with pharmaceuticals and the competitive sorption role of MP-DOM to the pollutants in the natural environment.

Simultaneous optimization of production yield and sulfadiazine adsorption of MgFe2O4 loaded on prickly pear biochars using Box-Behnken design

A major challenge that humans facing is the uncontrolled discharge of antibiotic-containing wastewater into the environment, accompanying with huge threats to human community. The utilization of cost-effective biomass-based adsorbents is considered a potential solution for the treatment of antibiotic wastewater. This study aims to optimize the synthesis of MgFe2O4 nanoparticles loaded on prickly pear biochar (PPB) with outstanding sulfadiazine adsorbability using response surface methodology. Thirteen materials (MgFe2O4-PPB) produced based on Box-Behnken design were tested to evaluate the impact of the main factors on the material preparation process, including ratio of MgFe2O4:PPB precursors, calcination temperature and calcination time. Under optimized conditions, i.e., MgFe2O4:PPB ratio 0.5, temperature 600 °C and time 1 h, the production yield of 46.5% and sulfadiazine removal percentage of 85.4% were obtained. Characterization of optimized MgFe2O4-PPB indicated the good porosity and functionality suitable for the adsorption of sulfadiazine. Elovich model showed the best description of kinetic process. Temkin model was considered to be an accurate description of the isotherm adsorption. Proposed mechanism for antibiotic adsorption onto MgFe2O4-PPB was described. We clarify cost-benefit analysis to asses the importance of MgFe2O4-PPB as well as the economic and environmental impacts of biochar-based composites.

On-site detection of chloramphenicol in fish using SERS-based magnetic aptasensor coupled with a handheld Raman spectrometer

In recent years, the rapid detection of chloramphenicol (CAP) has become a market demand due to its high toxicity. In this study, for the first time, a portable surface-enhanced Raman scattering (SERS) aptasensor for the rapid and on-site detection of chloramphenicol (CAP) residues in fish was developed. Fe3O4@Au nanoflowers combined with sulfhydryl (SH)-CAP aptamer complementary DNA acted as capture probes. SH-CAP aptamer modified Au@Ag nanoparticles (Au@Ag NPs) embedded with 4-mercaptobenzoic acid (4-MBA) were served as reporter probes. The strongest Raman intensity was produced due to the coupling of Fe3O4@Au nanoflowers (Fe3O4@Au NFs) and Au@Ag NPs. For CAP detection, a wide linear range from 0.001 to 1000 μg/L, with an R2 of 0.9805, was obtained. The limit of detection was determined to be 0.87 ng/L. The SERS aptasensor showed excellent performance for analytical applications for real fish samples. Compared with the conventional HPLC method, the developed SERS aptasensor coupled with a handheld Raman spectrometer had flexible application and avoided the limitations of complex operating conditions. It should be a promising portable analytical tool for analysis of drug residues in the field.

Potential-Resolved Electrochemiluminescence Multiplex Immunoassay for Florfenicol and Chloramphenicol in a Single Sample

The simultaneous detection of multiple antibiotic residues in food is of great significance for food safety. In this work, a novel dual-potential electrochemiluminescence (ECL) immunoassay was designed for the simultaneous detection of chloramphenicol and fluorfenicol residues in food. Ru@MOF was used as an anodic probe, and SnS2 QDs-PEI-Au-MoS2 was used as a cathodic probe. Notably, the coreactant for both luminophores was K2S2O8, avoiding interactions caused by different kinds of coreactants. Au nanoparticles functionalized with a nitrogen- and sulfur-doped graphene oxide-modified glassy carbon electrode to improve the electron transfer efficiency and provide a larger surface area for immobilization of antigen. The linear range for the detection of florfenicol was determined to be 0.1-1000 ng mL-1 with a detection limit of 0.03 ng mL-1, and the linear range for the detection of chloramphenicol was 0.01-1000 ng mL-1 with a detection limit of 3.2 pg mL-1 by recording the ECL responses at two different excitation potentials. The proposed immunoassay achieved a more stable recovery in the detection of actual samples and provided a new analytical method for the simultaneous detection of florfenicol and chloramphenicol residues with high sensitivity and specificity.

Occurrence, toxicity, impact and removal of selected non-steroidal anti-inflammatory drugs (NSAIDs): A review

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most frequently used pharmaceuticals for human therapy, pet therapeutics, and veterinary feeds, enabling them to enter into water sources such as wastewater, soil and sediment, and seawater. The control of NSAIDs has led to the advent of the novel materials for treatment techniques. Herein, we review the occurrence, impact and toxicity of NSAIDs against aquatic microorganisms, plants and humans. Typical NSAIDs, e.g., ibuprofen, ketoprofen, diclofenac, naproxen and aspirin were detected at high concentrations in wastewater up to 2,747,000 ng L-1. NSAIDs in water could cause genotoxicity, endocrine disruption, locomotive disorders, body deformations, organs damage, and photosynthetic corruption. Considering treatment methods, among adsorbents for removal of NSAIDs from water, metal-organic frameworks (10.7-638 mg g-1) and advanced porous carbons (7.4-400 mg g-1) were the most robust. Therefore, these carbon-based adsorbents showed promise in efficiency for the treatment of NSAIDs.

Occurrence and removal of antibiotics from aquaculture wastewater by solar-driven Fe(VI)/oxone process

In this study, the occurrence and removal of ten selected antibiotics from aquaculture wastewater by the process solar + Fe(VI)+oxone were investigated. The detection levels of the antibiotics in the aquaculture wastewater samples were at ng/L. The degradation of the selected antibiotics under the process solar + Fe(VI)+oxone followed pseudo-first-order kinetics. As the most abundant antibiotic in the studied aquaculture wastewater, norfloxacin (NFX) was used as the model compound to study the reaction mechanism and detoxification ability of the treatment system, as well as the effects of reaction parameters and environmental factors. The active species including O2•-, O21, and Fe(V)/Fe(IV) contributed to NFX degradation in the process solar + Fe(VI)+oxone. Decarboxylation, the piprazine ring opening, defluorination of the benzene ring, oxygen addition and the cleavage of the quinolone/benzene ring were main degradation pathways of NFX. Around 20% mineralization was reached and the inhibition rate of the bacteria (Escherichia Coli) growth was reduced from 95.5% to 47.1% after the NFX degradation for 60 min. Despite the suppression of NFX degradation by NO2-, PO43- and humic acid, the NFX degradation in three aquaculture wastewater samples was faster than that in ultrapure water due to the positive effect of Br-and other factors. The above results demonstrate the treatment process solar-driven Fe(VI)/oxone has a good potential in antibiotics removal from the aquaculture wastewater.

Formation of dichloroacetic acid and dichloroacetamide from phenicol antibiotic abatement during ozonation and post-chlor(am)ination

This study investigated the formation of dichloroacetamide (DCAM) and dichloroacetic acid (DCAA) from the abatement of three phenicol antibiotics (PABs, chloramphenicol, thiamphenicol, and florfenicol) during ozonation and post-chlor(am)ination. Results show that the three PABs have a low ozone reactivity (kO3 = 0.11‒0.12 M-1 s-1), and therefore are mainly abated through the hydrogen abstraction mechanism by hydroxyl radicals (•OH) during ozonation. During PAB degradation, the carboxamide moiety in the parent molecules can be cleaved off by •OH attack and thus gives rise to DCAM. The formed DCAM can then be further oxidized by O3 and/or •OH to DCAA as a more stable transformation product (TP). When the three PABs were adequately abated (abatement efficiency of ∼82 %‒95 %), the molar yields of DCAM and DCAA were determined to be 2.79 %‒4.71 % and 32.9 %‒37.2 %, respectively. Furthermore, post-chloramination of the ozonation effluents increased the yields of DCAM and DCAA slightly to 4.20 %‒6.45 % and 39.0 %‒41.1 %, respectively. In comparison, post-chlorination eliminated DCAM in the solutions, but significantly increased DCAA yields to ∼100 % due to the further conversion of DCAM and other ozonation TPs to DCAA by chlorine oxidation. The results of this study indicate that high yields of DCAM and DCAA can be generated from PAB degradation during ozonation, and post-chlorination and post-chloramination will result in very different fates of DCAM and DCAA in the disinfected effluent. The formation and transformation of DCAM and DCAA during PAB degradation need to be taken into account when selecting multi-barrier treatment processes for the treatment of PAB-containing water.

Simultaneous removal of norfloxacin and chloramphenicol using cold atmospheric plasma jet (CAPJ): Enhanced performance, synergistic effect, plasma-activated water (PAW) contribution, mechanism and toxicity evaluation

The extensive abuse and inadvertent discharge of various antibiotics into the environment has become a serious problem for posing a big threat to human health. In order to deal with this problem, we utilized cold atmospheric plasma jet (CAPJ) to treat two different antibiotics, namely, norfloxacin and chloramphenicol, and investigated the efficiencies and corresponding mechanisms for removing the mixed antibiotics. In the application of the CAPJ technique, we made use of not only the direct plasma processing, but also the indirect plasma-activated water (PAW) treatment. The efficiency for mixed antibiotics treatment was considerably enhanced as compared to the efficiency for treatment of single antibiotics. The contributions from the CAPJ-induced reactive oxygen/nitrogen species (RONS) were examined, showing that ·OH and ¹O₂ played a major role in the degradation of norfloxacin and chloramphenicol in the direct plasma treatment, while ¹O₂ played a major role in the PAW treatment. The bio-toxicity evaluation was also provided to verify the ecological safety of the CAPJ treatment. As such, this work has not only showed the effectiveness of CAPJ treatment of mixed antibiotics, but also elucidated the mechanisms for the enhanced treatment efficiency, which may provide a new solution for treatment of antibiotics in the environment.

Novel ZIF-67-derived Co@CNTs nanocomposites as effective adsorbents for removal of tetracycline and sulfadiazine antibiotics

Tetracycline (TCC) and sulfadiazine (SDZ) are two of the most consumed antibiotics for human therapies and bacterial infection treatments in aquafarming fields, but their accumulative residues can result in negative effects on water and aquatic microorganisms. Removal techniques are therefore required to purify water before use. Herein, we concentrate on adsorptive removal of TCC and SDZ using cobalt@carbon nanotubes (Co@CNTs) derived from Co-ZIF-67. The presence of CNTs on the edge of nanocomposites was observed. Taguchi orthogonal array was designed with four variables including initial concentration (5-20 mg L^-1), dosage (0.05-0.2 g L^-1), time (60-240 min), and pH (2-10). Concentration and pH were found to be main contributors to adsorption of tetracycline and sulfadiazine, respectively. The optimum condition was found at concentration 5 mg L^-1, dosage 0.2 g L^-1, contact time 240 min, and pH 7 for both TCC and SDZ removals. Confirmation tests showed that Co@CNTs-700 removed 99.6% of TCC and 97.3% of SDZ with small errors (3-5.5%). Moreover, the kinetic and isotherm were studied, which kinetic and isotherm data were best fitted with pseudo second-order model and Langmuir. Maximum adsorption capacity values for TCC and SDZ were determined at 118.4-174.1 mg g^-1 for 180 min. We also proposed the main role of interactions such as hydrogen bonding, π-π stacking, and electrostatic attraction in the adsorption of antibiotics. With high adsorption performance, Co@CNTs-700 is expected to remove antibiotics efficiently from wastewater.

Effectively facilitating the degradation of chloramphenicol by the synergism of Shewanella oneidensis MR-1 and the metal-organic framework

Electroactive bacteria (EAB) and metal oxides are capable of synergistically removing chloramphenicol (CAP). However, the effects of redox-active metal-organic frameworks (MOFs) on CAP degradation with EAB are not yet known. This study investigated the synergism of iron-based MOFs (Fe-MIL-101) and Shewanella oneidensis MR-1 on CAP degradation. 0.5 g/L Fe-MIL-101 with more possible active sites led to a three-fold higher CAP removal rate in the synergistic system with MR-1 (initial bacterial concentration of 0.2 at OD₆₀₀), and showed a superior catalytic effect than exogenously added Fe(III)/Fe(II) or magnetite. Mass spectrometry revealed that CAP was transformed into smaller molecular weight and less toxic metabolites in cultures. Transcriptomic analysis showed that Fe-MIL-101 enhanced the expression of genes related to nitro and chlorinated contaminants degradation. Additionally, genes encoding hydrogenases and c-type cytochromes associated with extracellular electron transfer were significantly upregulated, which may contribute to the simultaneous bioreduction of CAP both intracellularly and extracellularly. These results indicated that Fe-MIL-101 can be used as a catalyst to synergize with EAB to effectively facilitate CAP degradation, which might shed new light on the application in the in situ bioremediation of antibiotic-contaminated environments.

ZnO/C nanocomposite grafted molecularly imprinted polymers as photoelectrochemical sensing interface for ultrasensitive and selective detection of chloramphenicol

Nanomaterials-based photoelectrochemical (PEC) detection is becoming a rapidly-developing analytical technique in chemical and biological assays due to its unique advantages of easy miniaturization, high sensitivity, and rapid turnaround time. Herein, a molecularly imprinted polymer-assisted PEC sensor based on ZnO/C nanocomposite was successfully fabricated for the highly sensitive and selective determination of chloramphenicol (CAP). Benefiting from the hydrophilic functional groups (-OH, -COOH) and large surface area of bio-templated ZnO/C nanocomposite, the tight grafting of MIP with excellent recognition ability on substrate is easier and more stable than traditional PEC sensor, thus significantly increasing the performance. Under optimal conditions, the PEC sensor exhibited significant CAP detection performance in the range of 0.01-5000 ng mL^-1 with a detection LOD of 5.08 pg mL^-1 (S/N = 3) and successfully applied to the detection of CAP in milk sample. Our results show that ZnO/C nanocomposite and MIP can act as an efficient photo-responsible matrix to fabricate PEC sensor, providing important application potentials for pollutants control in food and environment.

A critical review on pineapple (Ananas comosus) wastes for water treatment, challenges and future prospects towards circular economy

Each year, nearly 30 million tons of pineapple fruit are harvested for food and drinking industries, along with the release of a huge amount of pineapple wastes. Without the proper treatment, pineapple wastes can cause adverse impacts on the environment, calling for new technologies to convert them into valuable products. Here, we review the production and application of adsorbents derived from pineapple wastes. The thermal processing or chemical modification improved the surface chemistry and porosity of these adsorbents. The specific surface areas of the pineapple wastes-based adsorbents were in range from 4.2 to at 522.9 m²·g^-1. Almost adsorption systems followed the pseudo second order kinetic model, and Langmuir isotherm model. The adsorption mechanism was found with the major role of electrostatic attraction, complexation, chelation, and ion exchange. The pineapple wastes based adsorbents could be easily regenerated. We suggest the potential of the pineapple wastes towards circular economy.

An Effective Electrochemical Platform for Chloramphenicol Detection Based on Carbon-Doped Boron Nitride Nanosheets

Currently, accurate quantification of antibiotics is a prerequisite for health care and environmental governance. The present work demonstrated a novel and effective electrochemical strategy for chloramphenicol (CAP) detection using carbon-doped hexagonal boron nitride (C-BN) as the sensing medium. The C-BN nanosheets were synthesized by a molten-salt method and fully characterized using various techniques. The electrochemical performances of C-BN nanosheets were studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the electrocatalytic activity of h-BN was significantly enhanced by carbon doping. Carbon doping can provide abundant active sites and improve electrical conductivity. Therefore, a C-BN-modified glassy carbon electrode (C-BN/GCE) was employed to determine CAP by differential pulse voltammetry (DPV). The sensor showed convincing analytical performance, such as a wide concentration range (0.1 µM-200 µM, 200 µM-700 µM) and low limit of detection (LOD, 0.035 µM). In addition, the proposed method had high selectivity and desired stability, and can be applied for CAP detection in actual samples. It is believed that defect-engineered h-BN nanomaterials possess a wide range of applications in electrochemical sensors.

A dual purpose aluminum-based metal organic framework for the removal of chloramphenicol from wastewater

The presence of antibiotics in the aquatic environment can cause significant environmental and human health problems even at trace concentrations. Conventional treatment systems alone are ineffective in removing these resistant antibiotics. To address this problem, oxidation and adsorption techniques were used to explore the removal of recalcitrant antibiotic chloramphenicol (CAP). An aluminum-based metal-organic framework (Al-MIL) with high surface area and extended porosity, was prepared and used both as adsorbent and catalyst for the oxidation of CAP. Characterization of the Al-MIL revealed a large surface area of 1137 m² g^-1, a homogeneous microporous structure, good crystallinity, and particle size in the range of 200-400 nm. Adsorption of CAP on Al-MIL achieved equilibrium after 1 h, reaching a maximum adsorption capacity of 96.1 mg g^-1 at the optimum pH value of 5.3. The combination of adsorption and oxidation did not improve the % TOC reduction considerably, indicating an antagonistic rather than synergistic effect between the two processes. Oxidation alone in the presence of persulfate, achieved a % TOC reduction of 71% after 2 h, compared to 56% achieved by adsorption alone at the same duration. The optimum persulfate concentration was determined as 2.5 mM. The Al-MIL structure did not demonstrate any substantial deterioriation after six repeated runs, according to the reusability experiments.

Facile synthesis of CoFe2O4@MIL-53(Al) nanocomposite for fast dye removal: Adsorption models, optimization and recyclability

The global occurrence of textile dyes pollution has recently emerged, posing a serious threat to ecological systems. To abate dye contamination, we here developed a novel magnetic porous CoFe₂O₄@MIL-53(Al) nanocomposite by incorporating magnetic CoFe₂O₄ nanoparticles with MIL-53(Al) metal-organic framework. This nanocomposite possessed a surface area of 197.144 m² g^-1 and a pore volume of 0.413 cm³ g^-1. The effect of contact time (5-120 min), concentration (5-50 mg L^-1), dosage (0.1-1.0 g L^-1), and pH (2-10) on Congo red adsorption was clarified. CoFe₂O₄@MIL-53(Al) could remove 95.85% of Cong red dye from water with an accelerated kinetic rate of 0.6544 min^-1 within 10 min. The kinetic and isotherm models showed the predominance of Bangham and Temkin. According to Langmuir, the maximum uptake capacities of CoFe₂O₄@MIL-53(Al), CoFe₂O₄, and MIL-53(Al) adsorbents were 43.768, 17.982, and 15.295 mg g^-1, respectively. CoFe₂O₄@MIL-53(Al) was selected to optimize Cong red treatment using Box-Behnken experimental design. The outcomes showed that CoFe₂O₄@MIL-53(Al) achieved the highest experimental uptake capacity of 35.919 mg g^-1 at concentration (29.966 mg L^-1), time (14.926 min), and dosage (0.486 g L^-1). CoFe₂O₄@MIL-53(Al) could treat dye mixture (methylene blue, methyl orange, Congo red, malachite green, and crystal violet) with an outstanding removal efficiency of 81.24% for 30 min, and could be reused up to five cycles. Therefore, novel recyclable and stable CoFe₂O₄@MIL-53(Al) is recommended to integrate well with real dye treatments systems.

Removal of chloramphenicol antibiotics in natural and engineered water systems: Review of reaction mechanisms and product toxicity

Chloramphenicol antibiotics are widely applied in human and veterinary medicine. They experience natural attenuation and/or chemical degradation during oxidative water treatment. However, the environmental risks posed by the transformation products of such organic contaminants remain largely unknown from the literature. As such, this review aims to summarize and analyze the elimination efficiency, reaction mechanisms, and resulting product risks of three typical chloramphenicol antibiotics (chloramphenicol, thiamphenicol, and florfenicol) from these transformation processes. The obtained results suggest that limited attenuation of these micropollutants is observed during hydrolysis, biodegradation, and photolysis. Comparatively, prominent abatement of these compounds is accomplished using advanced oxidation processes; however, efficient mineralization is still difficult given the formation of recalcitrant products. The in silico prediction on the multi-endpoint toxicity and biodegradability of different products is systematically performed. Most of the transformation products are estimated with acute and chronic aquatic toxicity, genotoxicity, and developmental toxicity. Furthermore, the overall reaction mechanisms of these contaminants induced by multiple oxidizing species are revealed. Overall, this review unveils the non-overlooked and serious secondary risks and biodegradability recalcitrance of the degradation products of chloramphenicol antibiotics using a combined experimental and theoretical method. Strategic improvements of current treatment technologies are strongly recommended for complete water decontamination.

Recent Advances in Carbon-Based Materials for Adsorptive and Photocatalytic Antibiotic Removal

Antibiotics have been a primary environmental concern due to their widespread dispersion, harmful bioaccumulation, and resistance to mineralization. Unfortunately, typical processes in wastewater treatment plants are insufficient for complete antibiotic removal, and their derivatives in effluent can pose a threat to human health and aquatic communities. Adsorption and photocatalysis are proven to be the most commonly used and promising tertiary treatment methods. Carbon-based materials, especially those based on graphene, carbon nanotube, biochar, and hierarchical porous carbon, have attracted much attention in antibiotic removal as green adsorbents and photocatalysts because of their availability, unique pore structures, and superior physicochemical properties. This review provides an overview of the characteristics of the four most commonly used carbonaceous materials and their applications in antibiotic removal via adsorption and photodegradation, and the preparation of carbonaceous materials and remediation properties regarding target contaminants are clarified. Meanwhile, the fundamental adsorption and photodegradation mechanisms and influencing factors are summarized. Finally, existing problems and future research needs are put forward. This work is expected to inspire subsequent research in carbon-based adsorbent and photocatalyst design, particularly for antibiotics removal.

Green synthesis of Mn3O4 nanoparticles using Costus woodsonii flowers extract for effective removal of malachite green dye

The pollution of organic dyes such as malachite green is one of the globally critical issues, calling for efficient mitigation methods. Herein, we developed green Mn₃O₄ nanoparticles synthesized using natural compounds extracted from Costus woodsonii flowers under an ultrasound-assisted mode. The materials were characterized using several physicochemical techniques such as Fourier-transform infrared spectroscopy, X-ray diffraction, Energy-dispersive X-ray spectroscopy, scanning electron microscopy, Raman spectroscopy, and N₂ adsorption desorption isotherm measurement. The X-ray diffraction and N₂ isotherm plots confirmed the presence of tetragonal γ-Mn₃O₄ phase and mesoporous structure, respectively. Carbonyl groups derived from flavonoids or carboxylic compounds were found in the surface of green Mn₃O₄ nanoparticles. The effect of pH, contact time, dose, and concentration on the adsorption of malachite green over green Mn₃O₄ was carried out. The maximum malachite green adsorption capacity for green Mn₃O₄ nanoparticles was 101-162 mg g^-1. Moreover, kinetic and isotherm adsorption of malachite green obeyed Langmuir (R_adj.² = 0.980-0.995) and pseudo first-order models (R_adj.² = 0.996-1.00), respectively. Adsorption of malachite green over green Mn₃O₄ was a thermodynamically spontaneous process due to negative Gibbs free energy values (ΔG^ο < 0). Green Mn₃O₄ nanoparticles offered a high stability through the FR-IR spectra analysis. With a good recyclability of 4 cycles, green Mn₃O₄ nanoparticles can be used as potential adsorbent for removing malachite green dye from water.

Deciphering chloramphenicol biotransformation mechanisms and microbial interactions via integrated multi-omics and cultivation-dependent approaches

BACKGROUND

As a widely used broad-spectrum antibiotic, chloramphenicol is prone to be released into environments, thus resulting in the disturbance of ecosystem stability as well as the emergence of antibiotic resistance genes. Microbes play a vital role in the decomposition of chloramphenicol in the environment, and the biotransformation processes are especially dependent on synergistic interactions and metabolite exchanges among microbes. Herein, the comprehensive chloramphenicol biotransformation pathway, key metabolic enzymes, and interspecies interactions in an activated sludge-enriched consortium were elucidated using integrated multi-omics and cultivation-based approaches.

RESULTS

The initial biotransformation steps were the oxidization at the C₁-OH and C₃-OH groups, the isomerization at C₂, and the acetylation at C₃-OH of chloramphenicol. Among them, the isomerization is an entirely new biotransformation pathway of chloramphenicol discovered for the first time. Furthermore, we identified a novel glucose-methanol-choline oxidoreductase responsible for the oxidization of the C₃-OH group in Sphingomonas sp. and Caballeronia sp. Moreover, the subsequent biotransformation steps, corresponding catalyzing enzymes, and the microbial players responsible for each step were deciphered. Synergistic interactions between Sphingomonas sp. and Caballeronia sp. or Cupriavidus sp. significantly promoted chloramphenicol mineralization, and the substrate exchange interaction network occurred actively among key microbes.

CONCLUSION

This study provides desirable strain and enzyme resources for enhanced bioremediation of chloramphenicol-contaminated hotspot sites such as pharmaceutical wastewater and livestock and poultry wastewater. The in-depth understanding of the chloramphenicol biotransformation mechanisms and microbial interactions will not only guide the bioremediation of organic pollutants but also provide valuable knowledge for environmental microbiology and biotechnological exploitation. Video Abstract.

Deciphering a novel chloramphenicols resistance mechanism: Oxidative inactivation of the propanediol pharmacophore

Expanding knowledge about new types of antibiotic resistance genes is of great significance in dealing with the global antibiotic resistance crisis. Herein, a novel oxidoreductase capO was discovered to be responsible for oxidative inactivation of chloramphenicol and thiamphenicol. The antibiotic resistance mechanism was comprehensively deciphered using multi-omics and multiscale computational approaches. A 66,383 bp DNA fragment carrying capO was shared among four chloramphenicol-resistant strains, and the co-occurrence of capO with a mobile genetic element cluster revealed its potential mobility among different taxa. Metagenomic analysis of 772 datasets indicated that chloramphenicol was the crucial driving factor for the development and accumulation of capO in activated sludge bioreactors treating antibiotic production wastewater. Therefore, we should pay sufficient attention to its possible prevalence and transfer to pathogens, especially in some hotspot environments contaminated with high concentrations of chloramphenicols. This finding significantly expands our knowledge boundary about chloramphenicols resistance mechanisms.