Current bioanalytical methods for detection of penicillins

Nanoassemblies of acetylcholinesterase and β-lactamase immobilized on magnetic nanoparticles as biosensors to detect pollutants in water

The use of enzymes immobilized on magnetic nanoparticles to detect contaminants in aqueous samples has gained interest, since it allows the magnetic control, concentration and reuse of the enzymes. In this work, the detection of trace amounts of organophosphate pesticides (chlorpyrifos) and antibiotics (penicillin G) in water was attained by developing a nanoassembly formed by either inorganic or biomimetic magnetic nanoparticles used as substrates to immobilize acetylcholinesterase (AChE) and β-lactamase (BL). Other than the substrate, the optimization of the nanoassembly was done by testing enzyme immobilization both through electrostatic interaction (also reinforced with glutaraldehyde) and covalent bonds (by carbodiimide chemistry). Temperature (25 °C), ionic strength (150 mM NaCl) and pH (7) were set to ensure enzymatic stability and to allow both the nanoparticles and the enzymes to present ionic charges that would allow electrostatic interaction. Under these conditions, the enzyme load on the nanoparticles was ⁓0.1 mg enzyme per mg nanoparticles, and the preserved activity after immobilization was 50-60% of the specific activity of the free enzyme, being covalent bonding the one which yielded better results. Covalent nanoassemblies could detect trace concentrations of pollutants down to 1.43 nM chlorpyrifos and 0.28 nM penicillin G. They even permitted the quantification of 14.3 μM chlorpyrifos and 2.8 μM penicillin G. Also, immobilization conferred higher stability to AChE (⁓94% activity after 20 days storage at 4 °C) and allowed to reuse the BL up to 12 cycles.

Microbial acoustic sensor test-system based on a piezoelectric resonator with a lateral electric field for kanamycin detection in liquid

A microbial test-system for real-time determination of low/residual concentrations of kanamycin in a liquid without the need for special labels is presented. The main element of the system was a piezoelectric resonator excited by a lateral electric field based on an X-cut lithium niobate plate 0.5 mm thick with two rectangular electrodes on one side. On the other side of the resonator, there was a 1.5 ml liquid container. As a sensory element we used Escherichia coli B-878 microbial cells, which are sensitive to kanamycin. For measurement 1 ml of this cells suspension was placed in a liquid container and then the test liquid in the amount of 2 μl containing kanamycin was added. The change in the real part of the electrical impedance of the resonator before and after the test liquid addition was used as an analytical signal which indicated the presence of kanamycin. The lower limit of determination of kanamycin turned out to be 1.0 μg/ml with an analysis time of 10 min. The test-system allows to detect kanamycin in the presence of such antibiotic as ampicillin and polymixin.

Selective and fast removal and determination of β-lactam antibiotics in aqueous solution using multiple templates imprinted polymers based on magnetic hybrid carbon material

Selective and fast adsorption of five broad-spectrum β-lactam antibiotics included amoxicillin, cephalexin, cefazolin, penicillin G and oxacillin was achieved by novel surface molecular imprinting polymers (MIPs) with magnetic hybrid carbon material as the substrate. The characteristics of MIPs were studied by scanning electron microscope, Fourier transform infrared spectrometer, thermogravimetric analysis, etc. And through a series of adsorption experiments to examine the kinetics, isotherms, thermodynamics, selectivity and reusability for sorption of β-lactam antibiotics onto the MIPs. The adsorption equilibriums were accomplished in about 60 min with adsorption capacities of 4.57-24.55 mg g^-1, while the adsorption process was preferably fitted with pseudo-second-order kinetic model and Freundlich model. The imprinting factors ranged from 1.88 to 9.94 indicated the MIPs possessed excellent recognition ability, and its good reusability was demonstrated after five times adsorption-desorption cycles without a large drop in adsorption capacity. Furthermore, a new detection method was developed by combining of MIPs with solid phase extraction and high performance liquid chromatography (MIPs-SPE-HPLC). Under the optimal SPE conditions, the limits of detection (LODs) for the five BLAs were 0.24-0.56 µg L^-1, with RSDs of 0.76-5.39%. The synthesized MIPs and the proposed MIPs-SPE-HPLC method can be applied for the efficient, simultaneous separation and detection of BLAs.

Bacteria-based electro-optical platform for ampicillin detection in aquatic solutions

We have shown for the first time that it is possible to use a bacteria-based sensory system consisting of the bacterium Pseudomonas putida TSh-18 and an electro-optical sensor to detect ampicillin in the concentration range 0.5-600 μg/mL. Changes in the anisotropy of cell polarizability were detected at 900 and 2100 kHz; these represented the state of the cytoplasm and of the cell membrane, respectively. The changes indicate the quickest cell response to changes in the characteristics of the bacterial culture exposed to ampicillin. We have also shown that it is possible to monitor the ampicillin in the presence of kanamycin. In control experiments, we examined the effects of ampicillin and kanamycin on bacterial cells by phase-contrast microscopy and by standard microbiological tests on solid media. P. putida TSh-18 is recommended as a sensor system for ampicillin detection. Electro-optical analysis ensures detection of ampicillin in aquatic solutions in real-time, takes 10 min, and offers a lower limit of ampicillin detection of 0.5 μg/mL, which is lower than the European Community's maximum residue limit standards for penicillin antibiotics.

Recent advances in electrochemical sensors for amoxicillin detection in biological and environmental samples

Amoxicillin (AMX) is among the most successful antibiotics used for human therapy. It is used extensively to prevent or treat bacterial infections in humans and animals. However, the widespread distribution and excess utilization of AMX can be an environmental and health risk due to the hazardous potential associated to its pharmaceutical industries effluents. Besides, their extensive use in food animal production may result in some undesirable residues in food, e.g. meat, eggs and milk. Consequently, at high enough concentrations in biological fluids, AMX may be responsible of various diseases such as nausea, vomiting, rashes, and antibiotic-associated colitis. For this reason, the detection and quantification of amoxicillin in pharmaceuticals, biological fluids, environmental samples and foodstuffs require new electroanalytical techniques with sensitive and rapid measurement abilities. This review discusses recent advances in the development of electrochemical sensors and bio-sensors for AMX analysis in complex matrices such as pharmaceuticals, biological fluids, environmental water and foodstuffs. The main electrochemical sensors used are based on chemically modified electrodes involving carbon materials and nanomaterials, nanoparticles, polymers and biological recognition molecules.

Comparison of Dilution on Eastern Box Turtle (Terrapene carolina carolina) and Marine Toad (Rhinella marinus) Blood Parameters as Measured on a Portable Chemistry Analyzer

Biochemical testing is an important clinical tool in evaluating the physiology of reptiles and amphibians. Suitable point of care analyzers can allow for rapid delivery of results, but small patient size can inhibit sufficient sample collection. This study evaluated the utility of sample dilution with sterile distilled water as a means of biochemical evaluation when sample volume is limited. Blood was collected from 12 eastern box turtles (Terrapene carolina carolina) and 12 marine toads (Rhinella marinus) and analyzed via i-STAT CHEM8+ cartridges. Two undiluted samples and two samples diluted 1 : 1 with sterile water were evaluated immediately following collection for each animal in the study. Analytes reported in the diluted samples were limited to glucose, ionized calcium, and total carbon dioxide. The expected dilution ratio value of diluted to undiluted samples was 0.5, of which glucose in both turtles and toads was nearest. Dilution ratio values for ionized calcium, however, were higher than expected in both turtles and toads. Sample dilution is not recommended for most analytes included on the CHEM8+ cartridge due to values occurring outside the limits of detection for the analyzer. Glucose and ionized calcium values obtained on diluted samples should be interpreted with caution but may provide clinical utility in reptile and amphibian patients where sample volume is limited.

A fiber optic nanoplasmonic biosensor for the sensitive detection of ampicillin and its analogs

A novel optical immunosensor for the screening of ampicillin (Amp) residues has been developed. The biosensor is based on fiber optic particle plasmon resonance detection and uses an enhancement method called as fiber optic nanogold-linked immunosorbent assay (FONLISA) for the sensitive detection of antibiotics. A commercial antibody which had a higher affinity for ampicillin than for other β-lactam antibiotics was chosen. A surface competitive binding assay was used in which a fixed concentration of antibiotic-conjugated gold nanoparticles (AuNPs) competes with free unlabeled antibiotic molecules to measure the amount of binding with antibody molecules immobilized on an optical fiber. The synthesis of the 11-mercaptoundecanoic acid (MUA)-ampicillin conjugate facilitates the attachment of the Amp molecules to AuNPs via MUA which acts as a linker between them. This AuNP-Amp conjugate was then used for the detection of β-lactam antibiotics. The practical limit of detection obtained for Amp was 0.74 ppb (7.4 × 10^-10 g/mL) which is lower than the recommended maximum residue limit (MRL) for β-lactams. The method also shows a wide linear range of 4 orders. Its applicability to the determination of ampicillin in spiked milk samples has been demonstrated with good recovery and reproducibility. Graphical abstract.

Development of a multicomponent immunochromatographic test system for the detection of fluoroquinolone and amphenicol antibiotics in dairy products

BACKGROUND

Ciprofloxacin (CIP) and chloramphenicol (CAP) are relevant antibiotics of the fluoroquinolone (FQ) and amphenicol (AP) groups, respectively, widely used in veterinary practice and they contaminate agricultural products. In this study, a rapid and sensitive immunochromatographic assay (ICA) was developed for simultaneous detection of CIP and CAP in dairy products. The ICA was carried out in a direct competitive format using gold nanoparticles as a label.

RESULTS

The ICA developed here allowed for the detection of CIP and CAP in Triton X-100-containing buffered saline (PBST) within 15 min with instrumental detection limits of 20 pg mL^-1 and 0.5 ng mL^-1 , respectively, and with a visual detection limit of 5 ng mL^-1 for both antibiotics. The ICA showed cross-reactivity (69-160%) to 19 antibiotics in the FQ group and no cross-reactivity (<0.1%) to 2 antibiotics of the AP group. The ICA allowed detection of CIP and CAP in a panel of dairy products by employing a simple procedure of preliminary sample preparation. The detection limits for the two antibiotics were the same as in PBST. The analytical recoveries of CIP and CAP in dairy products ranged from 83% to 120%.

CONCLUSION

The analytical characteristics of the test system allow its use for the detection of antibiotics in milk and dairy products during all steps of production. © 2019 Society of Chemical Industry.

Development of a Minimally Invasive Microneedle-Based Sensor for Continuous Monitoring of β-Lactam Antibiotic Concentrations in Vivo

Antimicrobial resistance poses a global threat to patient health. Improving the use and effectiveness of antimicrobials is critical in addressing this issue. This includes optimizing the dose of antibiotic delivered to each individual. New sensing approaches that track antimicrobial concentration for each patient in real time could allow individualized drug dosing. This work presents a potentiometric microneedle-based biosensor to detect levels of β-lactam antibiotics in vivo in a healthy human volunteer. The biosensor is coated with a pH-sensitive iridium oxide layer, which detects changes in local pH as a result of β-lactam hydrolysis by β-lactamase immobilized on the electrode surface. Development and optimization of the biosensor coatings are presented, giving a limit of detection of 6.8 μM in 10 mM PBS solution. Biosensors were found to be stable for up to 2 weeks at -20 °C and to withstand sterilization. Sensitivity was retained after application for 6 h in vivo. Proof-of-concept results are presented showing that penicillin concentrations measured using the microneedle-based biosensor track those measured using both discrete blood and microdialysis sampling in vivo. These preliminary results show the potential of this microneedle-based biosensor to provide a minimally invasive means to measure real-time β-lactam concentrations in vivo, representing an important first step toward a closed-loop therapeutic drug monitoring system.

Penicillin Detection by Tobacco Mosaic Virus-Assisted Colorimetric Biosensors

The presentation of enzymes on viral scaffolds has beneficial effects such as an increased enzyme loading and a prolonged reusability in comparison to conventional immobilization platforms. Here, we used modified tobacco mosaic virus (TMV) nanorods as enzyme carriers in penicillin G detection for the first time. Penicillinase enzymes were conjugated with streptavidin and coupled to TMV rods by use of a bifunctional biotin-linker. Penicillinase-decorated TMV particles were characterized extensively in halochromic dye-based biosensing. Acidometric analyte detection was performed with bromcresol purple as pH indicator and spectrophotometry. The TMV-assisted sensors exhibited increased enzyme loading and strongly improved reusability, and higher analysis rates compared to layouts without viral adapters. They extended the half-life of the sensors from 4 - 6 days to 5 weeks and thus allowed an at least 8-fold longer use of the sensors. Using a commercial budget-priced penicillinase preparation, a detection limit of 100 µM penicillin was obtained. Initial experiments also indicate that the system may be transferred to label-free detection layouts.

Clinical on-site monitoring of ß-lactam antibiotics for a personalized antibiotherapy

An appropriate antibiotherapy is crucial for the safety and recovery of patients. Depending on the clinical conditions of patients, the required dose to effectively eradicate an infection may vary. An inadequate dosing not only reduces the efficacy of the antibiotic, but also promotes the emergence of antimicrobial resistances. Therefore, a personalized therapy is of great interest for improved patients' outcome and will reduce in long-term the prevalence of multidrug-resistances. In this context, on-site monitoring of the antibiotic blood concentration is fundamental to facilitate an individual adjustment of the antibiotherapy. Herein, we present a bioinspired approach for the bedside monitoring of free accessible ß-lactam antibiotics, including penicillins (piperacillin) and cephalosporins (cefuroxime and cefazolin) in untreated plasma samples. The introduced system combines a disposable microfluidic chip with a naturally occurring penicillin-binding protein, resulting in a high-performance platform, capable of gauging very low antibiotic concentrations (less than 6 ng ml^-1) from only 1 µl of serum. The system's applicability to a personalized antibiotherapy was successfully demonstrated by monitoring the pharmacokinetics of patients, treated with ß-lactam antibiotics, undergoing surgery.

Production of anti-amoxicillin ScFv antibody and simulation studying its molecular recognition mechanism for penicillins

The molecular recognition mechanism of an antibody for its hapten is very interesting. The objective of this research was to study the intermolecular interactions of an anti-amoxicillin antibody with penicillin drugs. The single chain variable fragment (ScFv) antibody was generated from a hybridoma cell strain excreting the monoclonal antibody for amoxicillin. The recombinant ScFv antibody showed similar recognition ability for penicillins to its parental monoclonal antibody: simultaneous recognizing 11 penicillins with cross-reactivities of 18-107%. The three-dimensional structure of the ScFv antibody was simulated by using homology modeling, and its intermolecular interactions with 11 penicillins were studied by using molecular docking. Results showed that three CDRs are involved in antibody recognition; CDR L3 Arg 100, CDR H3 Tyr226, and CDR H3 Arg 228 were the key contact amino acid residues; hydrogen bonding was the main antibody-drug intermolecular force; and the core structure of penicillin drugs was the main antibody binding position. These results could explain the recognition mechanism of anti-amoxicillin antibody for amoxicillin and its analogs. This is the first study reporting the production of ScFv antibody for penicillins and stimulation studying its recognition mechanism.

Point-of-care diagnostics for niche applications

Point-of-care or point-of-use diagnostics are analytical devices that provide clinically relevant information without the need for a core clinical laboratory. In this review we define point-of-care diagnostics as portable versions of assays performed in a traditional clinical chemistry laboratory. This review discusses five areas relevant to human and animal health where increased attention could produce significant impact: veterinary medicine, space travel, sports medicine, emergency medicine, and operating room efficiency. For each of these areas, clinical need, available commercial products, and ongoing research into new devices are highlighted.

Design of a sensitive fluorescent polarization immunoassay for rapid screening of milk for cephalexin

In this paper we describe the development of a sensitive, fast, and easily performed fluorescence polarization immunoassay for determination of cephalexin in milk. The experimental work was performed to increase sensitivity and specificity. Therefore, the structures of the tracers were varied by synthesis of both cephalexin (CEX) and cephalotin (CET) conjugates with a variety of fluorescent labels. Two rabbit antisera containing antibodies against cephalexin and cephalotin were tested in homologous and heterologous combinations with the tracers. For every working antibody-tracer combination, the analytical conditions and cross-reactivity for structural analogues-cephalosporins and other antibiotics that could also be present in milk-were determined. It was found that the highest sensitivity was achieved by use of the homologous pair CET-EDF-anti-CET antibody (limit of detection (LOD) 0.4 μg kg(-1) for standard solutions prepared in buffer), but this combination was not appropriate because of high cross-reactivity with CET. For subsequent experiments, therefore, CEX- EDF-anti-CEX antibody were chosen (LOD 0.8 μg kg(-1) for standard solutions prepared in buffer). Part of this manuscript is devoted to the variation of precipitation agents for pretreatment of milk before analysis; milk is an extremely complicated matrix. The optimum protein precipitation agent was methanol. This technique for cephalexin determination was characterized by a limit of detection of 1 μg kg(-1). The method was validated by using naturally contaminated and spiked milk samples. The results obtained corresponded very well with those obtained by HPLC, which was used as confirmation method.

Novel Penicillin Analogues as Potential Antimicrobial Agents; Design, Synthesis and Docking Studies

A number of penicillin derivatives (4a-h) were synthesized by the condensation of 6-amino penicillinic acid (6-APA) with non-steroidal anti-inflammatory drugs as antimicrobial agents. In silico docking study of these analogues was performed against Penicillin Binding Protein (PDBID 1CEF) using AutoDock Tools 1.5.6 in order to investigate the antimicrobial data on structural basis. Penicillin binding proteins function as either transpeptidases or carboxypeptidases and in few cases demonstrate transglycosylase activity in bacteria. The excellent antibacterial potential was depicted by compounds 4c and 4e against Escherichia coli, Staphylococcus epidermidus and Staphylococcus aureus compared to the standard amoxicillin. The most potent penicillin derivative 4e exhibited same activity as standard amoxicillin against S. aureus. In the enzyme inhibitory assay the compound 4e inhibited E. coli MurC with an IC₅₀ value of 12.5 μM. The docking scores of these compounds 4c and 4e also verified their greater antibacterial potential. The results verified the importance of side chain functionalities along with the presence of central penam nucleus. The binding affinities calculated from docking results expressed in the form of binding energies ranges from -7.8 to -9.2kcal/mol. The carboxylic group of penam nucleus in all these compounds is responsible for strong binding with receptor protein with the bond length ranges from 3.4 to 4.4 Ǻ. The results of present work ratify that derivatives 4c and 4e may serve as a structural template for the design and development of potent antimicrobial agents.

Solar photocatalytic oxidation of recalcitrant natural metabolic by-products of amoxicillin biodegradation

The contamination of the aquatic environment by non-metabolized and metabolized antibiotic residues has brought the necessity of alternative treatment steps to current water decontamination technologies. This work assessed the feasibility of using a multistage treatment system for amoxicillin (AMX) spiked solutions combining: i) a biological treatment process using an enriched culture to metabolize AMX, with ii) a solar photocatalytic system to achieve the removal of the metabolized transformation products (TPs) identified via LC-MS, recalcitrant to further biological degradation. Firstly, a mixed culture (MC) was obtained through the enrichment of an activated sludge sample collected in an urban wastewater treatment plant (WWTP). Secondly, different aqueous matrices spiked with AMX were treated with the MC and the metabolic transformation products were identified. Thirdly, the efficiency of two solar assisted photocatalytic processes (TiO2/UV or Fe(3+)/Oxalate/H2O2/UV-Vis) was assessed in the degradation of the obtained TPs using a lab-scale prototype photoreactor equipped with a compound parabolic collector (CPC). Highest AMX specific biodegradation rates were obtained in buffer and urban wastewater (WW) media (0.10 ± 0.01 and 0.13 ± 0.07 g(AMX) g(biomass)(-1) h(-1), respectively). The resulting TPs, which no longer presented antibacterial activity, were identified as amoxicilloic acid (m/z = 384). The performance of the Fe(3+)/Oxalate/H2O2/UV-Vis system in the removal of the TPs from WW medium was superior to the TiO2/UV process (TPs no longer detected after 40 min (QUV = 2.6 kJ L(-1)), against incomplete TPs removal after 240 min (QUV = 14.9 kJ L(-1)), respectively).

Piezoelectric immunosensors for the detection of individual antibiotics and the total content of penicillin antibiotics in foodstuffs

Piezoelectric immunosensors on the basis of homologous and group-specificantibodies have been developed for detecting penicillin G, ampicillin, and the total content of penicillin antibiotics. The receptor coating of the sensor was obtained by the immobilization of penicillin G or ampicillin hapten-protein conjugates on the polypyrrole film obtained by electropolymerization and activated by glutaraldehyde. The affinity constants and the cross reactivity coefficients have been calculated. This made it possible to estimate the affinity and specificity of the polyclonal and monoclonal antibodies used. The calibration curves are linear in the range of concentrations 2.5-250.0 ng ml(-1) (penicillin G), 2.5-500.0 ng ml(-1) (ampicillin), and 1-500 ng ml(-1) (group of penicillin). The limits of detection are 0.8 ng ml(-1), 3.9 ng ml(-1), which are lower than MRL, established for penicillin antibiotics. The sensors were tested in detecting penicillins in milk, pork, beef, liver.