Rapid immunochemical analysis of the sulfonamide-sugar conjugated fraction of antibiotic contaminated honey samples

Development of a molecularly imprinted membrane for selective, high-sensitive, and on-site detection of antibiotics in waters and drugs: Application for sulfamethoxazole

Sulfonamides are among the widespread bacterial antibiotics. Despite this, their quick emergence constitutes a serious problem for ecosystems and human health. Therefore, there is an increased interest in developing relevant detection method for antibiotics in different matrices. In this work, a straightforward, green, and cost-effective protocol was proposed for the preparation of a selective molecularly imprinted membrane (MIM) of sulfamethoxazole (SMX), a commonly used antibiotic. Thus, cellulose acetate was used as the functional polymer, while polyethylene glycol served as a pore-former. The developed MIM was successfully characterized through scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The MIM was used as a sensing platform in conjunction with a smartphone for optical readout, enabling on-site, selective, and highly sensitive detection of SMX. In this way, a satisfactory imprinting factor of around 3.6 and a limit of detection of 2 ng mL-1 were reached after applying response surface methodologies, including Box-Behnken and central composite designs. Besides, MIM demonstrated its applicability for the accurate and selective detection of SMX in river waters, wastewater, and drugs. Additionally, the MIM was shown to be a valuable sorbent in a solid-phase extraction protocol, employing a spin column setup that offered rapid and reproducible results. Furthermore, the developed sensing platform exhibited notable regeneration properties over multiple cycles and long shelf-life in different storage conditions. The newly developed methodology is of crucial importance to overcome the limitations of classical imprinting polymers. Furthermore, the smartphone-based platform was used to surpass the typically expensive and complicated methods of detection.

Environmentally friendly analysis of sulphonamides in Brazilian honey through automated and miniaturised sample preparation coupled with LC-MS/MS

Increased use of environmentally friendly practices has become a trend in science because of the current awareness regarding climate change and related issues. Similarly for analytical chemistry, considering the development of greener methods for reducing the use of reagents and samples and also toxic waste generation. To meet such goals, automation, and miniaturisation of sample preparation-a well-recognised laborious and time-consuming analytical step-are two promising strategies. This work associates the greener aspects of miniaturisation and the performance of automated sample preparation. Therefore, we proposed an analytical method using a miniaturised extraction column for pre-concentrating sulphamerazine, sulphamethazine, sulphamethoxazole, sulphadimethoxine, sulphathiazole, and sulphachlorpyridazine from honey and cleaning-up the samples. Several variables were optimised: extractive phase, loading flow, loading phase, and loading time. Under optimised conditions, the method showed adequate linearity between 5.0 and 60 ng g^-1 with R > 0.99, and also good selectivity and recovery (114.6-124.1%) which are acceptable according to Brazilian legislation. Intra and inter-day precision were in the range 3.0-5.0%. Although sulphonamides were detected in one of the eight commercial honey samples, the value was below the established MRL. The method showed efficiency, while also exhibiting greener characteristics resulting from miniaturisation and automation, representing a promising environmentally friendly alternative for conventional sample preparation methods.

Phages in Therapy and Prophylaxis of American Foulbrood - Recent Implications From Practical Applications

American foulbrood is one of the most serious and yet unsolved problems of beekeeping around the world, because it causes a disease leading to the weakening of the vitality of honey bee populations and huge economic losses both in agriculture and horticulture. The etiological agent of this dangerous disease is an extremely pathogenic spore-forming bacterium, Paenibacillus larvae, which makes treatment very difficult. What is more, the use of antibiotics in the European Union is forbidden due to restrictions related to the prevention of the presence of antibiotic residues in honey, as well as the global problem of spreading antibiotic resistance in case of bacterial strains. The only available solution is burning of entire bee colonies, which results in large economic losses. Therefore, bacteriophages and their lytic enzymes can be a real effective alternative in the treatment and prevention of this Apis mellifera disease. In this review, we summarize phage characteristics that make them a potentially useful tool in the fight against American foulbrood. In addition, we gathered data regarding phage application that have been described so far, and attempted to show practical implications and possible limitations of their usage.

Development of Novel Magneto-Biosensor for Sulfapyridine Detection

In this work, we report the development of a highly sensitive biosensor for sulfapyridine detection based on an integrated bio micro-electromechanical system (Bio-MEMS) containing four gold working electrodes (WEs), a platinum counter electrode (CE), and a reference electrode (RE). Firstly, the cleaned WEs were modified with 4-aminophenylacetic acid (CMA). Then, (5-[4-(amino)phenylsulfonamide]-5-oxopentanoic acid (SA2BSA) was immobilized onto the transducers surface by carbodiimide chemistry. The analyte was quantified by competitive detection with SA2BSA immobilized on the WE toward a mixture of Ab155 antibody (with fixed concentration) and sulfapyridine. In order to obtain a highly sensitive biosensor, Ab155 was immobilized onto magnetic latex nanoparticles surface to create a 3D architecture (Ab-MLNp). Using electrochemical impedance spectroscopy (EIS), we investigated the influence of the Ab-MLNp on the sensitivity of our approach. The optimized system was analyzed, as competitive assay, with different concentrations of sulfapyridine (40 µM, 4 µM, and 2 nM) and with phosphate buffer solution. From data fitting calculations and graphs, it was observed that the EIS showed more linearity when Ab-MLNp was used. This result indicates that the magnetic latex nanoparticles increased the sensitivity of the biosensor.

Upconversion luminescence resonance energy transfer-based aptasensor for the sensitive detection of oxytetracycline

In this work, a biosensor based on luminescence resonance energy transfer (LRET) from NaYF4:Yb,Tm upconversion nanoparticles (UCNPs) to SYBR Green I has been developed. The aptamers are covalently linked to UCNPs and hybridized with their complementary strands. The subsequent addition of SYBR Green allows SYBR Green I to insert into the formed double-stranded DNA (dsDNA) duplex and brings the energy donor and acceptor into close proximity, leading to the fluorescence of UCNPs transferred to SYBR Green I. When excited at 980 nm, the UCNPs emit luminescence at 477 nm, and this energy is transferred to SYBR Green I, which emits luminescence at 530 nm. In the presence of oxytetracycline (OTC), the aptamers prefer to bind to its corresponding analyte and dehybridize with the complementary DNA. This dehybridization leads to the liberation of SYBR Green I, which distances SYBR Green I from the UCNPs and recovers the UCNPs' luminescence. Under optimal conditions, a linear calibration is obtained between the ratio of I530 to I477 nm (I530/I477) and the OTC concentration, which ranges from 0.1 to 10 ng/ml with a limit of detection (LOD) of 0.054 ng/ml.