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

A Ratiometric Fluorescent Sensor for Penicillin G Based on Color-Tunable Gold-Silver Nanoclusters

Excessive administration of penicillin G and improper disposal of its residues pose a serious risk to human health; therefore, the development of convenient methods for monitoring penicillin G levels in products is essential. Herein, novel gold-silver nanoclusters (AuAgNCs) were synthesized using chicken egg white and 6-aza-2-thiothymine as dual ligands with strong yellow fluorescence at 509 and 689 nm for the highly selective detection of penicillin G. The AuAgNCs were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, ultraviolet-visible absorption spectrophotometry, and fluorescence spectrophotometry. Under optimum conditions, the fluorescence intensity decreased linearly with the concentration of penicillin G from 0.2 to 6 μM, with a low detection limit of 18 nM. Real sample analyses indicated that a sensor developed using the AuAgNCs could detect penicillin G in urine and water samples within 10 min, with the recoveries ranging from 99.7 to 104.0%. The particle size of the AuAgNCs increased from 1.80 to 9.06 nm in the presence of penicillin G. We believe the aggregation-induced quenching of the fluorescence of the AuAgNCs was the main mechanism for the detection of penicillin G. These results demonstrate the ability of our sensor for monitoring penicillin G levels in environmental and clinic samples.

Bulk and Surface Acoustic Wave Biosensors for Milk Analysis

Milk and dairy products are common foods and, therefore, are subject to regular controls. Such controls cover both the identification and quantification of specific components and the determination of physical parameters. Components include the usual milk ingredients, mainly carbohydrates, proteins, and fat, and any impurities that may be present. The latter range from small molecules, such as drug residues, to large molecules, e.g., protein-based toxins, to pathogenic microorganisms. Physical parameters of interest include viscosity as an indicator of milk gelation. Bulk and surface acoustic wave sensors, such as quartz crystal microbalance (QCM) and surface acoustic wave (SAW) devices, can principally be used for both types of analysis, with the actual application mainly depending on the device coating and the test format. This review summarizes the achievements of acoustic sensor devices used for milk analysis applications, including the determination of physical liquid parameters and the detection of low- and high-molecular-weight analytes and microorganisms. It is shown how the various requirements resulting from the respective analytes and the complex sample matrix are addressed, and to what extent the analytical demands, e.g., with regard to legal limits, are met.

Hybrid Porous Crystalline Materials from Metal Organic Frameworks and Covalent Organic Frameworks

Two frontier crystalline porous framework materials, namely, metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely explored owing to their outstanding physicochemical properties. While each type of framework has its own intrinsic advantages and shortcomings for specific applications, combining the complementary properties of the two materials allows the engineering of new classes of hybrid porous crystalline materials with properties superior to the individual components. Since the first report of MOF/COF hybrid in 2016, it has rapidly evolved as a novel platform for diverse applications. The state-of-art advances in the various synthetic approaches of MOF/COF hybrids are hereby summarized, together with their applications in different areas. Perspectives on the main challenges and future opportunities are also offered in order to inspire a multidisciplinary effort toward the further development of chemically diverse, multi-functional hybrid porous crystalline materials.

Europium chelate-labeled lateral flow assay for rapid and multiple detection of β-lactam antibiotics by the penicillin-binding protein

For the multiple and rapid detection of β-lactams, the broadly specific penicillin-binding protein (PBP) that recognizes the β-lactam structure was prepared. A chromatographic strip based on europium chelate-loaded fluorescent microspheres was assembled with a goat anti-mouse antibody (C line) and penicillin coating (T line). The penicillin coating competes with free β-lactam antibiotics to bind PBP-labeled fluorescent microspheres. The strip can theoretically detect all kinds of β-lactams, including amoxicillin, ampicillin, oxacillin, ceftazidime, lenampicillin, cefoperazone, sultamicillin, cefotaxime, ceftriaxone, sulbenicillin, piperacillin, cephalothin, flucloxacillin, and mezlocillin, in samples within 10 min. The europium chelate-labeled lateral flow assay does not cross-react with other antibiotics, including chloramphenicol, tetracycline, sulfamethazine, enrofloxacin, gentamicin or lincomycin. In short, we developed a very useful method for preliminary screening of β-lactams.

An impedimetric aptasensor for ultrasensitive detection of Penicillin G based on the use of reduced graphene oxide and gold nanoparticles

The authors describe an impedimetric aptasensor for Penicillin G (PEN) which is an important antibiotic. The method is based on the use of a pencil graphite electrode (PGE) modified with reduced graphene oxide (RGO) and gold nanoparticles (GNPs) for ultrasensitive detection of PEN. The morphology of a bare PGE, RGO/PGE, and GNP/RGO/PGE, and the functional groups on graphene oxide (GO) and RGO were studied using scanning electron microscopy and Fourier transform infrared spectroscopy. Electrochemical impedance spectroscopy was used for detection of PEN by measuring the charge transfer resistance (R_ct). Also, cyclic voltammetry was recorded at potential range of 0.30 to +0.70 V for PGE treatment. This aptamer-based assay has a wide linear range that extends from 1.0 fM to 10 μM, and a limit of detection as low as 0.8 fM. The method was applied to the determination of PEN in spiked milk from cow, sheep, goat and water buffalo. Recoveries ranged from 92% to 104%. The assay is fast, ultrasensitive, high reproducible, and selective over antibiotics such as streptomycin, tetracycline, and sulfadiazine. Graphical abstract Schematic presentation of an impedimetric aptasensor for Penicillin G antibiotic using a pencil graphite electrode (PGE) modified with reduced graphene oxide (RGO) and gold nanoparticles (GNPs). This aptamer based assay has limit of detection as low as 0.8 fM.

Electrochemical Immunosensors for Antibiotic Detection

Antibiotics are an important class of drugs destined for treatment of bacterial diseases. Misuses and overuses of antibiotics observed over the last decade have led to global problems of bacterial resistance against antibiotics (ABR). One of the crucial actions taken towards limiting the spread of antibiotics and controlling this dangerous phenomenon is the sensitive and accurate determination of antibiotics residues in body fluids, food products, and animals, as well as monitoring their presence in the environment. Immunosensors, a group of biosensors, can be considered an attractive tool because of their simplicity, rapid action, low-cost analysis, and especially, the unique selectivity arising from harnessing the antigen-antibody interaction that is the basis of immunosensor functioning. Herein, we present the recent achievements in the field of electrochemical immunosensors designed to determination of antibiotics.

Multiplex detection of quality indicator molecule targets in urine using programmable hairpin probes based on a simple double-T type microchip electrophoresis platform and isothermal polymerase-catalyzed target recycling

Recently, it has been crucial to be able to detect and quantify small molecular targets simultaneously in biological samples. Herein, a simple and conventional double-T type microchip electrophoresis (MCE) based platform for the multiplex detection of quality indicator molecule targets in urine, using ampicillin (AMPI), adenosine triphosphate (ATP) and estradiol (E2) as models, was developed. Several programmable hairpin probes (PHPs) were designed for detecting different targets and triggering isothermal polymerase-catalyzed target recycling (IPCTR) for signal amplification. Based on the target-responsive aptamer structure of PHP (Domain I), target recognition can induce PHP conformational transition and produce extension duplex DNA (dsDNA), assisted by primers & Bst polymerase. Afterwards, the target can be displaced to react with another PHP and initiate the next cycle. After several rounds of reaction, the dsDNA can be produced in large amounts by IPCTR. Three targets can be simultaneously converted to dsDNA fragments with different lengths, which can be separated and detected using MCE. Thus, a simple double-T type MCE based platform was successfully built for the homogeneous detection of multiplex targets in one channel. Under optimal conditions, the assay exhibited high throughput (48 samples per hour at most, not including reaction time) and sensitivity to three targets in urine with a detection limit of 1 nM (ATP), 0.05 nM (AMPI) and 0.1 nM (E2) respectively. The multiplex assay was successfully employed for the above three targets in several urine samples and combined the advantages of the high specificity of programmable hairpin probes, the excellent signal amplification of IPCTR, and the high through-put of MCE which can be employed for screening in biochemical analysis.

Novel nanoarchitecture of Co-MOF-on-TPN-COF hybrid: Ultralowly sensitive bioplatform of electrochemical aptasensor toward ampicillin

Owning to the misuse of the antibiotics in animal husbandry and agriculture, it is highly urgent to determine the quantification of antibiotics in biological systems by the simple, sensitive, and fast method. In this work, a novel nanoarchitecture of Co-based metal-organic frameworks (Co-MOF) and terephthalonitrile-based covalent organic framework (TPN-COF) was synthesized (represented by Co-MOF@TPN-COF), followed by the exploitation as the bioplatform of non-label aptasensor for detecting the most frequently used β-lactam antibiotics, ampicillin (AMP). The new porous hybrid material of Co-MOF@TPN-COF was synthesized by adding the as-prepared TPN-COF into the Co-MOF preparation system. The multilayered Co-MOF@TPN-COF nanosheets exhibit a high specific surface area (52.64 m² g^-1), nitrogen-rich groups and excellent electrochemical activity. As a result, large amounts of aptamer strands can be bound over the Co-MOF@TPN-COF nanosheets owning to the strong π-π stacking and hydrogen bonds. When detecting AMP by the electrochemical impedance spectroscopy, the fabricated Co-MOF@TPN-COF-based aptasensor exhibits an ultra-low detection limit of 0.217 fg mL^-1 within the AMP concentration from 1.0 fg mL^-1 to 2.0 ng mL^-1, which was superior to those previously reported in literatures. In addition, this proposed aptasensor also shows high selectivity, good reproducibility and stability, acceptable regenerability, and favorable applicability in human serum, river water and milk. Therefore, the proposed Co-MOF@TPN-COF-based aptasensor has a great promise to be applied as a powerful tool in the fields of food safety.

Electrochemical behaviour of several penicillins at high potential

Successful penicillin detection on a boron-doped diamond electrode from real environmental, biomedical and pharmaceutical samples by DPV and flow analysis.