Aqueous two-phase system (ATPS) is a liquid-liquid fractionation technique and has gained an interest because of great potential for the extraction, separation, purification and enrichment of proteins, membranes, viruses, enzymes, nucleic acids and other biomolecules both in industry and academia. Although, the partition behavior involved in the method is complex and difficult to predict. Current research shows that it has also been successfully used in the detection of veterinary drug residues in food, separation of precious metals, sewage treatment and a variety of other purposes. The ATPS is able to give high recovery yield and is easily to scale up. It is also very economic and environment friendly method. The aim of this review is to overview the basics of ATPS, optimization and its applications.

Because of the high research and development cost of new drugs, the long development process of new drugs, and the high failure rate at later stages, combining past drugs has gradually become a more economical and attractive alternative. However, the ensuing problem of drug–drug interactions (DDIs) urgently need to be solved, and combination has attracted a lot of attention from pharmaceutical researchers. At present, DDI is often evaluated and investigated from two perspectives: pharmacodynamics and pharmacokinetics. However, in some special cases, DDI cannot be accurately evaluated from a single perspective. Therefore, this review describes and compares the current DDI evaluation methods based on two aspects: pharmacokinetic interaction and pharmacodynamic interaction. The methods summarized in this paper mainly include probe drug cocktail methods, liver microsome and hepatocyte models, static models, physiologically based pharmacokinetic models, machine learning models, in vivo comparative efficacy studies, and in vitro static and dynamic tests. This review aims to serve as a useful guide for interested researchers to promote more scientific accuracy and clinical practical use of DDI studies.

T-2 toxin (T-2) is one of major concern mycotoxins acknowledged as an unavoidable contaminant in human foods, animal feeds and also agriculture products. Thus, a facile and sensitive method is essential for accurate T-2 toxin detection. In our work, a specific electrochemical immunosensor based on gold nanoparticles/carboxylic group-functionalized single-walled carbon nanotubes/chitosan (AuNPs/cSWNTs/CS) composite was established. The mechanism of the electrochemical immunosensor was an indirect competitive binding to a given amount of anti-T-2 between free T-2 and T-2-bovine serum albumin, which was conjugated on covalently functionalized cSWNTs decorated on the glass carbon electrode. Afterwards, the alkaline phosphatase labeled anti-mouse secondary antibody was bound to the electrode surface by reacting with the primary antibody. Lastly, alkaline phosphatase catalyzed the hydrolysis of the substrate α-naphthyl phosphate, which produced an electrochemical signal. Compared with conventional methods, the established immunosensor was more sensitive and simpler. Under optimal conditions, this method could quantitatively detect T-2 from 0.01 to 100 μg·L⁻¹ with a detection limit of 0.13 μg·L⁻¹ and favorable recovery 91.42–102.49%. Moreover, the immunosensor was successfully applied to assay T-2 in feed and swine meat, which showed good correlation with the results obtained from liquid chromatography-tandem mass spectrometry (LC-MS/MS).

In this study, a highly sensitive monoclonal antibody (mAb) was developed for the detection of aflatoxin B₁ (AFB₁) in maize and feed. Additionally, indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and time-resolved fluorescence immunoassay assay (TRFICA) were established. Firstly, the hapten AFB₁-CMO was synthesized and conjugated with carrier proteins to prepare the immunogen for mouse immunization. Subsequently, mAb was generated using the classical hybridoma technique. The lowest half-maximal inhibitory concentration (IC50) of ic-ELISA was 38.6 ng/kg with a linear range of 6.25–100 ng/kg. The limits of detections (LODs) were 6.58 ng/kg and 5.54 ng/kg in maize and feed, respectively, with the recoveries ranging from 72% to 94%. The TRFICA was developed with a significantly reduced detection time of only 21 min, from sample processing to reading. Additionally, the limits of detection (LODs) for maize and feed were determined to be 62.7 ng/kg and 121 ng/kg, respectively. The linear ranges were 100–4000 ng/kg, with the recoveries ranging from 90% to 98%. In conclusion, the development of AFB₁ mAb and the establishment of ic-ELISA for high-throughput sample detection, as well as TRFICA for rapid detection presented robust tools for versatile AFB₁ detection in different scenarios.

In antibiotics, β-lactam is one kind of major concern acknowledged as an unavoidable contaminant in milk. Thus, a facile and sensitive method is essential for rapid β-lactam antibiotics detection. In our work, a specific electrochemical receptor sensor based on the graphene/thionine (GO/TH) composite was established. The mechanism of the electrochemical receptor sensor was a direct competitive inhibition of the binding of horseradish peroxidase-labeled ampicillin (HRP-AMP) to the mutant BlaR-CTD protein by free β-lactam antibiotics. Then, horseradish peroxidase (HRP) catalyzed the hydrolysis of the substrate hydrogen peroxide (H₂O₂), which produced an electrochemical signal. Under optimal experimental conditions, this method could quantitatively detect cefquinome from 0.1 to 8 μg L⁻¹ and with the limit of detection (LOD) of 0.16 μg L⁻¹, much lower than the maximum residue limit (MRL) of 5 μg L⁻¹ set by the European Union. In addition, the LOD of spiked milk samples with cefalexin, cefquinoxime, cefotafur, penicillin G and ampicillin were 14.88 μg L⁻¹, 2.46 μg L⁻¹, 17.16 μg L⁻¹, 0.06 μg L⁻¹, 0.21 μg L⁻¹ and the limits of quantitation (LOQ) were 36.09 μg L⁻¹, 5.40 μg L⁻¹, 41.45 μg L⁻¹, 0.13 μg L⁻¹, 0.42 μg L⁻¹, respectively. The sensor showed a favorable recovery of 84.89–102.44%. Moreover, the electrochemical receptor sensor was successfully applied to assay β-lactam antibiotics in milk, which showed good correlation with the results obtained from liquid chromatography-tandem mass spectrometry (LC-MS/MS).