In this work, an “off–on” photoelectrochemical sensing strategy for the determination of trace kanamycin is proposed by using a kanamycin aptamer as the sensing unit, gold nanoparticles (AuNPs) and polypyrrole as the signal amplification unit and cerium dioxide as the photoelectric active material. The proposed method has a good linear range from 0.5–200 μg L−1 with a detection limit of 0.2 μg L−1 (S/N = 3). The present aptasensor showed excellent specificity and high sensitivity when it was used to determine the amount of kanamycin in milk and kanamycin sulfate injection.

In this work, three-dimensional (3D) hyperbranched TiO2 nanorod arrays were synthesized and used to fabricate dopamine sensitized photoelectrochemical (PEC) biosensor. To increase the lifetime of charge carriers and enhance the photocurrent responses signal, a delicate signal amplification strategy by introducing dopamine (DA) as sensitizer was developed. The dopamine sensitized TiO2 can shorten the carrier diffusion distance, improve light harvesting efficiency and charge collection efficiency, which results in performance improvement of the as-obtained PEC sensor. This proposed biosensor for determination of neuron specific enolase (NSE) demonstrated a good linear relationship range from 0.1 ng mL−1 to 1000 ng mL−1 with a detection limit of 0.05 ngmL−1 (S/N = 3). In addition, the as-prepared immunosensor exhibits excellent selectivity, stability and reproducibility, which could be extended to other label-free sensing fields. Therefore, this proposed method may also provide potential applications for the clinical examination.

A highly sensitive and selective method was developed for the simultaneous determination of eleven volatile N-nitrosamines (VNAs) in skin care cosmetics by ultrasonic-assisted extraction, coupled with multi-walled carbon nanotube (MWCNT) purification and ultrahigh-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (UPLC-APCI/MS/MS). In order to improve the sensitivity of the developed method, the systematic optimization of the sample pretreatment was carried out, including the type and amount of adsorbent and the adsorption time. The final optimal extraction procedure involved 50 mg MWCNT (7–15 nm), 1.5 mL sample extracting solution (1.0 g homogenized sample was extracted by 10 mL acetonitrile), and dispersive adsorption for 20 min. Then, the purified analytes were well separated and quantified by UPLC-APCI/MS/MS, using the isotope dilution method. The method was validated using spiked samples of two different skin care cosmetics. The recoveries were between 89% and 128%, with relative standard deviation (RSD) values of 5–26% for intra-day precision and <30% for inter-day precision. The limits of detection (LOD) of the developed method ranged from 7 μg kg−1 to 250 μg kg−1 for eleven target VNAs. Method applicability and reliability were tested by the analysis of different skin care cosmetics. The results showed that one of the skin care cosmetics had a relatively low content of N-nitrosodibenzylamine (NDBzA).

Samarium doped cerium dioxide (CSO) nanostructures possessing a shell-like morphology were synthesised by a simple hydrothermal method. A novel nanocomposite membrane, comprising of CSO nanostructures, chitosan (CH) and a room temperature ionic liquid (RTIL) was deposited onto an indium-tin oxide (ITO) electrode for developing a DNA biosensor related to the breast cancer gene. The properties of the CSO and nano-composite membrane were studied by thermogravimetry (TG), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization capacity of the DNA biosensor was studied by differential pulse voltammetry (DPV) using [Fe(CN)6]3−/4− as an indicator. Under optimal conditions, the fabricated DNA biosensor could quantify a wide range of target DNA concentrations over the range of 1 × 10−13 to 1 × 10−6 M with good linearity (R = 0.9981) and a low detection limit of 1.56 × 10−14 M (3σ). Results showed that the fabricated shell-like CSO nanostructures and RTIL could enhance the electrical conductivity synergistically, which has great potential application in sensitive electrochemical biosensors.

Samarium doped cerium dioxide (CSO) nanostructures possessing a shell-like morphology were synthesised by a simple hydrothermal method. A novel nanocomposite membrane, comprising of CSO nanostructures, chitosan (CH) and a room temperature ionic liquid (RTIL) was deposited onto an indium-tin oxide (ITO) electrode for developing a DNA biosensor related to the breast cancer gene. The properties of the CSO and nano-composite membrane were studied by thermogravimetry (TG), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization capacity of the DNA biosensor was studied by differential pulse voltammetry (DPV) using [Fe(CN)6]3−/4− as an indicator. Under optimal conditions, the fabricated DNA biosensor could quantify a wide range of target DNA concentrations over the range of 1 × 10−13 to 1 × 10−6 M with good linearity (R = 0.9981) and a low detection limit of 1.56 × 10−14 M (3σ). Results showed that the fabricated shell-like CSO nanostructures and RTIL could enhance the electrical conductivity synergistically, which has great potential application in sensitive electrochemical biosensors.