A novel aptamer biosensor for fast tetracyclines determination was established and illustrated in this paper. The tetracyclines aptamer as a specific affinity molecule was immobilized on the surface of the glassy carbon (GC) electrodes. It can specifically bind tetracyclines quickly in milk and other samples without sample treatment. Subsequently, the electrochemical signals are produced and measured accurately. The linear relationship between the currents and the tetracyclines concentration is 0.1–100ng ml⁻¹. The sensitivity limit of the device is 1ng ml⁻¹. The detection time is 5 min.

Microalgae have been considered as a promising biomass for biofuel production, but freshwater resource consumption during the scaled-up cultivation are still a challenge. Obtaining robust marine strains capable of producing triacylglycerols and high value-added metabolites are critical for overcoming the limitations of water resources and economical feasibility. In this study, a marine microalga with lipid and astaxanthin accumulation capability was isolated from Bohai Bay, China. The alga was named as Coelastrum sp. HA-1 based on its morphological and molecular identification. The major characteristics of HA-1 and the effects of nitrogen on its lipid and astaxanthin accumulations were investigated. Results indicated that the highest biomass, lipid and astaxanthin yields achieved were 50.9 g m⁻² day⁻¹, 18.0 g m⁻² day⁻¹ and 168.9 mg m⁻² day⁻¹, respectively, after cultivation for 24 days. The fatty acids of HA-1, identified in their majority as oleic acid (56.6%) and palmitic acid (25.9%), are desirable biofuel feedstocks. In addition, this alga can be harvested with simple sedimentation, achieving 98.2% removal efficiency after settling for 24 h. These results suggest that Coelastrum sp. HA-1 has several desirable key features that make it a potential candidate for biofuel production.

A novel aptamer nano-porous silicon (PS) biosensor was investigated for the rapid determination of tetracyclines. Electrochemical impedance spectroscopy (EIS) was used to analyze the behavior of the sensor. The specific binding of tetracycline to the aptamer biosensor led to a decrease in impedance. The corresponding impedance spectra (Nyquist plots) were obtained when serial concentrations of tetracycline were added into the system. An equivalent electrical circuit was used to fit the impedance data. The linear range of the sensor was 2.1–62.4 nM.