An ultrasensitive electrochemiluminescence (ECL) biosensor was proposed based on a closed bipolar electrode (BPE) for the detection of alkaline phosphatase (ALP). For most of the BPE–ECL biosensors, an effective signal amplification strategy was the key to enhance the sensitivity of the system. Herein, the signal amplification strategy of the enzyme catalysis was utilized in the BPE–ECL system. Au nanoparticles (NPs) were electrodeposited on the cathode surface of the ITO electrode to improve the stability and sensitivity of the signal. Compared with the previous BPE–ECL biosensors, the sensitivity was increased by at least 3 orders of magnitude. The biosensor showed high sensitivity and specificity of ALP detection with a detection limit of as low as 3.7 aM. Besides, it was further applied to the detection of ALP in different types of cells and successfully realized ALP detection in single Hep G2 cell, which had a huge application prospect in single biomolecule detection or single cell analysis.

Single-nanoparticle collision electrochemistry (SNCE) has gradually become an attractive analytical method due to its advantages in analytical detection, such as a fast response, low cost, low sample consumption, and in situ real-time detection of analytes. However, the biological analyte's direct detection based on the SNCE blocking mode has the problems of low sensitivity and specificity. In this work, an SNCE biosensor based on SNCE electrocatalytic strategy was used for the detection of H7N9 AIV. Nucleic acid aptamers were introduced to recognize the target virus (H7N9 AIV). After the recognition event, ssDNA 1 was released and hybridized with another ssDNA 2 . Owing to the nicking endonuclease Nt.AlwI-mediated target nucleic acid cyclic amplification, one virus particle can indirectly induce the release of 4.2 × 10 6 Au NPs that can be counted by the SNCE electrocatalytic strategy. The high conversion efficiency greatly improved the detection sensitivity, and the detection limit was as low as 24.3 fg/mL. Therefore, the constructed biosensor can achieve a highly sensitive and specific detection of H7N9 AIV and show a great potential in bioanalytical application.

Among the numerous forms of cancer immunotherapy, cancer vaccines have attracted increasing attention because of their ability to elicit sustained antitumor immune responses and durable tumor regression. Here, a personalized...