Enhanced Single-Particle Collision Electrochemistry at Polysulfide-Functionalized Microelectrodes for SARS-CoV-2 Detection.

Single-particle collision electrochemistry (SPCE) has shown great promise in biosensing applications due to its high sensitivity, high flux, and fast response. However, a low effective collision frequency and a large number of interfering substances in complex matrices limit its broad application in clinical samples. Herein, a novel and universal SPCE biosensor was proposed to realize sensitive detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) based on the collision and oxidation of single silver nanoparticles (Ag NPs) on polysulfide-functionalized gold ultramicroelectrodes (Ps-Au UMEs). Taking advantage of the strong interaction of the Ag-S bond, collision and oxidation of Ag NPs on the Ps-Au UME surface could be greatly promoted to generate enhanced Faraday currents. Compared with bare Au UMEs, the collision frequency of Ps-Au UMEs was increased by 15-fold, which vastly improved the detection sensitivity and practicability of SPCE in biosensing. By combining magnetic separation, liposome encapsulation release, and DNAzyme-assisted signal amplification, the SPCE biosensor provided a dynamic range of 5 orders of magnitude for spike proteins with a detection limit of 6.78 fg/mL and a detection limit of 21 TCID50/mL for SARS-CoV-2. Furthermore, SARS-CoV-2 detection in nasopharyngeal swab samples of infected patients was successfully conducted, indicating the potential of the SPCE biosensor for use in clinically relevant diagnosis.

A general controllable release amplification strategy of liposomes for single-particle collision electrochemical biosensing.

As an important component of the COVID-19 mRNA vaccines, liposomes play a key role in the efficient protection and delivery of mRNA to cells. Herein, due to the controllable release amplification strategy of liposomes, a reliable and robust single-particle collision electrochemical (SPCE) biosensor was constructed for H9N2 avian influenza virus (H9N2 AIV) detection by combining liposome encapsulation-release strategy with immunomagnetic separation. The liposomes modified with biotin and loaded with platinum nanoparticles (Pt NPs) were used as signal probes for the first time. Biotin facilitated the coupling of biomolecules (DNA or antibodies) through the specific reaction of biotin-streptavidin. Each liposome can encapsulate multiple Pt NPs, which were ruptured under the presence of 1 × PBST (phosphate buffer saline with 0.05% Tween-20) within 2 min, and the encapsulated Pt NPs were released for SPCE experiment. The combination of immunomagnetic separation not only improved the anti-interference capabilities but also avoided the agglomeration of Pt NPs, enabling the SPCE biosensor to realize ultrasensitive detection of 18.1 fg/mL H9N2 AIV. Furthermore, the reliable SPCE biosensor was successfully applied in specific detection of H9N2 AIV in complex samples (chicken serum, chicken liver and chicken lung), which promoted the universality of SPCE biosensor and its application prospect in early diagnosis of diseases.

[Head and Face Protection of the Health Care Workers in the Operating Room of Peking Union Medical College Hospital during the Corona Virus Disease-19 Pandemic].

Objective To investigate the understanding of the head and face protection of the health care workers in operating room of Peking Union Medical College Hospital during the corona virus disease-19(COVID-19) pandemic.Methods The knowledge of head and face protection of health care workers in the operating room was evaluated based on the non-registered questionnaires for protection measures collected on-line.Results The survey was conducted in two phases.In the first phase(COVID-19 outbreak),153 questionnaires were collected.In the second phase(when Beijing lowered the emergency response to level 3 and normalized the epidemic prevention and control),101 questionnaires were collected.The results showed that 98% of health care workers had used any form of protective devices during the pandemic and anesthesiologists had the highest usage rate(93.0%)of ear-loop face mask with eye shield.During the pandemic,health care workers mainly used goggles(71.2%)for protection to diagnose and treat the patients with fever and ear-loop face mask with eye shield(56.2%)for protection to diagnose and treat the non-fever patients.In the first-and second-phase survey,43% and 68% of health care workers still used protection,and they mainly used face shield(50.0% and 56.5%)and ear-loop face mask with eye shield(56.1% and 68.1%).Conclusions During the pandemic,more than 90% of the health care workers in the operating room of Peking Union Medical College Hospital were aware of head and face protection.Different healthcare workers in the operating room had different choices of head and face protection,and more than 40% of them would still keep such protection during the normalized stage of pandemic prevention and control.