Safe Elective Surgery Using Selective SARS-CoV-2 (COVID-19) Molecular Testing.

Resuming elective surgery amid shortages of rapid severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tests and personal protective equipment, while protecting patient and staff safety, posed a challenge at the study institution. Many hospital systems implemented testing of all presurgical patients, using results from tests performed 3 or more days prior to surgery. Among asymptomatic persons, the percent positive rates of coronavirus disease 2019 (COVID-19) tests in the region did not appear to justify this practice. Instead of universal preoperative COVID-19 testing, the authors elected to mitigate risk by implementing a preoperative program including 14 days of recommended patient self-quarantine and social distancing. For those unable to complete this program and for those undergoing high-risk, aerosol-generating procedures, targeted rapid polymerase chain reaction testing within 2 days of surgery was performed. Data from the initial 4 months suggests that this approach was noninferior to universal preoperative testing with regard to postoperative COVID-19 detection and patient exposure-related COVID-19 cases among hospital staff.

Labeless AC impedimetric antibody-based sensors with pgml(-1) sensitivities for point-of-care biomedical applications.

This paper describes the development and characterisation of labeless immunosensors for (a) the cardiac drug digoxin and (b) bovine serum albumin (BSA). Commercial screen-printed carbon electrodes were used as the basis for the sensors. Two methods were used to immobilise antibodies at the electrode surface. Aniline was electropolymerised onto these electrodes to form a thin planar film of conductive polyaniline; the polyaniline film was then utilised as a substrate to immobilise biotinylated anti-digoxin using a classical avidin-biotin affinity approach. As an alternative approach, poly(1,2-diaminobenzene) was electrodeposited onto the carbon electrodes and this modified surface was then sonochemically ablated to form an array of micropores. A second electropolymerisation step was then used to co-deposit conductive polyaniline along with antibodies for BSA within these pores to produce a microarray of polyaniline protrusions with diameters of several mum, containing entrapped anti-BSA. The resulting antibody grafted electrodes were interrogated using an AC impedance protocol before and following exposure to digoxin or BSA solutions, along with control samples containing a non-specific IgG antibody. The impedance characteristics of both types of electrode were changed by increasing concentrations of antigen up to a saturation level. Calibration curves were obtained by subtraction of the non-specific response from the specific response, thereby eliminating the effects of non-specific adsorption of antigen. Both the use of microelectrode arrays and affinity binding protocols showed large enhancements in sensitivity over planar electrodes containing entrapped antibodies and gave similar sensitivities to our other published work using affinity-based planar electrodes. Detection limits were in the order of 0.1ngml(-1) for digoxin and 1.5ngml(-1) for BSA.

Labeless immunosensor assay for the stroke marker protein neuron specific enolase based upon an alternating current impedance protocol.

This paper describes the development and characterization of a label-less immunosensor for neuron-specific enolase (NSE) and its interrogation using an ac impedance protocol. Commercial screen-printed carbon electrodes were used as the basis for the sensor. Poly(1,2-diaminobenzene) was electrodeposited onto the sensors--and this modified surface was then sonochemically ablated to form an array of micropores. A second electropolymerization step was then used to deposit conductive polyaniline within these pores to give a microarray of polyaniline protrusions with diameters of several mum. This array was then utilized as a substrate to immobilize a biotinylated antibody for NSE using a classical avidin-biotin approach. Electrodes containing the antibodies were exposed to solutions of NSE and interrogated using an ac impedance protocol. The real component of the impedance of the electrodes was found to increase with increasing concentration of antigen. Control samples containing a nonspecific IgG antibody were also studied and calibration curves obtained by subtraction of the responses for specific and nonspecific antibody-based sensors, thereby accounting for and eliminating the effects of nonspecific adsorption of NSE. A linear relationship between the concentration of NSE in buffer solutions from 0 to 50 pg mL(-1) and the impedimetric response was observed.

Labeless immunosensor assay for prostate specific antigen with picogram per milliliter limits of detection based upon an ac impedance protocol.

This paper describes the development of labeless immunosensors for the prostate cancer marker prostate specific antigen (PSA). Poly(1,2-diaminobenzene) was electrodeposited onto screen-printed carbon electrodes, and this modified surface was sonochemically ablated to form a microelectrode array. Polyaniline was electropolymerized within these pores to form a microarray of conductive polyaniline protrusions. Two methods were utilized to immobilize antibodies for prostate specific antigen (APSA). The first involved entrapment of APSA during electropolymerization of the polyaniline. The second utilized a polyaniline array as a substrate to immobilize a biotinylated APSA using a classical avidin-biotin affinity approach. Microelectrode arrays were interrogated using ac impedance protocols before and following exposure to PSA solutions. Our preliminary results show that concentration/ac response relationships were recorded over very different ranges; sensors fabricated using an affinity approach exhibited detection limits 1000 times lower than those formulated by the entrapment method. This demonstrates that assembly protocols have major effects on immunosensor performance.

Sonochemically fabricated microelectrode arrays for biosensors offering widespread applicability: Part I.

A novel and patented procedure is described for the sonochemical fabrication of a new class of microelectrode array based sensor with electrode element populations of up to 2 x 10(5) cm(-2). For some years it has been accepted that microelectrode arrays offer an attractive route for lowering minimum limits of detection and imparting stir (convectional mass transport) independence to sensor responses; despite this no commercial biosensors, to date, have employed microelectrode arrays, largely due to the cost of conventional fabrication routes that have not proved commercially viable for disposable devices. Biosensors formed by our sonochemical approach offer unrivalled sensitivity and impart stir independence to sensor responses. This format lends itself for mass fabrication due to the simplicity and inexpensiveness of the approach; in the first instance impedimetric and amperometric sensors are reported for glucose as model systems. Sensors already developed for ethanol, oxalate and a number of pesticide determinations will be reported in subsequent publications.