Addressing Signal Drift and Screening for Detection of Biomarkers with Carbon Nanotube Transistors.

Electrical biosensors, including transistor-based devices (i.e., BioFETs), have the potential to offer versatile biomarker detection in a simple, low-cost, scalable, and point-of-care manner. Semiconducting carbon nanotubes (CNTs) are among the most explored nanomaterial candidates for BioFETs due to their high electrical sensitivity and compatibility with diverse fabrication approaches. However, when operating in solutions at biologically relevant ionic strengths, CNT-based BioFETs suffer from debilitating levels of signal drift and charge screening, which are often unaccounted for or sidestepped (but not addressed) by testing in diluted solutions. In this work, we present an ultrasensitive CNT-based BioFET called the D4-TFT, an immunoassay with an electrical readout, which overcomes charge screening and drift-related limitations of BioFETs. In high ionic strength solution (1X PBS), the D4-TFT repeatedly and stably detects subfemtomolar biomarker concentrations in a point-of-care form factor by increasing the sensing distance in solution (Debye length) and mitigating signal drift effects. Debye length screening and biofouling effects are overcome using a poly(ethylene glycol)-like polymer brush interface (POEGMA) above the device into which antibodies are printed. Simultaneous testing of a control device having no antibodies printed over the CNT channel confirms successful detection of the target biomarker via an on-current shift caused by antibody sandwich formation. Drift in the target signal is mitigated by a combination of: (1) maximizing sensitivity by appropriate passivation alongside the polymer brush coating; (2) using a stable electrical testing configuration; and (3) enforcing a rigorous testing methodology that relies on infrequent DC sweeps rather than static or AC measurements. These improvements are realized in a relatively simple device using printed CNTs and antibodies for a low-cost, versatile platform for the ongoing pursuit of point-of-care BioFETs.

A gravity-driven droplet fluidic point-of-care test.

We report a simple droplet fluidic point-of-care test (POCT) that uses gravity to manipulate the sequence, timing, and motion of droplets on a surface. To fabricate this POCT, we first developed a surface coating toolbox of nine different coatings with three levels of wettability and three levels of slipperiness that can be independently tailored. We then fabricated a device that has interconnected fluidic elements-pumps, flow resistors and flow guides-on a highly slippery solid surface to precisely control the timing and sequence of motion of multiple droplets and their interactions on the surface. We then used this device to carry out a multi-step enzymatic assay of a clinically relevant analyte-lactate dehydrogenase (LDH)-to demonstrate the application of this technology for point-of-care diagnosis.

COVID-19 Diagnosis and SARS-CoV-2 Strain Identification by a Rapid, Multiplexed, Point-of-Care Antibody Microarray.

Antigen tests to detect SARS-CoV-2 have emerged as a promising rapid diagnostic method for COVID-19, but they are unable to differentiate between variants of concern (VOCs). Here, we report a rapid point-of-care test (POC-T), termed CoVariant-SPOT, that uses a set of antibodies that are either tolerant or intolerant to spike protein mutations to identify the likely SARS-CoV-2 strain concurrent with COVID-19 diagnosis using antibodies targeting the nucleocapsid protein. All reagents are incorporated into a portable, multiplexed, and sensitive diagnostic platform built upon a nonfouling polymer brush. To validate CoVariant-SPOT, we tested recombinant SARS-CoV-2 proteins, inactivated viruses, and nasopharyngeal swab samples from COVID-19 positive and negative individuals and showed that CoVariant-SPOT can readily distinguish between two VOCs: Delta and Omicron. We believe that CoVariant-SPOT can serve as a valuable adjunct to next-generation sequencing to rapidly identify variants using a scalable and deployable POC-T, thereby enhancing community surveillance efforts worldwide and informing treatment selection.

Intraluminal oxygen mitigates acute mesenteric ischaemia: a systematic review of methods and outcomes in animal studies.

BACKGROUND: Acute Mesenteric Ischaemic (AMI) is a rare condition with significant morbidity and mortality. Many causes of AMI exist, which usually begin with mucosal injury. Onset is insiduous and there is frequent diagnostic delay. Current treatments can only control established injury and prevent propagation, hence new interventions are needed. The prevention and treatment of AMI by intraluminal delivery of oxygen has yet to be investigated in the clinical setting. This article aims to systemically review experimental studies investigating this novel therapy. METHODS: Following the PRISMA guidelines, searches of PubMed and Ovid MEDLINE databases were performed up to June 2022. Two independent investigators extracted the data. RESULTS: There were 20 experimental studies, 16 of which used an occlusive ischaemia reperfusion model. Six different formulations were used to deliver intraluminal oxygen, with perflurocarbon being the most common. Studies consistently showed local and systemic benefits. Intraluminal oxygen therapy improved histological severity of mucosal injury in all studies when oxygen was delivered during the ischaemia phase, but could cause harm if given during the reperfusion phase. Improvement was also demonstrated in endpoints assessing intestinal function, biomarkers of intestinal damage, measures of systemic physiological derangement and mortality. CONCLUSION: Intraluminal oxygenation appears to be an effective treatment for AMI. There remain significant questions regarding optimal timing and delivery formulation before clinical translation of this treatment strategy.

Smartphone Enabled Point-of-Care Detection of Serum Biomarkers.

Sandwich immunoassays are the gold standard for detection of protein analytes. Here, we describe an ultrasensitive point-of-care sandwich immunoassay platform for the detection of biomarkers directly from blood or serum using a custom-built smartphone detector. Testing undiluted blood or serum is challenging due to the complexity of the matrix. Proteins nonspecifically adsorb to and cells often adhere to the assay surface, which can drastically impact the analytical sensitivity of the assay. To address this problem, our assay is built upon a "nonfouling" polymer brush "grafted from" a glass slide, which eliminates nearly all nonspecific binding and therefore increases the signal-to-noise ratio and greatly improves the analytical performance of the test. The two components required to perform a sandwich immunoassay are inkjet-printed directly onto the surface: (1) "stable" capture antibodies that remain entrapped in the brush even after exposure to a liquid sample and (2) fluorescently labeled "soluble" detection antibodies that dissolve upon exposure to a liquid sample. The polymer brush provides hydration to the antibodies, allowing them to remain stable and active over prolonged periods of time. When a liquid sample containing a biomarker of interest is dispensed onto the chip, the detection antibodies dissolve and diffuse to the stable capture spots forming a complex that sandwiches the analyte and that has a fluorescence intensity proportional to the concentration of the biomarker in solution, which can be measured using a custom-built smartphone detector. As multiple capture antibodies can be printed as discrete capture spots, the assay can be easily multiplexed without the need for multiple fluorophores. This chip and detector platform can be utilized for the point-of-care detection of low-abundance biomarkers directly from blood or serum in low-resource settings.

Rapid test to assess the escape of SARS-CoV-2 variants of concern.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants are concerning in the ongoing coronavirus disease 2019 (COVID-19) pandemic. Here, we developed a rapid test, termed CoVariant-SCAN, that detects neutralizing antibodies (nAbs) capable of blocking interactions between the angiotensin-converting enzyme 2 receptor and the spike protein of wild-type (WT) SARS-CoV-2 and three other variants: B.1.1.7, B.1.351, and P.1. Using CoVariant-SCAN, we assessed neutralization/blocking of monoclonal antibodies and plasma from COVID-19­positive and vaccinated individuals. For several monoclonal antibodies and most plasma samples, neutralization against B.1.351 and P.1 variants is diminished relative to WT, while B.1.1.7 is largely cross-neutralized. We also showed that we can rapidly adapt the platform to detect nAbs against an additional variant­B.1.617.2 (Delta)­without reengineering or reoptimizing the assay. Results using CoVariant-SCAN are consistent with live virus neutralization assays and demonstrate that this easy-to-deploy test could be used to rapidly assess nAb response against multiple SARS-CoV-2 variants.

Cellphone enabled point-of-care assessment of breast tumor cytology and molecular HER2 expression from fine-needle aspirates.

Management of breast cancer in limited-resource settings is hindered by a lack of low-cost, logistically sustainable approaches toward molecular and cellular diagnostic pathology services that are needed to guide therapy. To address these limitations, we have developed a multimodal cellphone-based platform-the EpiView-D4-that can evaluate both cellular morphology and molecular expression of clinically relevant biomarkers directly from fine-needle aspiration (FNA) of breast tissue specimens within 1 h. The EpiView-D4 is comprised of two components: (1) an immunodiagnostic chip built upon a "non-fouling" polymer brush-coating (the "D4") which quantifies expression of protein biomarkers directly from crude cell lysates, and (2) a custom cellphone-based optical microscope ("EpiView") designed for imaging cytology preparations and D4 assay readout. As a proof-of-concept, we used the EpiView-D4 for assessment of human epidermal growth factor receptor-2 (HER2) expression and validated the performance using cancer cell lines, animal models, and human tissue specimens. We found that FNA cytology specimens (prepared in less than 5 min with rapid staining kits) imaged by the EpiView-D4 were adequate for assessment of lesional cellularity and tumor content. We also found our device could reliably distinguish between HER2 expression levels across multiple different cell lines and animal xenografts. In a pilot study with human tissue (n = 19), we were able to accurately categorize HER2-negative and HER2-positve tumors from FNA specimens. Taken together, the EpiView-D4 offers a promising alternative to invasive-and often unavailable-pathology services and may enable the democratization of effective breast cancer management in limited-resource settings.

Multiplexed, quantitative serological profiling of COVID-19 from blood by a point-of-care test.

Highly sensitive, specific, and point-of-care (POC) serological assays are an essential tool to manage coronavirus disease 2019 (COVID-19). Here, we report on a microfluidic POC test that can profile the antibody response against multiple severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens-spike S1 (S1), nucleocapsid (N), and the receptor binding domain (RBD)-simultaneously from 60 µl of blood, plasma, or serum. We assessed the levels of antibodies in plasma samples from 31 individuals (with longitudinal sampling) with severe COVID-19, 41 healthy individuals, and 18 individuals with seasonal coronavirus infections. This POC assay achieved high sensitivity and specificity, tracked seroconversion, and showed good concordance with a live virus microneutralization assay. We can also detect a prognostic biomarker of severity, IP-10 (interferon-γ-induced protein 10), on the same chip. Because our test requires minimal user intervention and is read by a handheld detector, it can be globally deployed to combat COVID-19.

Postoperative Pain Relief after Pancreatic Resection: Systematic Review and Meta-Analysis of Analgesic Modalities.

BACKGROUND: This systematic review explored the efficacy of different pain relief modalities used in the management of postoperative pain following pancreatoduodenectomy (PD) and distal pancreatectomy (DP) and impact on perioperative outcomes. METHODS: MEDLINE (OVID), Embase, Pubmed, Web of Science and CENTRAL databases were searched using PRISMA framework. Primary outcomes included pain on postoperative day 2 and 4 and respiratory morbidity. Secondary outcomes included operation time, bile leak, delayed gastric emptying, postoperative pancreatic fistula, length of stay, and opioid use. RESULTS: Five randomized controlled trials and seven retrospective cohort studies (1313 patients) were included in the systematic review. Studies compared epidural analgesia (EDA) (n = 845), patient controlled analgesia (PCA) (n = 425) and transabdominal wound catheters (TAWC) (n = 43). EDA versus PCA following PD was compared in eight studies (1004 patients) in the quantitative meta-analysis. Pain scores on day 2 (p = 0.19) and 4 (p = 0.18) and respiratory morbidity (p = 0.42) were comparable between EDA and PCA. Operative times, bile leak, delayed gastric emptying, pancreatic fistula, opioid use, and length of stay also were comparable between EDA and PCA. Pain scores and perioperative outcomes were comparable between EDA and PCA following DP and EDA and TAWC following PD. CONCLUSIONS: EDA, PCA and TAWC are the most frequently used analgesic modalities in pancreatic surgery. Pain relief and other perioperative outcomes are comparable between them. Further larger randomized controlled trials are warranted to explore the relative merits of each analgesic modality on postoperative outcomes with emphasis on postoperative complications.

Ultrasensitive point-of-care immunoassay for secreted glycoprotein detects Ebola infection earlier than PCR.

Ebola virus (EBOV) hemorrhagic fever outbreaks have been challenging to deter due to the lack of health care infrastructure in disease-endemic countries and a corresponding inability to diagnose and contain the disease at an early stage. EBOV vaccines and therapies have improved disease outcomes, but the advent of an affordable, easily accessed, mass-produced rapid diagnostic test (RDT) that matches the performance of more resource-intensive polymerase chain reaction (PCR) assays would be invaluable in containing future outbreaks. Here, we developed and demonstrated the performance of a new ultrasensitive point-of-care immunoassay, the EBOV D4 assay, which targets the secreted glycoprotein of EBOV. The EBOV D4 assay is 1000-fold more sensitive than the U.S. Food and Drug Administration-approved RDTs and detected EBOV infection earlier than PCR in a standard nonhuman primate model. The EBOV D4 assay is suitable for low-resource settings and may facilitate earlier detection, containment, and treatment during outbreaks of the disease.

Operative experience in essential emergency general surgery procedures: is autonomy achievable during surgical training?

BACKGROUND: Readiness for practice is an ongoing concern in surgery. Surgeons who have completed general surgery training are expected to be proficient in performing common emergency procedures. The aim of this study was to assess the experience and autonomy of general surgery trainees in New Zealand in 10 emergency general surgery procedures, and identify factors associated with reaching primary operator (PO) thresholds. METHODS: Operative logbook data from all New Zealand general surgery trainees from 2013 to 2017 were analysed. Data for 10 emergency general surgery procedures were extracted to determine PO and autonomous PO (mentor not scrubbed) rates. A threshold of 70% for PO and APO rates was used to define two levels of proficiency. RESULTS: A total of 120 trainees performed 40 865 included procedures. Trainees met the PO threshold for all procedures by Surgical Education and Training (SET) 5. The APO threshold was met for three of 10 procedures (appendicectomy, drainage of perianal abscess and perforated peptic ulcer repair). Final APO rates for the other procedures ranged from 18% to 58%. On multivariate analysis, SET year and case volume were associated with increased odds of meeting the PO and APO thresholds. Female trainees were less likely to reach the PO and APO thresholds for three of 10 and four of 10 procedures, respectively. CONCLUSION: Trainees had increasing PO and autonomous PO rates over the course of their training. Graduating New Zealand general surgeons likely have sufficient operative experience in emergency general surgery procedures. However, rates of autonomy are lower, and further research is needed to determine whether this affects readiness for independent practice.

Hepato-pancreato-biliary and transplant surgery experience among New Zealand general surgery trainees.

BACKGROUND: Subspecialty surgery experience during general surgery training in Australasia is influenced by many factors, including duration of training, training location and the introduction of post-fellowship training programmes. Experience in hepato-pancreato-biliary (HPB) and transplant surgery is part of the general surgery curriculum, although trainee experience in these subspecialties has not been quantified in this region, which is relevant to post-fellowship training programmes. Therefore, the aim of this study was to quantify the HPB and transplant operative experience of New Zealand (NZ) general surgery trainees. METHODS: Operative logbook data were analysed for all NZ trainees from 2013 to 2017, including procedures categorized as pancreatic, biliary, hepatic and transplant surgery only. The number of cases within each category was used to model the cumulative operative experience over a 5-year training programme. RESULTS: During the study period, 118 trainees (303 trainee years) recorded 15 662 HPB and transplant procedures. Of these, 13 838 (88.4%) were cholecystectomies (mean cumulative experience 219.3 cases). Excluding cholecystectomy, trainees had a mean cumulative experience of 5.7 biliary, 7.5 pancreatic, 8.1 liver and 4.2 transplant procedures during their training. Transplant experience was predominantly access for peritoneal dialysis (228/260, 86.7%), with cumulative transplant experience otherwise reaching 0.47 procedures over 5 years. CONCLUSION: Exposure to HPB and transplant surgery during general surgery training in NZ is limited beyond cholecystectomy. Additional exposure during post-fellowship training is likely required for general surgeons to practice in these subspecialties.

An infrequently encountered case of spontaneous subcapsular liver hematoma with hepatic artery pseudoaneurysm.

Hepatic artery pseudoaneurysm (HAP) is a rare complication of liver trauma and liver transplant, and spontaneous subcapsular liver hematoma is not frequently encountered outside the setting of preeclampsia and hemolysis, elevated liver enzyme and low platelet (HELLP) syndrome. We report a rare case of spontaneous subcapsular liver hematoma with hepatic artery pseudoaneurysm without any apparent liver trauma or recent interventional procedures of the hepatobiliary system. Although subcapsular hepatic hematoma and HAP are uncommon diagnoses, clinicians should be aware of these diagnoses to promptly diagnose and effectively treat them. Clinicians should also not forget these diseases could be masked by other common etiologies, such as gastritis.

Fully printed prothrombin time sensor for point-of-care testing.

With an increasing number of patients relying on blood thinners to treat medical conditions, there is a rising need for rapid, low-cost, portable testing of blood coagulation time or prothrombin time (PT). Current methods for measuring PT require regular visits to outpatient clinics, which is cumbersome and time-consuming, decreasing patient quality of life. In this work, we developed a handheld point-of-care test (POCT) to measure PT using electrical transduction. Low-cost PT sensors were fully printed using an aerosol jet printer and conductive inks of Ag nanoparticles, Ag nanowires, and carbon nanotubes. Using benchtop control electronics to test this impedance-based biosensor, it was found that the capacitive nature of blood obscures the clotting response at frequencies below 10 kHz, leading to an optimized operating frequency of 15 kHz. When printed on polyimide, the PT sensor exhibited no variation in the measured clotting time, even when flexed to a 35 mm bend radius. In addition, consistent PT measurements for both chicken and human blood illustrate the versatility of these printed biosensors under disparate operating conditions, where chicken blood clots within 30 min and anticoagulated human blood clots within 20-100 s. Finally, a low-cost, handheld POCT was developed to measure PT for human blood, yielding 70% lower noise compared to measurement with a commercial potentiostat. This POCT with printed PT sensors has the potential to dramatically improve the quality of life for patients on blood thinners and, in the long term, could be incorporated into a fully flexible and wearable sensing platform.

Multiplexed, quantitative serological profiling of COVID-19 from a drop of blood by a point-of-care test.

Highly sensitive, specific, and point-of-care (POC) serological assays are an essential tool to manage the COVID-19 pandemic. Here, we report on a microfluidic, multiplexed POC test that can profile the antibody response against multiple SARS-CoV-2 antigens - Spike S1 (S1), Nucleocapsid (N), and the receptor binding domain (RBD) - simultaneously from a 60 microliter drop of blood, plasma, or serum. We assessed the levels of anti-SARS-CoV-2 antibodies in plasma samples from 19 individuals (at multiple time points) with COVID-19 that required admission to the intensive care unit and from 10 healthy individuals. This POC assay shows good concordance with a live virus microneutralization assay, achieved high sensitivity (100%) and specificity (100%), and successfully tracked the longitudinal evolution of the antibody response in infected individuals. We also demonstrated that we can detect a chemokine, IP-10, on the same chip, which may provide prognostic insight into patient outcomes. Because our test requires minimal user intervention and is read by a handheld detector, it can be globally deployed in the fight against COVID-19 by democratizing access to laboratory quality tests.

Assessment of Autonomy in Operative Procedures Among Female and Male New Zealand General Surgery Trainees.

Importance: The need for trainee sex equality within surgical training has resulted in an appraisal of the training experience in the New Zealand general surgery training program. Objective: To investigate the association between trainee sex and surgical autonomy in the operating room in the New Zealand general surgery training program. Design, Setting, and Participants: Retrospective cohort study conducted from December 10, 2012, to December 10, 2017, examining all endoscopic, major, and minor procedures performed by all New Zealand general surgery trainees in every training hospital in New Zealand. Main Outcomes and Measures: The primary outcome was the level of meaningful autonomy by each New Zealand general surgery trainee (ie, trainee as primary operator without the surgeon mentor scrubbed for the case). Outcomes were compared using multivariable analysis. Results: This study included 120 New Zealand general surgery trainees (42 women [35%] and 78 men [65%]) who were analyzed over 279.5 trainee-years (88.5 trainee-years for women and 191.0 trainee-years for men). Included were 119 380 general surgery procedures (17 465 endoscopic, 56 964 major, and 44 951 minor) in 18 hospitals. By the end of the 5-year training program, female trainees had a lower cumulative mean autonomous caseload than male trainees for endoscopic (284.0 [95% CI, 207.0-361.0] vs 352.2 [95% CI, 282.9-421.6], P = .03), major (139.9 [95% CI, 76.7-203.2] vs 198.1 [95% CI, 142.3-254.0], P = .02), and minor (456.3 [95% CI, 394.8-517.9] vs 519.9 [95% CI, 465.6-574.2], P = .007) procedures. Conclusions and Relevance: After accounting for differences among trainees, hospital type, number of female and male surgeon mentors at each hospital, and trainee seniority, female trainees performed fewer cases with meaningful autonomy compared with male trainees. These findings support the need for pragmatic solutions to address this bias and further investigations on mechanisms contributing to discrepancies.

In Pursuit of Zero 2.0: Recent Developments in Nonfouling Polymer Brushes for Immunoassays.

"Nonfouling" polymer brush surfaces can greatly improve the performance of in vitro diagnostic (IVD) assays due to the reduction of nonspecific protein adsorption and consequent improvement of signal-to-noise ratios. The development of synthetic polymer brush architectures that suppress adventitious protein adsorption is reviewed, and their integration into surface plasmon resonance and fluorescent sandwich immunoassay formats is discussed. Also, highlighted is a novel, self-contained immunoassay platform (the D4 assay) that transforms time-consuming laboratory-based assays into a user-friendly and point-of-care format with a sensitivity and specificity comparable or better than standard enzyme-linked immunosorbent assay (ELISA) directly from unprocessed samples. These advancements clearly demonstrate the utility of nonfouling polymer brushes as a substrate for ultrasensitive and robust diagnostic assays that may be suitable for clinical testing, in field and laboratory settings.

Aerosol jet printing of biological inks by ultrasonic delivery.

Printing is a promising method to reduce the cost of fabricating biomedical devices. While there have been significant advancements in direct-write printing techniques, non-contact printing of biological reagents has been almost exclusively limited to inkjet printing. Motivated by this lacuna, this work investigated aerosol jet printing (AJP) of biological reagents onto a nonfouling polymer brush to fabricate in vitro diagnostic (IVD) assays. The ultrasonication ink delivery process, which had previously been reported to damage DNA molecules, caused no degradation of printed proteins, allowing printing of a streptavidin-biotin binding assay with sub-nanogram ml-1 analytical sensitivity. Furthermore, a carcinoembryogenic antigen IVD was printed and found to have sensitivities in the clinically relevant range (limit of detection of approximately 0.5 ng ml-1 and a dynamic range of approximately three orders of magnitude). Finally, the multi-material printing capabilities of the aerosol jet printer were demonstrated by printing silver nanowires and streptavidin as interconnected patterns in the same print job without removal of the substrate from the printer, which will facilitate the fabrication of mixed-material devices. As cost, versatility, and ink usage become more prominent factors in the development of IVDs, this work has shown that AJP should become a more widely considered technique for fabrication.

Architectural Modification of Conformal PEG-Bottlebrush Coatings Minimizes Anti-PEG Antigenicity While Preserving Stealth Properties.

Poly(ethylene glycol) (PEG), a linear polymer known for its "stealth" properties, is commonly used to passivate the surface of biomedical implants and devices, and it is conjugated to biologic drugs to improve their pharmacokinetics. However, its antigenicity is a growing concern. Here, the antigenicity of PEG is investigated when assembled in a poly(oligoethylene glycol) methacrylate (POEGMA) "bottlebrush" configuration on a planar surface. Using ethylene glycol (EG) repeat lengths of the POEGMA sidechains as a tunable parameter for optimization, POEGMA brushes with sidechain lengths of two and three EG repeats are identified as the optimal polymer architecture to minimize binding of anti-PEG antibodies (APAs), while retaining resistance to nonspecific binding by bovine serum albumin and cultured cells. Binding of backbone- versus endgroup-selective APAs to POEGMA brushes is further investigated, and finally the antigenicity of POEGMA coatings is assessed against APA-positive clinical plasma samples. These results are applied toward fabricating immunoassays on POEGMA surfaces with minimal reactivity toward APAs while retaining a low limit-of-detection for the analyte. Taken together, these results offer useful design concepts to reduce the antigenicity of polymer brush-based surface coatings used in applications involving human or animal matrices.