Point-of-care Research Articles

A portable surface plasmon resonance (SPR) sensor for the detection of immunoglobulin A in plasma.

A life-threatening anaphylactic shock can occur if a patient with undiagnosed immunoglobulin A (IgA) deficiency (i.e., IgA levels <500 ng/mL) receives IgA-containing blood, hence the need for a rapid, point-of-care (POC) method for IgA deficiency screening. Enzyme-linked immunosorbent assay (ELISA) is routinely used to detect IgA, but this method requires trained specialists and ≥24 h to obtain a result. We developed a surface plasmon resonance (SPR)-based protocol to identify IgA-deficient patients or donors within 1 h. The SPR sensor relies on the detection of IgAs captured by primary antibodies adsorbed on the SPR chip and quantified with secondary antibodies. The sensor was calibrated from 0 to 2000 ng/mL in buffer, IgA-depleted human serum, and plasma samples from IgA-deficient individuals. A critical concentration of 500 ng/mL was set for IgA deficiency. The optimized sensor was then tested on eight plasma samples with known IgA status (determined by ELISA), including five with IgA deficiency and three with normal IgA levels. The limit of detection was estimated at 30 ng/mL in buffer and 400 ng/mL in diluted plasma. The results obtained fully agreed with ELISA among the eight plasma samples tested. The protocol distinguished IgA-deficient from normal samples, even for samples with an IgA concentration closer to critical concentration. In conclusion, we developed a reliable POC assay for the quantification of IgA in plasma. This test may permit POC testing at blood drives and centralized centers to maintain reserves of IgA-deficient blood and in-hospital testing of blood recipients.

Highly integrable silicon micropumps using lateral electrostatic bending actuators

We present the design, fabrication, and characterization of an innovative silicon-based micropump with high potential for portable lab-on-chip (LoC) as well as point-of-care (PoC) applications. The actuators of the pump are electrostatic driven in-plane bending devices, which were presented earlier (Borcia et al. in Phys Rev Fluids 3(8): 084202, 2018. 10.1103/PhysRevFluids.3.084202; Uhlig et al. in Micromachines, 9(4), 2018. 10.3390/mi9040190). This paper presents the characterization results achieved with the micropump. The dielectric non-polar liquid Novec7100™ was used as a test liquid due to its adequate physical properties. When applying a periodic voltage of 130 V, a flow rate of up to 80 µL/min was detected. The counter pressure amounts up to 30 kPa and the correspondent fluidic power (volumetric flow rate times the counter pressure) was calculated to 10 µW. The pump contains passive flap valves at the inlet and outlet, which are based on a bending cantilever design. Depending on the application requirements, the micropump can be designed modularly to adjust the specific parameters by an adequate arrangement of pump base units. In this paper, the proof of principle is shown using a single base unit with different number of stacked NED-actuator beams, as well as the serial arrangement of base units. Both modular concepts target the increase of backpressure of the NED-micropump in an inherently different way compared to conventional membrane micropumps.

RNA-Based Sensor Systems for Affordable Diagnostics in the Age of Pandemics.

In the era of the COVID-19 pandemic, the significance of point-of-care (POC) diagnostic tools has become increasingly vital, driven by the need for quick and precise virus identification. RNA-based sensors, particularly toehold sensors, have emerged as promising candidates for POC detection systems due to their selectivity and sensitivity. Toehold sensors operate by employing an RNA switch that changes the conformation when it binds to a target RNA molecule, resulting in a detectable signal. This review focuses on the development and deployment of RNA-based sensors for POC viral RNA detection with a particular emphasis on toehold sensors. The benefits and limits of toehold sensors are explored, and obstacles and future directions for improving their performance within POC detection systems are presented. The use of RNA-based sensors as a technology for rapid and sensitive detection of viral RNA holds great potential for effectively managing (dealing/coping) with present and future pandemics in resource-constrained settings.

SERS biosensor with plastic antibodies for detection of a cancer biomarker protein

Surface-enhanced Raman scattering (SERS) is a powerful method for detecting breast cancer-specific biomarkers due to its extraordinary enhancement effects obtained by localized surface plasmon resonance (LSPR) in metallic nanostructures at hotspots. In this research, gold nanostars (AuNSs) were used as SERS probes to detect a cancer biomarker at very low concentrations. To this end, we combined molecularly imprinted polymers (MIPs) as a detection layer with SERS for the detection of the biomarker CA 15–3 in point-of-care (PoC) analysis. This required two main steps: (i) the deposition of MIPs on a gold electrode, followed by a second step (ii) antibody binding with AuNSs containing a suitable Raman reporter to enhance Raman signaling (SERS). The MPan sensor was prepared by electropolymerization of the monomer aniline in the presence of CA 15–3. The template molecule was then extracted from the polymer using sodium dodecyl sulfate (SDS). In parallel, a control material was prepared in the absence of the protein (NPan). Surface modification for the control was performed using electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The performance of the sensor was evaluated using the SERS technique, in which the MPan sensor is first incubated with the protein and then exposed to the SERS probe. Under optimized conditions, the device showed a linear response to CA 15–3 concentrations from 0.016 to 248.51 U mL−1 in a PBS buffer at pH 7.4 in 1000-fold diluted serum. Overall, this approach demonstrates the potential of SERS as an optical reader and opens a new avenue for biosensing applications.Graphical

An early and trustable indicator suggestive of non-tuberculosis mycobacteria isolation in a high tuberculosis burden setting

Distinguishing between nontuberculous mycobacterial (NTM) lung infections and pulmonary tuberculosis becomes challenging due to their similar clinical manifestations and radiological images. Consequently, instances of delayed diagnosis or misdiagnosis are highly frequent. A feasible and reliable indicator of the existence of NTM in the early stages of the disease would help to solve this dilemma. In this study, we evaluated the potential of smear-positive and Xpert assay (Cepheid, USA) negative outcomes as an early indicator of possible NTM infection in a high TB-burden setting retrospectively and prospectively. During the study period, 12·77% (138/1081) of the smear-positive cases yielded negative outcomes with the simultaneous Xpert assay. From the 110 patients who yielded smear-positive/Xpert-negative outcomes and cultivated strain as well, 105 (95·45%) were proved to have NTM isolated. By incorporating an additional criterion of a negative result from the Interferon-gamma release assay, the accuracy of the screening method reached 100%. Regarding the NTM presence prediction value, smear-positive/Xpert-negative has a sensitivity of 24·86% (45/181) in all NTM isolated cases but 93·75-96·55% accuracy in retrospective study or 93·75% accuracy in prospective study in smear-positive NTM isolated cases. In addition, the specificity was ∼99·47% (943/948) in smear-positive tuberculosis cases. The clue of the presence of NTM could be obtained on the first day of the hospital visit due to the point of care (POC) feature of smear testing and Xpert assay. About one-fourth of the NTM-isolated patients would benefit from this rapid, convenient, and reliable screening strategy in the given circumstance. Smear-positive/Xpert-negative outcome is an early, trustable indicator that is indicative of NTM isolation.

Assessment of the effect of long-term serum storage for retrospective serologic diagnosis of canine monocytic ehrlichiosis (Ehrlichia canis)

There is currently sparse information on the possible effect of long-term storage of serum specimens for the retrospective serodiagnosis of canine monocytic ehrlichiosis (CME). The aim of this study was to assess the agreement between the original serologic outcome and the results of a repeat indirect fluorescent antibody (IFA) assay for the detection of IgG antibodies against E. canis. A secondary aim was to compare the diagnostic performance of two commercially available point-of-care (POC) immunochromatographic (IC) assays. Archived serum samples originally tested as positive (n=66) or negative (n=19) for E. canis IgG antibodies and kept frozen at −20°C for a median of 22 years, were retrospectively examined by IFA and by two POC IC assays. Cohen’s Kappa coefficient (0.748, p < 0.0001), indicated a substantial agreement between the original and repeat serologic testing results. An almost identical high sensitivity and moderate specificity were established for the two POC IC assays. Canine serum specimens on long-term storage may still be of value for seroepidemiologic surveys investigating the exposure to E. canis.

African Swine Fever Diagnosis in Africa: Challenges and Opportunities.

The global spread of African swine fever (ASF) in recent decades has led to the need for technological advances in sampling and diagnostic techniques. The impetus for these has been the need to enable sampling by lay persons and to obtain at least a preliminary diagnosis in the field for early control measures to be put in place before final laboratory confirmation. In rural Africa, rapid diagnosis is hampered by challenges that include lack of infrastructure as well as human and financial resources. Lack of animal health personnel, access to affordable means to transport field samples to a laboratory, and lack of laboratories with the capacity to make the diagnosis result in severe under-reporting of ASF, especially in endemic areas. This review summarizes the challenges identified in gap analyses relevant to low- and middle-income countries, with a focus on Africa, and explore the opportunities provided by recent research to improve field diagnosis and quality of diagnostic samples used. Sampling techniques include invasive sampling techniques requiring trained personnel and non-invasive sampling requiring minimal training, sampling of decomposed carcass material, and preservation of samples in situations where cold chain maintenance cannot be guaranteed. Availability and efficacy of point-of-care (POC) tests for ASF has improved considerably in recent years and their application, as well as advantages and limitations, are discussed. The adequacy of existing laboratory diagnostic capacity is evaluated and opportunities for networking amongst reference and other laboratories offering diagnostic services are discussed. Maintaining laboratory diagnostic efficiency in the absence of samples during periods of quiescence is another issue that requires attention, and the role of improved laboratory networking is emphasized. Early diagnosis of ASF is key to managing the disease spread. Therefore, the establishment of the Africa Chapter of the Global African Swine Fever Research Alliance (GARA) increases opportunities for collaboration and networking among the veterinary diagnostic laboratories in the region.

Miniaturized MXene-based electrochemical biosensors for virus detection

The timely control of infectious diseases can prevent the spread of infections and mitigate the significant socio-economic damage witnessed during recent pandemics. Diagnostic methods play a significant role in detecting highly contagious agents, such as viruses, to prevent further transmission. The emergence of advanced point-of-care techniques offers several advantages over conventional approaches for detecting infectious agents. These techniques are highly sensitive, rapid, can be miniaturized, and are cost-effective. Recently, MXene-based 2D nanocomposites have proven beneficial for fabricating electrochemical biosensors due to their suitable electrical, optical, and mechanical properties. This article covers electrochemical biosensors based on MXene nanocomposite for the detection of viruses, along with the associated challenges and future possibilities. Additionally, we highlight various conventional techniques for the detection of infectious agents, discussing their pros and cons. We delve into the challenges faced during the fabrication of MXene-based biosensors and explore future endeavors. It is anticipated that the information presented in this work will pave the way for the development of Point-of-Care (POC) devices capable of sensitive and selective virus detection, enhancing preparedness for ongoing and future pandemics.

Accuracy of point-of-care capillary blood sugar measurements in critically ill patients: An observational study.

Accurately monitoring blood glucose levels is vital for critically ill individuals. Point-of-care (POC) glucose meters are commonly used in local intensive care units (ICUs). This study aimed to assess the precision of POC glucose meter readings in critically ill individuals with specific evaluation in patients with and without shock against the reference standard of venous blood glucose measurements. An observational study was done on adult patients admitted in the ICU at a teaching institution. Capillary blood samples were collected from the patient's fingertip using lancet device with aseptic measures. The sample was analyzed using the GlucoCare Sense Glucometer (RMD Mediaids Limited, Taiwan). At the same time, 2 ml of blood was drawn from the patient's peripheral veins and analyzed by glucose oxidase-peroxidase method as reference. POC glucose measurements averaged 140 ± 20.23 mg/dl, while laboratory values were recorded as 116.10 ± 17.13 mg/dl. The difference between the two methods was 24.34 ± 12.01 mg/dl. A strong correlation (r = 0.805) was found between capillary and laboratory blood glucose levels, indicating a significant association (P < 0.0001). Twenty-two (44%) patients were in shock during the study. The mean difference between laboratory and POC blood glucose levels was higher in patients with circulatory shock (36.82 ± 4.84 mg/dl) than those without shock (14.61 ± 4.49 mg/dl), P < 0.05. POC glucose meters may lead to underdetection of hypoglycemia in critically ill patients, as their values are higher than laboratory values. Moreover, the results showed that POC glucometers are inaccurate for monitoring glucose in hypotensive patients in shock. Standard venous glucose monitoring methods may be more appropriate for these patients.

Optimising HIV drug resistance testing laboratory networks in Kenya: insights from systems engineering modelling

BackgroundHIV drug resistance (DR) is a growing threat to the durability of current and future HIV treatment success. DR testing (DRT) technologies are very expensive and specialised, relying on centralised...

Effectiveness of AI-driven Individualized Learning Approach for Children with Autism Spectrum Disorder (ASD)

IntroductionAutism Spectrum Disorder (ASD) is a condition with varying degrees of social, emotional and behavioural disability. These children require focused and individualised learning plan to facilitate social integration. Robots have been used for this purpose but are not routinely available in several parts of the world. Effective, point of care (POC) digital therapies that can be used anywhere by anyone is the need of the day.ObjectivesTo evaluate the effectiveness of Artificial Intelligence (AI) driven individualised learning plans delivered through POC digital platform (CognitiveBotics) for children with ASD.MethodsAfter Ethical approval and parental consent, children diagnosed with ASD (Childhood Autism Rating Scale CARS 2) aged 2 years and above were screened for study inclusion and exclusion criteria and enrolled. AI driven individualised learning plan was administered through CognitiveBotics software that could be used on either computer or a tablet. Initially, interactive questions were administered to parents by the AI tool to understand child’s functioning. Based on these, an individualised learning plan was assigned. Each task is delivered using either interactive videos, chatbot and/or animated/AI games. The child’s progress is captured for attention (attempted questions, retries and timeouts) and retention (first time corrects and corrects) continuously. The initial interactive questions administered to parents were repeated to assess child’s progress in real life. Paired ‘t’ test using SPSS version 26 was used to compare initial and final data.ResultsOut of 85 registered children, 41 regularly used the AI tool. Mean age was 43.93 months (range 26 to 72 months). 37 (90.24%) were boys. The baseline mean scores (ranges), were CARS 33.48 (30-39.5); Social quotient 53.4 (27.25-80.32), Developmental quotient 71.35 (45.90-93.33) and IQ 62.34 (36.58-86.83). The base line mean score of parents assessed child function was 115.24 (range 58 to 215). A mean of 15.54 tasks were given (range 5 to 48). At the time of analysis with a mean follow up of 3 months (range 2 to 5 months) the children completed a mean of 10.10 tasks (range 0 to 42). There was significant improvement in child’s learning captured by the AI software based on attention and retention parameters (p = &lt;0.00001). This improvement was also reflected in parent assessed child function (mean 147.15, (59 to 231)) (p = &lt;0.00001). The percentage of improvement in both software captured and parent assessed child function was directly related to the amount of time spent by the child on the software.ConclusionsAI driven individualised learning approach is effective in teaching skills and promote social integration for children with ASD. Such technology can capture the child’s progress on a day-to-day basis and deliver personalised training.Disclosure of InterestNone Declared

Overview on utility of in-house tests for detection of systemic infectious diseases in dogs

For detection of infectious diseases, several point-of-care (POC) tests are on the market in addition to methods performed in commercial laboratories. These POC tests are based on enzyme-linked immunosorbent assay (ELISA) or other immunochromatographic technologies and present results within few minutes in veterinary practice. This article gives an overview of the utility of numerous POC tests of different manufacturers for detection of parvovirus antigen in feces, Dirofilaria (D.) immitis antigen in blood as well as antibodies against Borrelia (B.) burgdorferi, Anaplasma (A.) spp., Ehrlichia (E.) spp., Leptospira (L.) spp. and Leishmania (L.) infantum in blood (single or in different combinations). Sensitivity and specificity of these tests are important for their usefulness in veterinary practice. Furthermore, presence of antibodies or detection of antigen has to correlate with the presence of clinical signs. POC tests for detection of canine parvovirus antigen have a very high specificity, the sensitivity of all evaluated POC tests, however, is very low. POC tests for detection of D. immitis antigen have a very high sensitivity and specificity. As they detect antigen from the uterus of female adult parasites, test results are negative when only very few female or only male adults are present. POC tests for detection of antibodies against B. burgdorferi only indicate contact with Borrelia spp. and do not prove clinical Lyme disease, as the infection only extremely rarely causes clinical signs. POC tests for detection of antibodies against A. phagocytophilum are also not suitable for diagnosis of clinical anaplasmosis. Infections with A. phagocytophilum only lead to clinical disease in very rare cases and in these, clinical signs occur before the development of antibodies. POC tests for detection of antibodies against E. canis have a very high sensitivity as well as specificity. POC tests for detection of antibodies against L. infantum and Leptospira species (spp.) show a very high specificity and a high sensitivity. However, Leptospira spp. antibody-positive results may occur following vaccination, as the POC tests cannot distinguish between field and vaccination strains.

Hermetic microfluidic device for point-of-care viral nucleic acid testing

There is an unmet clinical and public health need for rapid and accurate point-of-care (POC) diagnosis and management of infectious pathogens, especially in resource-limited environments. In this work, we present a microfluidic deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) rapid test (μDART) device for POC detection of various viral pathogens. This platform hermetically integrates the modules of extraction-free sample lysis, loop-mediated isothermal amplification (LAMP) with lyophilized reagent beads, and real-time colorimetric signal sensing to realize "sample-in and result-out" in 15–30 min. Test results can be sent to a mobile phone for remote monitoring. Automated high-precision liquid handling is achieved by a combination of negative-pressure-driven microchambers and self-sealing valves, thus simplifying manual operations and eliminating the leakage of nucleic acid aerosols. The limit of detection (LOD) of the device is as low as ∼53 copies/mL or ∼2 copies/reaction for SARS-CoV-2, which is as sensitive as the gold standard of nucleic acid testing. To validate our device’s clinical applications, we tested both DNA and RNA viruses as representative pathogens including 537 clinical nasal swab samples for SARS-CoV-2, 74 cervical swab samples for human papillomavirus 16/18 (HPV16/18) and 82 pet swab samples for feline cupripoxvirus (FCV) and feline herpesvirus (FHV). Across these tests, the clinical sensitivity and specificity were 92.5% - 97.7% and 99.7%-100%, respectively. We demonstrate that the μDART is able to provide a quick and accurate result for POCT and self-testing, and can connect to health care wirelessly to achieve remote monitoring.

Retention in care of infants diagnosed with HIV at birth: Beyond the diagnostic strategy.

Birth HIV point-of-care (POC) tests curtail analytical testing issues and expedite diagnosis, potentially allowing for earlier mother-infant pair engagement and improved outcomes. Many children are lost post antiretroviral therapy (ART) initiation within the first 6 months of follow-up. We compared 6-month retention in care, HIV viral load (VL) suppression and mortality among infants diagnosed with HIV at birth, using laboratory-based versus POC HIV PCR testing. From 2018 to 2019, infants exposed to HIV underwent birth HIV PCR POC testing at Kalafong Provincial Tertiary Hospital in Tshwane District. Their outcomes were compared to a historical control born between 2014 and 2016, who exclusively underwent laboratory-based HIV PCR testing. Both groups received comparable HIV care following national guidelines. Fifty-seven infants were studied (POC: 27; Control: 30). The POC turnaround time was significantly shorter (POC: 15.5 h [IQR: 4.3-24.7], Control: 68.3 h [IQR 46.0-93.9]; p = < 0.0001). Both populations had the same elapsed time from HIV diagnosis to ART initiation (median: 13 days, POC: IQR 8-21 days; Control: IQR 9-36 days). Six infants were never initiated (POC: 2 [7%]; Control: 4 [13%]). At 6 months, overall care retention was 72% (41/57), higher among the Control group (Control 23/30, 77%; POC: 18/27, 67%). HIV viral suppression at 6 months was higher among the POC group (POC: 14/18, 78%; Control: 9/19, 47%, p = 0.09). No deaths were reported. Poor care retention at 6 months post ART initiation is concerning. Initial mother-infant visits should be effectively utilised to assess and manage potential risk factors for loss of follow-up. This study highlights the ongoing need to find workable solutions to improve retention in care, thereby ensuring the benefits of expedited HIV diagnosis and ART initiation.

Review: Impact of microfluidic cell and particle separation techniques on microplastic removal strategies

This review highlights the growing concern regarding the proliferation of microplastics (MPs) in aquatic ecosystems and their potential impact on both the environment and human health. Despite current efforts, a considerable number of MPs remain untreated due to their small size. Conventional identification and treatment methods are summarized pointing to the current limitations. Emerging technologies in microfluidics and nanotechnology are presented as potential solutions for the removal of MPs from aquatic environments. These novel technologies, which are currently being used for the development of novel point of care (PoC) diagnostic devices, can take advantage of the size and density similarities between MPs and commonly separated particles in microfluidics applications such as cells, making them promising candidates for MPs separation and recovery in wastewater treatment plants.This review evaluates the limitations of current MPs separation and recovery technologies in water treatment plants and laboratories and compares them with the promising capabilities of microfluidics and nanotechnology, providing valuable insights into future strategies for combating MPs pollution.

Point-of-Care HbA1c in Clinical Practice: Caveats and Considerations for Optimal Use.

Hemoglobin A1c (A1C) is widely used for the diagnosis and management of diabetes. Accurate measurement of A1C is necessary for optimal clinical value. Assay standardization has markedly improved the accuracy and consistency of A1C testing. Devices to measure A1C at point of care (POC) are commercially available, allowing rapid results when the patient is seen. In this review, we describe how standardization of A1C testing was achieved, leading to high-quality results in clinical laboratories. We address the use of POC A1C testing in clinical situations and summarize the advantages and disadvantages of POC A1C testing. We emphasize the importance of considering the limitations of these devices and following correct testing procedures to ensure that accurate A1C results are obtained for optimal care of patients.

PIS-Net: Efficient Medical Image Segmentation Network with Multivariate Downsampling for Point-of-Care.

Recently, with more portable diagnostic devices being moved to people anywhere, point-of-care (PoC) imaging has become more convenient and more popular than the traditional "bed imaging". Instant image segmentation, as an important technology of computer vision, is receiving more and more attention in PoC diagnosis. However, the image distortion caused by image preprocessing and the low resolution of medical images extracted by PoC devices are urgent problems that need to be solved. Moreover, more efficient feature representation is necessary in the design of instant image segmentation. In this paper, a new feature representation considering the relationships among local features with minimal parameters and a lower computational complexity is proposed. Since a feature window sliding along a diagonal can capture more pluralistic features, a Diagonal-Axial Multi-Layer Perceptron is designed to obtain the global correlation among local features for a more comprehensive feature representation. Additionally, a new multi-scale feature fusion is proposed to integrate nonlinear features with linear ones to obtain a more precise feature representation. Richer features are figured out. In order to improve the generalization of the models, a dynamic residual spatial pyramid pooling based on various receptive fields is constructed according to different sizes of images, which alleviates the influence of image distortion. The experimental results show that the proposed strategy has better performance on instant image segmentation. Notably, it yields an average improvement of 1.31% in Dice than existing strategies on the BUSI, ISIC2018 and MoNuSeg datasets.

A LAMP point-of-care test to guide antimicrobial choice for treatment of Staphylococcus pseudintermedius pyoderma in dogs

Staphylococcus pseudintermedius is the most common cause of pyoderma in dogs. We validated a point-of-care (PoC) test based on colorimetric loop-mediated isothermal amplification (LAMP) for rapid S. pseudintermedius identification and susceptibility testing for first line antimicrobials for systemic treatment of canine pyoderma, i.e., lincosamides, first generation cephalosporins and amoxicillin clavulanate. Newly designed LAMP primers targeting clinically relevant resistance genes were combined with a previously validated set of primers targeting spsL for species identification. After laboratory validation on 110 clinical isolates, we assessed the performance of the test on 101 clinical specimens using routine culture and susceptibility testing as a reference standard. The average hands-on and turnaround times for the PoC test were 30 and 90 min, respectively. The assay showed sensitivity and specificity near 100% for both species identification and susceptibility testing when performed on bacterial cultures or clinical specimens in the laboratory. However, the PoC test yielded less accurate results when performed on-site by clinical staff (92% sensitivity and 64% specificity for species identification, 67% sensitivity and 96% specificity for β-lactam susceptibility, and 83% sensitivity and 71% specificity for lincosamide susceptibility). These results indicate that the PoC test should be adapted to a user-friendly technology to facilitate performance and interpretation of results by clinical staff. If properly developed, the test would allow veterinarians to gain rapid information on antimicrobial choice, limiting the risk of treatment failure and facilitating adherence to antimicrobial use guidelines in small animal veterinary dermatology.

Boronate crosslinking-based ratiometric electrochemical assay of glycated albumin

As a product of nonenzymatic glycation, glycated albumin (GA) is a promising serum marker for the short-term glycemic monitoring in patients with diabetes. On the basis of the boronate crosslinking (BCL)-enabled direct labeling of ferrocene (Fc) tags to the nonenzymatically glycated (NEG) sites, we report herein a novel aptamer-based ratiometric electrochemical (apt-REC) platform for the point-of-care (POC) assay of GA. This apt-REC platform is based on the recognition of GA proteins by the methylene blue (MB)-modified aptamer receptors and the labeling of the Fc tags to the NEG sites via the BCL. Using MB as the reference tag and Fc as the quantification tag, the ratio of the oxidation currents (i.e., IFc/IMB) can serve as the yardstick for the ratiometric assay of GA. Due to the presence of tens of the NEG sites, each GA protein can be labeled with tens of quantification tags, permitting the amplified assay in a simple, time-saving, and low-cost manner. The ratiometric signal exhibited a good linear response over the range from 0.1 to 100 μg/mL, with a detection limit of 45.5 ng/mL. In addition to the superior reproducibility and robustness, this apt-REC platform is highly selective (capable of discriminating GA against human serum albumin (HSA)) and applicable to GA assay in serum samples. Due to its low cost, high reproducibility and robustness, simple operation, and high sensitivity and selectivity, this apt-REC platform holds great promise in the POC assay of GA for diabetes management.

Abstract 5027: Simplified selective electrochemical detection of ctDNA differentiates between cancer progression and regression

Abstract Advanced cancers therapies, including personalized ones, often fail. Rapid evaluation of treatment efficacy is therefore critical to reduce medical and financial side effects and, most importantly, facilitate the implementation of a therapy most appropriate for that individual. Current approaches for evaluating treatment are too slow and expensive to rapidly modify therapy. The previously documented selective affinity of DNA to Au surfaces, albeit cumbersome, unsuitable for point-of-care (PoC) applications and having poor discrimination ability, suggested a solution to this clinically important problem. Methods presented herein potentially solve the problem as first illustrated by a studies of plasma from those with and without cancers. Multiple improvements, most notably optimized buffer conditions dramatically changed and enhanced the difference in adsorption between ctDNA and normal cfDNA drastically improving assay performance. The enhanced sensitivity of this Therascape™ assay was not only able to better detect the difference between healthy and cancer cfDNA but demonstrated potential for the monitoring of cancer treatment efficacy. De-identified clinical samples of the few patients that the Scripps Biorepository and University of Colorado supplied had samples before and after treatment, and were known to have progressed or responded in the interim, were analyzed. This initial group included 6 lymphoma patients and two NSCLC patients (in one case the cfDNA was isolated from urine). One of the patient samples taken before initiating therapy was in the healthy range and considered ineligible for the assay. Ten before and after pairs were then evaluated in a blinded fashion. TheraScape correctly correlated with the change in cancer burden in each pair (10/10 times, p = 0.00016, paired t-test). In some cases the “after” specimen was ~1 month after therapy began. The presentation will include additional patients. The CVs of repeat electrodes were less than 10%, interoperator variability did not increase this. The novel method of detecting cfDNA using disposable electrodes presents a significant advancement in monitoring the efficacy of treatments for advanced cancers, and may be particularly critical for immunotherapy. This approach reduced expenses by 10 to 50 times compared to current reimbursement rates for sequence dependent methods, even more critical is the same day turn around would allow rapid, truly individualized, patient therapy optimization. Citation Format: Matthew Jordan Russo, Kirsten Arnold, Shannon Tunney, Suzin Wright, Floyd Taub, Charles S. Henry. Simplified selective electrochemical detection of ctDNA differentiates between cancer progression and regression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5027.