Point-of-care Research Articles

Aptamer-conjugated gold nanoparticles for portable, ultrasensitive naked-eye detection of C-reactive protein based on the Tyndall effect

BackgroundC-reactive protein (CRP) represents an early clinical biomarker that indicates the presence of inflammatory or infectious conditions in the human body. Today's procedures approved by the Food and Drug Administration (FDA) imply expensive equipment and highly trained personnel to perform the test. Therefore, a new diagnostic method with high detection efficiency and less cost is urgently needed for delivering rapid and timely results in point-of-care (POC) service. ResultsHerein, we propose a new, equipment-free, and portable sensing method for the future POC detection of CRP based on the Tyndall effect (TE). In our study, aptamer-conjugated citrate-stabilized gold nanoparticles (apta-AuNPs) are exploited as the sensing platform. The apta-AuNPs’ interaction with CRP in a saline environment leads to their aggregation, thus enhancing the scattering of light when the solution is exposed to a 640 nm pointer laser line. Firstly, the enhancement of the scattering light as a function of increasing concentration of CRP in solution is measured spectroscopically using a typical 90-degree angle spectrofluorometer and then the measurements are compared to the classic colorimetric detection using an UV–Vis spectrophotometer. Finally, to achieve high portability and accessibility, we demonstrate that the measurement of CRP concentration can be performed with similar accuracy but in a more direct and inexpensive way by using a laser pointer pen as the excitation source and a camera of a low-budget smartphone as a quantitative reader instead of most expensive spectrofluorometer. SignificanceThe portable TE-based assay exhibits a wide linear dynamic range (1–60 μg/mL) for the detection of CRP with a limit of detection (LOD) of 92 ng/mL The proposed method is capable to integrate both standard and high-sensitivity CRP analysis in a single procedure with increased sensitivity and prompt delivery of analysis results. Moreover, the sensing procedure is significantly faster than the FDA approved ones with a detection time of only 10 min. Finally, as a proof-of-concept, our findings demonstrate excellent recovery for CRP detection in spiked and diluted urine samples, highlighting the strong potential of this sensing method for POC applications.

A dual-channel electrochemical biosensor enables concurrent detection of pathogens and antibiotic resistance

Diarrheagenic E. coli infections, commonly treated with β-lactam antibiotics, contribute to antibiotic resistance - a pressing public health concern. Rapid monitoring of pathogen antibiotic resistance is vital to combat antimicrobial spread. Current bacterial diagnosis methods identify pathogens or determine antibiotic resistance separately, necessitating multiple assays. There is an urgent need for tools that simultaneously identify infectious agents and their antibiotic resistance at the point of care (POC). We developed an integrated electrochemical chip-based biosensor for detecting enteropathogenic E. coli (EPEC), a major neonatal diarrheal pathogen, using an antibody against a virulence marker, termed EspB, and the β-lactam resistance marker, β-lactamase. A dual-channel microfabricated chip, bio-functionalized with a specific EspB monoclonal antibody, and nitrocefin, a β -lactamase substrate was utilized. The chip facilitated electrochemical impedance spectroscopy (EIS)-based detection of EspB antigen and EspB-expressing bacteria. For β-lactam resistance profiling, a second channel enabled differential-pulse voltammetric (DPV) measurement of hydrolyzed nitrocefin. EIS-based detection of EspB antigen was calibrated (LOD: 4.3 ng/mL ±1 and LOQ: 13.0 ng/mL ±3) as well as DPV-based detection of the antibiotic resistance marker, β-lactamase (LOD: 3.6 ng/mL ±1.65 and LOQ: 10 ng/mL ±4). The integrated EIS and DPV biosensor was employed for the simultaneous detection of EspB-expressing and β-lactamase-producing bacteria. The combined readout from both channels allowed the distinction between antibiotic-resistant and -sensitive pathogenic bacteria. The integrated electrochemical biosensor successfully achieved simultaneous, rapid detection of double positive EspB- and β-lactamase-expressing bacteria. Such distinction enabled by a portable device within a short assay time and a simplified sample preparation, may be highly valuable in mitigating the spread of AMR. This new diagnostic tool holds promise for the development of POC devices in clinical diagnosis.

Miniature mass spectrometer-based point-of-care assay for quantification of metformin and sitagliptin in human blood and urine.

Metformin (MET) and sitagliptin (STG) are widely used as the first-line and long-term oral hypoglycemic agents for managing type 2 diabetes mellitus (T2DM). However, the current lack of convenient and rapid measurement methods poses a challenge for individualized management. This study developed a point-of-care (POC) assay method utilizing a miniature mass spectrometer, enabling rapid and accurate quantification of MET and STG concentrations in human blood and urine. By combining the miniature mass spectrometer with paper spray ionization, this method simplifies the process into three to four steps, requires minimal amounts of bodily fluids (50 μL of blood and 2 μL of urine), and is able to obtain quantification results within approximately 2min. Stable isotope-labeled internal standards were employed to enhance the accuracy and stability of measurement. The MS/MS responses exhibited good linear relationship with concentration, with relative standard deviations (RSDs) below 25%. It has the potential to provide immediate treatment feedback and decision support for patients and healthcare professionals in clinical practice.

Patient-specific implants made of 3D printed bioresorbable polymers at the point-of-care: material, technology, and scope of surgical application

BackgroundBioresorbable patient-specific additive-manufactured bone grafts, meshes, and plates are emerging as a promising alternative that can overcome the challenges associated with conventional off-the-shelf implants. The fabrication of patient-specific implants (PSIs) directly at the point-of-care (POC), such as hospitals, clinics, and surgical centers, allows for more flexible, faster, and more efficient processes, reducing the need for outsourcing to external manufacturers. We want to emphasize the potential advantages of producing bioresorbable polymer implants for cranio-maxillofacial surgery at the POC by highlighting its surgical applications, benefits, and limitations.MethodsThis study describes the workflow of designing and fabricating degradable polymeric PSIs using three-dimensional (3D) printing technology. The cortical bone was segmented from the patient’s computed tomography data using Materialise Mimics software, and the PSIs were designed created using Geomagic Freeform and nTopology software. The implants were finally printed via Arburg Plastic Freeforming (APF) of medical-grade poly (L-lactide-co-D, L-lactide) with 30% β-tricalcium phosphate and evaluated for fit.Results3D printed implants using APF technology showed surfaces with highly uniform and well-connected droplets with minimal gap formation between the printed paths. For the plates and meshes, a wall thickness down to 0.8 mm could be achieved. In this study, we successfully printed plates for osteosynthesis, implants for orbital floor fractures, meshes for alveolar bone regeneration, and bone scaffolds with interconnected channels.ConclusionsThis study shows the feasibility of using 3D printing to create degradable polymeric PSIs seamlessly integrated into virtual surgical planning workflows. Implementing POC 3D printing of biodegradable PSI can potentially improve therapeutic outcomes, but regulatory compliance must be addressed.

Point-of-Care 3-Dimensional-Printed Polyetheretherketone Customized Implants for Cranioplastic Surgery of Large Skull Defects.

3-Dimensional (3D) printing has become a common tool to aid implant molding for cranioplastic surgery of large skull defects. Until now, 3D printing of cranial implants itself has not been used, mainly because of medicolegal concerns. With a 3D printer developed for printing medical applications and with implant-grade polyetheretherketone (PEEK) filament available, we established a workflow (in compliance with medical device regulations) to 3D print cranial implants for cranioplastic surgery directly at the point of care (POC). Here, we describe the implementation of 3D printing these PEEK implants for cranioplastic surgery at our academic hospital. A thorough design and 3D printing process, in accordance with local medical device regulations, was developed. Implants are digitally designed based upon pre- and post-craniectomy cranial computed tomography scans by trained 3D printing experts from the department of medical engineering at our institution. Implants are then produced on a medical 3D printer with implant-grade PEEK filament using the fused filament fabrication process. After postprocessing and steam sterilization, implantation for reconstruction of the skull can be performed. Cranioplastic surgery with a 3D-printed PEEK implant was performed at our institution in a patient with a large frontotemporoparietal skull defect after traumatic brain injury with consecutive decompressive craniectomy. No intra- or post-operative complications occurred. Postoperative cranial computed tomography scans showed perfect reconstruction of precraniectomy skull shape. The aesthetic result was promising and satisfactory to the patient. This novel 3D printing workflow enables the production of patient-specific cranial implants from PEEK, to reconstruct large skull defects directly at the POC in accordance with the European Medical Device Regulation. This marks an unprecedented technological and legal advancement, enabling the hospital infrastructure not only to deliver the cranioplastic surgery itself, but also additive manufacturing of the implant directly at the POC.

Recent Advances in Lateral Flow Assays for Viral Protein Detection with Nanomaterial-Based Optical Sensors.

Controlling the progression of contagious diseases is crucial for public health management, emphasizing the importance of early viral infection diagnosis. In response, lateral flow assays (LFAs) have been successfully utilized in point-of-care (POC) testing, emerging as a viable alternative to more traditional diagnostic methods. Recent advancements in virus detection have primarily leveraged methods such as reverse transcription-polymerase chain reaction (RT-PCR), reverse transcription-loop-mediated isothermal amplification (RT-LAMP), and the enzyme-linked immunosorbent assay (ELISA). Despite their proven effectiveness, these conventional techniques are often expensive, require specialized expertise, and consume a significant amount of time. In contrast, LFAs utilize nanomaterial-based optical sensing technologies, including colorimetric, fluorescence, and surface-enhanced Raman scattering (SERS), offering quick, straightforward analyses with minimal training and infrastructure requirements for detecting viral proteins in biological samples. This review describes the composition and mechanism of and recent advancements in LFAs for viral protein detection, categorizing them into colorimetric, fluorescent, and SERS-based techniques. Despite significant progress, developing a simple, stable, highly sensitive, and selective LFA system remains a formidable challenge. Nevertheless, an advanced LFA system promises not only to enhance clinical diagnostics but also to extend its utility to environmental monitoring and beyond, demonstrating its potential to revolutionize both healthcare and environmental safety.

Point-of-Care Diagnostic System for Viable Salmonella Species via Improved Propidium Monoazide and Recombinase Polymerase Amplification Based Nucleic Acid Lateral Flow.

Salmonella species are prominent foodborne microbial pathogens transmitted through contaminated food or water and pose a significant threat to human health. Accurate and rapid point-of-care (POC) diagnosis is gaining attention in effectively preventing outbreaks of foodborne disease. However, the presence of dead bacteria can interfere with an accurate diagnosis, necessitating the development of methods for the rapid, simple, and efficient detection of viable bacteria only. Herein, we used an improved propidium monoazide (PMAxx) to develop a nucleic acid lateral flow (NALF) assay based on recombinase polymerase amplification (RPA) to differentiate viable Salmonella Typhimurium. We selected an RPA primer set targeting the invA gene and designed a probe for NALF. RPA-based NALF was optimized for temperature (30-43 °C), time (1-25 min), and endonuclease IV concentration (0.025-0.15 unit/µL). PMAxx successfully eliminated false-positive results from dead S. Typhimurium, enabling the accurate detection of viable S. Typhimurium with a detection limit of 1.11 × 102 CFU/mL in pure culture. The developed method was evaluated with spiked raw chicken breast and milk with analysis completed within 25 min at 39 °C. This study has potential as a tool for the POC diagnostics of viable foodborne pathogens with high specificity, sensitivity, rapidity, and cost-effectiveness.

Nonenzymatic Detection of Glucose Using 3D Printed Carbon Electrodes in Human Saliva

One of the most prevalent diseases where point-of-care (POC) diagnostics has focused is diabetes, which impacts hundreds of millions of people globally. Due to the severe negative outcomes including renal failure, nerve damage, and stroke, many POC sensors have been designed to streamline low-cost testing. Recently, the utility of 3D printing for rapidly fabricating housings, electrodes, and sensors for use at the POC has been exploited toward diverse applications. Particularly interesting are 3D printed carbon electrodes (3DpCEs) in POC diagnostics owing to their simplicity, affordability, and mass production capabilities for developing sensors either for direct use or through post-printing surface modifications. Herein, we report a copper modified 3DpCE as a sensitive and selective nonenzymatic biosensor for glucose. Copper deposition, paired with an optimized activation protocol, produced a sensitive and selective sensor for glucose with a larger detection range, enhanced sensitivity, and better reproducibility compared to nonactivated and alkaline immersed 3DpCEs. The sensor displayed excellent linearity between 10–1800 μM and proved to be highly selective over common biologically relevant interferants. The 3D printed sensor successfully determined biologically relevant concentrations of glucose in human saliva which resulted in percent recoveries of 101 ± 8%, 106 ± 6%, and 98 ± 6% for 74, 402, and 652 μM glucose, respectively.

Combination of distance-based paper analytical devices with ionic liquid-based dispersive liquid-liquid microextraction for enzyme-free bilirubin quantification

This article introduces the first demonstration of integrating distance-based paper analytical devices (dPADs) with ionic liquid-based dispersive liquid-liquid microextraction (IL-DLLME) for the quantitative detection of bilirubin levels in human samples. In this approach, bilirubin is preconcentrated and extracted into a small droplet of the extraction solvent using IL-DLLME. The resulting solution is then introduced into an economical and straightforward dPAD sensor. Detection relies on a colorimetric reaction between bilirubin and gold ions (Au3+), leading to the in-situ formation of gold nanoparticles (AuNPs) on the paper substrate. The observed red-purple distance length is directly proportional to the bilirubin level. Under optimization, a linear range between 0.25 nM and 5.0 nM (R2 = 0.9979) and a detection limit (LOD) of 250.0 pM were achieved. The assay exhibits notable precision and selectivity without any interference. With its distance readout feature, this method is simpler and more cost-effective, offering greater sensitivity compared to other methods requiring expensive reagents and instruments. Moreover, the technique shows high accuracy and precision for bilirubin quantification in human control samples, with recoveries ranging from 98.33% to 102.00%. No significant difference was observed between our method and the enzyme-linked immunoassay (ELISA) method. By combining a low-cost microfluidic device with a simple microextraction method, this strategy holds great potential as an alternative analytical method for determining bilirubin. It can be expanded for further applications in analytical sensing for point-of-care (POC) diagnostics.

Smartphone-Based Point-of-Care Urinalysis Vivoo App: A Validation Study

Point-of-care (POC) analysis has emerged as a pivotal approach in providing rapid and convenient medical diagnostics. Smartphone-based solutions further augment the accessibility and ease of POC, enabling efficient on-the-go analysis. The integration of smartphone technology with POC has paved the way for innovative applications such as the Vivoo App, which empowers users to monitor various health parameters conveniently. Our study validated the accuracy and reliability of the smartphone-based POC urinalysis Vivoo mobile application. A comparative approach was followed wherein artificial urine samples were analyzed using both the Vivoo and traditional laboratory methods. A diverse range of health parameters were assessed. A total of 2618 strips were used over the course of this study to evalate the accuracy of Vivoo. The test strips results appeared to match exactly the expected measurement results. In addition, when the ±1 color block acceptance criterion was applied, 2608 of 2618 measurements of the tested strips were found to have met the expected measurement results completely. Based on the results, the 95% confidence interval for the exact match agreement proportion of Vivoo is 87.55% ± 1.27% and 99.62% ± 0.24%. As a wellness product, this study thus concludes that the Vivoo is appropriate in terms of both device reliability and performance. The app's ability to provide accurate and timely health results offers promising opportunities to improve individual health management.

Label/immobilization-free Cas12a-based electrochemiluminescence biosensor for sensitive DNA detection

Electrochemiluminescence (ECL) is one of the most sensitive techniques in the field of diagnostics. However, they typically require luminescent labeling and electrode surface biological modification, which is a time-consuming and laborious process involving multiple steps and may also lead to low reaction efficiency. Fabricating label/modification-free biosensors has become one of the most attractive parts for simplifying the ECL assays. In this work, the ECL luminophores carbon dots (CDs) were encapsulated in DNA hydrogel in situ by a simple rolling circle amplification (RCA) reaction. Upon binding of the target DNA, active Cas12a induces a collateral cleavage of the hydrogel's ssDNA backbone, resulting in a programmable degradation of the hydrogel and the release of CDs. By directly measuring the released CDs ECL, a simple and rapid label/modification-free detection of the target HPV-16 was realized. It is noted that this method allowed for 0.63 pM HPV-16 DNA detection without any amplification step, and it could take only ∼60 min for a fast test of a human serum sample. These results showed that our label/modification-free ECL biosensor has great potential for use in simple, rapid, and sensitive point-of-care (POC) detection.

Evaluation of a Revised Point-of-Care Test for the Detection of Feline Leukaemia p27 Antigen and Anti-p15E Antibodies in Cats.

The first point-of-care (PoC) test (v-RetroFel®; modified version 2021) determining the presence of FeLV p27 antigen and FeLV anti-p15E antibodies has become recently commercially available to identify different feline leukaemia virus (FeLV) infection outcomes. This study aimed to assess this PoC test's performance concerning FeLV p27 antigen and FeLV anti-p15E antibody detection. Sensitivity, specificity, positive and negative predictive values (PPV, NPV) were assessed after ten minutes (recommended) and 20 min (prolonged) incubation times. The test results were evaluated as either positive or negative. Serum samples from 934 cats were included, originating from Italy (n = 269), Portugal (n = 240), Germany (n = 318), and France (n = 107). FeLV p27 antigen and anti-p15E antibodies were measured by reference standard ELISAs and compared to the PoC test results. The PoC test was easy to perform and the results easy to interpret. Sensitivity and specificity for FeLV p27 antigen were 82.8% (PPV: 57.8%) and 96.0% (NPV: 98.8%) after both, ten and 20 minues of incubation time. Sensitivity and specificity for anti-p15E antibodies were 31.4% (PPV: 71.6%) and 96.9% (NPV: 85.1%) after ten minutes incubation time; sensitivity was improved by a prolonged incubation time (20 min) to 40.0% (PPV: 76.3%), while specificity remained the same (96.9%, NPV: 86.7%). Despite the improved sensitivity using the prolonged incubation time, lower than ideal sensitivities for both p27 antigen and especially anti-p15E antibodies were found, indicating that the PoC test in its current version needs further improvement prior to application in the field.

Specific and Magnetic Covalent Organic Framework Confined Os Nanoclusterzyme for Interference‐Free and Ultrasensitive Biosensing

AbstractThe peroxidase (POD)‐mimic nanozymes can be a potential tool for point‐of‐care (POC) diseases diagnosis. However, the complex sample matrix and unspecific multiple‐enzyme activities of nanozyme can generate false background signal and decrease the diagnostic accuracy. Here, a magnetic and POD‐specific covalent organic framework (COF) confined osmium (Os) nanoclusterzyme Fe3O4@COF@Os is developed for biomarkers biosensing. First, found that the catalytic activity and specificity of Fe3O4@COF@Os can be regulated by the deoxidizers and the functional groups of COF ligands. By using ascorbic acid as deoxidizer and F functional COF ligands, Fe3O4@COF@Os displayed superior POD‐specific activity and negligible oxidase (OXD) and catalase (CAT) mimic activity. Therefore, Fe3O4@COF@Os can separate and analyze of targets in bio‐matrix without background interference. For application, Fe3O4@COF@Os based lateral flow assay is established for serum cancer biomarker prostate‐specific antigen, the detection limit is 3.83 pg mL−1. For clinical prostatic cancer samples, the accuracy is 100% with a correlation coefficient of 0.998 with commercial ELISA kit. For chronic disease biomarker sensing, salivary glucose can be quantified as low as 0.1 µm, with negligible background interference and favorable recyclability. This specific magnetic nanozymes can offer a promising pretreatment‐free and POC strategy for rapid and accurate diseases diagnosis.

Towards quantifying biomarkers for respiratory distress in preterm infants: Machine learning on mid infrared spectroscopy of lipid mixtures

Neonatal respiratory distress syndrome (nRDS) is a challenging condition to diagnose which can lead to delays in receiving appropriate treatment. Mid infrared (IR) spectroscopy is capable of measuring the concentrations of two diagnostic nRDS biomarkers, lecithin (L) and sphingomyelin (S) with the potential for point of care (POC) diagnosis and monitoring. The effects of varying other lipid species present in lung surfactant on the mid IR spectra used to train machine learning models are explored. This study presents a lung lipid model of five lipids present in lung surfactant and varies each in a systematic approach to evaluate the ability of machine learning models to predict the lipid concentrations, the L/S ratio and to quantify the uncertainty in the predictions using the jackknife + -after-bootstrap and variant bootstrap methods. We establish the L/S ratio can be determined with an uncertainty of approximately ±0.3 mol/mol and we further identify the 5 most prominent wavenumbers associated with each machine learning model.

Clinical validation of SARS-CoV-2 electrochemical immunosensor based on the spike-ACE2 complex

Background and aimsAdvances in health, especially in prevention, diagnosis, and treatment, have significantly impacted the way of facing emerging infectious diseases. Yet, events such as the COVID-19 pandemic have shown that there is still a long way to go. Therefore, an urgent need exists for portable and easily deployable point-of-care (POC) detection tools. Biosensors at the POC remain in the laboratory in an analytical characterization step and are not yet mature enough to reach the market massively. In this context, it is necessary to progress in validating these devices to demonstrate their relevance in detecting different disease biomarkers. This work reports on the clinical validation of an electrochemical immunosensor for detecting SARS-CoV-2. MethodsA monocentric retrospective cohort study was conducted with 150 random nasopharyngeal swabs or tracheal aspiration samples tested by RT-PCR. The immunosensor based on magnetic beads and chronoamperometry detected SARS-CoV-2 through the spike-angiotensin-converting protein (ACE2) immunocomplex. ResultsThis biosensor demonstrated 96.04 % clinical sensitivity and 87.75 % clinical specificity in detecting SARS-CoV-2 in the samples, highly correlated with the RT-PCR gold standard. ConclusionsIt demonstrates the potential of electrochemical biosensors to be implemented as highly sensitive and easily deployable detection strategies even in remote locations.

Precision and accuracy of a point of care glucometer for detection of hypoglycaemia in horses

Point-of-care (POC) glucometry is commonly used in horses; however, measurement error with this method when analysing hypoglycaemic samples (<4 mmol/L) is unknown. The objective of this study was to determine the precision and accuracy of glucometry in hypoglycaemic horses in comparison to a laboratory method of glucose measurement (LAB). Repeatability coefficients were 0.47 mmol/L for POC and 0.09 mmol/L for LAB, and coefficients of variation were 10 % and 2.11 %, for the POC and LAB methods, respectively. Systemic bias with the POC method was present, with a mean bias of −0.26 mmol/L (95 % limits of agreement: −0.88 – 0.37) in comparison to LAB, and <70% of measurements were within 20 % of paired LAB results. Prior to use of glucometers, assessment of the diagnostic performance of the equipment is necessary, including determination of acceptable criteria and reference ranges for hypoglycaemic samples.

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