Current territorial organization for access to revascularization therapies for acute ischemic stroke in the Veneto region (Italy) from 2017 to 2021.

INTRODUCTION: To evaluate the access to treatments with intravenous thrombolysis (IVT) and/or mechanical thrombectomy (MT) in acute ischemic stroke patients admitted to stroke units (SUs) of Veneto region (Italy) according to current "hub-and-spoke" model from 2017 to 2021. PATIENTS AND METHODS: We retrospectively analyzed data on treatments with IVT and/or MT for stroke patients admitted to the 23 SUs (6 Hubs and 17 Spokes) of the 6 macro-areas including 9 local sanitary units (LSUs) and 2 hospitals. RESULTS: We reported 6093 treatments with IVT alone, 1114 with IVT plus MT, and 921 with MT alone. Number of stroke unit (SU) beds/100,000 inhabitants ranges from 2.3 to 2.8, and no difference was found among different macro-areas. Number of treatments/100,000 inhabitants/year ranges from 19 to 34 for IVT alone, from 2 to 7 for IVT plus MT, and from 2 to 5 for MT alone. Number of IVT alone/SU bed/year ranges from 9 to 21 in the Hub and from 6 to 12 in the Spokes. Rate of IVT plus MT in patients directly arrived in the same LSU's Hub ranges from 50 to 81%, likewise the one of MT alone ranges from 49 to 84%. CONCLUSIONS: Treatment target rates of IVT and MT set by Action Plan for Stroke in Europe 2018-2030 has been globally exceeded in the Veneto region. However, the target rate of MT and access revascularization treatments is heterogeneous among different macro-areas. Further efforts should be made to homogenize the current territorial organization.

Detection of SARS-CoV-2 Virus by Triplex Enhanced Nucleic Acid Detection Assay (TENADA).

SARS-CoV-2, a positive-strand RNA virus has caused devastating effects. The standard method for COVID diagnosis is based on polymerase chain reaction (PCR). The method needs expensive reagents and equipment and well-trained personnel and takes a few hours to be completed. The search for faster solutions has led to the development of immunological assays based on antibodies that recognize the viral proteins that are faster and do not require any special equipment. Here, we explore an innovative analytical approach based on the sandwich oligonucleotide hybridization which can be adapted to several biosensing devices including thermal lateral flow and electrochemical devices, as well as fluorescent microarrays. Polypurine reverse-Hoogsteen hairpins (PPRHs) oligonucleotides that form high-affinity triplexes with the polypyrimidine target sequences are used for the efficient capture of the viral genome. Then, a second labeled oligonucleotide is used to detect the formation of a trimolecular complex in a similar way to antigen tests. The reached limit of detection is around 0.01 nM (a few femtomoles) without the use of any amplification steps. The triplex enhanced nucleic acid detection assay (TENADA) can be readily adapted for the detection of any pathogen requiring only the knowledge of the pathogen genome sequence.

Acute revascularization treatments for ischemic stroke in the Stroke Units of Triveneto, northeast Italy: time to treatment and functional outcomes.

It is not known whether the current territorial organization for acute revascularization treatments in ischemic stroke patients guarantees similar time to treatment and functional outcomes among different levels of institutional stroke care. We aimed to assess the impact of time to treatment on functional outcomes in ischemic stroke patients who received intravenous thrombolysis (IVT) alone, bridging (IVT plus thrombectomy), or primary thrombectomy in level 1 and level 2 Stroke Units (SUs) in Triveneto, a geographical macroarea in Northeast of Italy. We conducted an analysis of data prospectively collected from 512 consecutive ischemic stroke patients who received IVT and/or mechanical thrombectomy in 25 SUs from September 17th to December 9th 2018. The favorable outcome measures were mRS score 0-1 and 0-2 at 3 months. The unfavorable outcome measures were mRS score 3-5 and death at 3 months. We estimated separately the possible association of each variable for time to treatment (onset-to-door, door-to-needle, onset-to-needle, door-to-groin puncture, needle-to-groin puncture, and onset-to-groin puncture) with 3-month outcome measures by calculating the odds ratios (ORs) with two-sided 95% confidence intervals (CI) after adjustment for pre-defined variables and variables with a probability value ≤ 0.10 in the univariate analysis for each outcome measure. Distribution of acute revascularization treatments was different between level 1 and level 2 SUs (p < 0.001). Among 182 patients admitted to level 1 SUs (n = 16), treatments were IVT alone in 164 (90.1%), bridging in 12 (6.6%), and primary thrombectomy in 6 (3.3%) patients. Among 330 patients admitted to level 2 SUs (n = 9), treatments were IVT alone in 219 (66.4%), bridging in 74 (22.4%), and primary thrombectomy in 37 (11.2%) patients. Rates of excellent outcome (51.4% vs 45.9%), favorable outcome (60.1% vs 58.7%), unfavorable outcome (33.3% vs 33.8%), and death (9.8% vs 11.3%) at 3 months were similar between level 1 and 2 SUs. No significant association was found between time to IVT alone (onset-to-door, door-to-needle, and onset-to-needle) and functional outcomes. After adjustment, door-to-needle time ≤ 60 min (OR 4.005, 95% CI 1.232-13.016), shorter door-to-groin time (OR 0.991, 95% CI 0.983-0.999), shorter needle-to-groin time (OR 0.986, 95% CI 0.975-0.997), and shorter onset-to-groin time (OR 0.994, 95% CI 0.988-1.000) were associated with mRS 0-1. Shorter door-to-groin time (OR 0.991, 95% CI 0.984-0.998), door-to-groin time ≤ 90 min (OR 12.146, 95% CI 2.193-67.280), shorter needle-to-groin time (OR 0.983, 95% CI 0.972-0.995), and shorter onset-to-groin time (OR 0.993, 95% CI 0.987-0.999) were associated with mRS 0-2. Longer door-to-groin time (OR 1.007, 95% CI 1.001-1.014) and longer needle-to-groin time (OR 1.019, 95% CI 1.005-1.034) were associated with mRS 3-5, while door-to-groin time ≤ 90 min (OR 0.229, 95% CI 0.065-0.808) was inversely associated with mRS 3-5. Longer onset-to-needle time (OR 1.025, 95% CI 1.002-1.048) was associated with death. Times to treatment influenced the 3-month outcomes in patients treated with thrombectomy (bridging or primary). A revision of the current territorial organization for acute stroke treatments in Triveneto is needed to reduce transfer time and to increase the proportion of patients transferred from a level 1 SU to a level 2 SU to perform thrombectomy.

Stroke management during the coronavirus disease 2019 (COVID-19) pandemic: experience from three regions of the north east of Italy (Veneto, Friuli-Venezia-Giulia, Trentino-Alto-Adige).

BACKGROUND: Efficiency of care chain response and hospital reactivity were and are challenged for stroke acute care management during the pandemic period of coronavirus disease 2019 (COVID-19) in North-Eastern Italy (Veneto, Friuli-Venezia-Giulia, Trentino-Alto-Adige), counting 7,193,880 inhabitants (ISTAT), with consequences in acute treatment for patients with ischemic stroke. METHODS: We conducted a retrospective data collection of patients admitted to stroke units eventually treated with thrombolysis and thrombectomy, ranging from January to May 2020 from the beginning to the end of the main first pandemic period of COVID-19 in Italy. The primary endpoint was the number of patients arriving to these stroke units, and secondary endpoints were the number of thrombolysis and/or thrombectomy. Chi-square analysis was used on all patients; furthermore, patients were divided into two cohorts (pre-lockdown and lockdown periods) and the Kruskal-Wallis test was used to test differences on admission and reperfusive therapies. RESULTS: In total, 2536 patients were included in 22 centers. There was a significant decrease of admissions in April compared to January. Furthermore, we observed a significant decrease of thrombectomy during the lockdown period, while thrombolysis rate was unaffected in the same interval across all centers. CONCLUSIONS: Our study confirmed a decrease in admission rate of stroke patients in a large area of northern Italy during the lockdown period, especially during the first dramatic phase. Overall, there was no decrease in thrombolysis rate, confirming an effect of emergency care system for stroke patients. Instead, the significant decrease in thrombectomy rate during lockdown addresses some considerations of local and regional stroke networks during COVID-19 pandemic evolution.

Electrochemical Paper-Based Biosensor Devices for Rapid Detection of Biomarkers.

In healthcare, new diagnostic tools that help in the diagnosis, prognosis, and monitoring of diseases rapidly and accurately are in high demand. For in-situ measurement of disease or infection biomarkers, point-of-care devices provide a dramatic speed advantage over conventional techniques, thus aiding clinicians in decision-making. During the last decade, paper-based analytical devices, combining paper substrates and electrochemical detection components, have emerged as important point-of-need diagnostic tools. This review highlights significant works on this topic over the last five years, from 2015 to 2019. The most relevant articles published in 2018 and 2019 are examined in detail, focusing on device fabrication techniques and materials applied to the production of paper fluidic and electrochemical cell architectures as well as on the final device assembly. Two main approaches were identified, that are, on one hand, those ones where the fabrication of the electrochemical cell is done on the paper substrate, where the fluidic structures are also defined, and, on the other hand, the fabrication of those ones where the electrochemical cell and liquid-driving paper component are defined on different substrates and then heterogeneously assembled. The main limitations of the current technologies are outlined and an outlook on the current technology status and future prospects is given.

Serum Interleukin-10 Levels Correlate with Cerebrospinal Fluid Amyloid Beta Deposition in Alzheimer Disease Patients.

BACKGROUND AND OBJECTIVE: In Alzheimer disease (AD) inflammation becomes evident throughout the course of the disease. However, the association between inflammation, cognitive impairment, and cerebrospinal biomarkers (Aß42, t-tau, p-tau181, and Aß42/p-tau181 ratio) is poorly understood. METHODS: A large panel of inflammatory cytokines (interleukin [IL]-1ß, IL-1ra, IL-2, IL-4, IL-6, IL-10, IL-17, interferon-γ, tumor necrosis factor-α, and vascular endothelial growth factor) was analyzed using a multiplex immunoassay in 27 patients with a diagnosis of AD dementia and in 18 control subjects. In a subgroup with available cerebrospinal fluid (CSF) samples, cytokines in serum were correlated with the levels of neurodegenerative CSF biomarkers (Aß42, t-tau, p-tau181, and Aß42/p-tau181 ratio). RESULTS: Compared to control subjects, AD patients showed a significant upregulation of IL-10, IL-1ß, and IL-17 serum levels. Several cytokines appeared intercorrelated, and IL-10 in particular presented a significant inverse correlation with CFS levels of Aß42 and the Aß42/p-tau ratio. CONCLUSION: Our findings indicate that serum levels of IL-10 may represent a possible peripheral expression of amyloid beta deposition in AD patients.

Prestroke CHA2DS2-VASc Score and Severity of Acute Stroke in Patients with Atrial Fibrillation: Findings from RAF Study.

BACKGROUND AND PURPOSE: The aim of this study was to investigate for a possible association between both prestroke CHA2DS2-VASc score and the severity of stroke at presentation, as well as disability and mortality at 90 days, in patients with acute stroke and atrial fibrillation (AF). METHODS: This prospective study enrolled consecutive patients with acute ischemic stroke, AF, and assessment of prestroke CHA2DS2-VASc score. Severity of stroke was assessed on admission using the National Institutes of Health Stroke Scale (NIHSS) score (severe stroke: NIHSS ≥10). Disability and mortality at 90 days were assessed by the modified Rankin Scale (mRS <3 or ≥3). Multiple logistic regression was used to correlate prestroke CHA2DS2-VASc and severity of stroke, as well as disability and mortality at 90 days. RESULTS: Of the 1020 patients included in the analysis, 606 patients had an admission NIHSS score lower and 414 patients higher than 10. At 90 days, 510 patients had mRS ≥3. A linear correlation was found between the prestroke CHA2DS2-VASc score and severity of stroke (P = .001). On multivariate analysis, CHA2DS2-VASc score correlated with severity of stroke (P = .041) and adverse functional outcome (mRS ≥3) (P = .001). A logistic regression with the receiver operating characteristic graph procedure (C-statistics) evidenced an area under the curve of .60 (P = .0001) for severe stroke. Furthermore, a correlation was found between prestroke CHA2DS2-VASc score and lesion size. CONCLUSIONS: In patients with AF, in addition to the risk of stroke, a high CHA2DS2-VASc score was independently associated with both stroke severity at onset and disability and mortality at 90 days.

Early Recurrence and Cerebral Bleeding in Patients With Acute Ischemic Stroke and Atrial Fibrillation: Effect of Anticoagulation and Its Timing: The RAF Study.

BACKGROUND AND PURPOSE: The best time for administering anticoagulation therapy in acute cardioembolic stroke remains unclear. This prospective cohort study of patients with acute stroke and atrial fibrillation, evaluated (1) the risk of recurrent ischemic event and severe bleeding; (2) the risk factors for recurrence and bleeding; and (3) the risks of recurrence and bleeding associated with anticoagulant therapy and its starting time after the acute stroke. METHODS: The primary outcome of this multicenter study was the composite of stroke, transient ischemic attack, symptomatic systemic embolism, symptomatic cerebral bleeding and major extracranial bleeding within 90 days from acute stroke. RESULTS: Of the 1029 patients enrolled, 123 had 128 events (12.6%): 77 (7.6%) ischemic stroke or transient ischemic attack or systemic embolism, 37 (3.6%) symptomatic cerebral bleeding, and 14 (1.4%) major extracranial bleeding. At 90 days, 50% of the patients were either deceased or disabled (modified Rankin score ≥3), and 10.9% were deceased. High CHA2DS2-VASc score, high National Institutes of Health Stroke Scale, large ischemic lesion and type of anticoagulant were predictive factors for primary study outcome. At adjusted Cox regression analysis, initiating anticoagulants 4 to 14 days from stroke onset was associated with a significant reduction in primary study outcome, compared with initiating treatment before 4 or after 14 days: hazard ratio 0.53 (95% confidence interval 0.30-0.93). About 7% of the patients treated with oral anticoagulants alone had an outcome event compared with 16.8% and 12.3% of the patients treated with low molecular weight heparins alone or followed by oral anticoagulants, respectively (P=0.003). CONCLUSIONS: Acute stroke in atrial fibrillation patients is associated with high rates of ischemic recurrence and major bleeding at 90 days. This study has observed that high CHA2DS2-VASc score, high National Institutes of Health Stroke Scale, large ischemic lesions, and type of anticoagulant administered each independently led to a greater risk of recurrence and bleedings. Also, data showed that the best time for initiating anticoagulation treatment for secondary stroke prevention is 4 to 14 days from stroke onset. Moreover, patients treated with oral anticoagulants alone had better outcomes compared with patients treated with low molecular weight heparins alone or before oral anticoagulants.

Engineering a Point-of-Care Paper-Microfluidic Electrochemical Device Applied to the Multiplexed Quantitative Detection of Biomarkers in Sputum.

Health initiatives worldwide demand affordable point-of-care devices to aid in the reduction of morbidity and mortality rates of high-incidence infectious and noncommunicable diseases. However, the production of robust and reliable easy-to-use diagnostic platforms showing the ability to quantitatively measure several biomarkers in physiological fluids and that could in turn be decentralized to reach any relevant environment remains a challenge. Here, we show the particular combination of paper-microfluidic technology, electrochemical transduction, and magnetic nanoparticle-based immunoassay approaches to produce a unique, compact, and easily deployable multiplex device to simultaneously measure interleukin-8, tumor necrosis factor-α, and myeloperoxidase biomarkers in sputum, developed with the aim of facilitating the timely detection of acute exacerbations of chronic obstructive pulmonary disease. The device incorporates an on-chip electrochemical cell array and a multichannel paper component, engineered to be easily aligned into a polymeric cartridge and exchanged if necessary. Calibration curves at clinically relevant biomarker concentration ranges are produced in buffer and artificial sputum. The analysis of sputum samples of healthy individuals and acutely exacerbated patients produces statistically significant biomarker concentration differences between the two studied groups. The device can be mass-produced at a low cost, being an easily adaptable platform for measuring other disease-related target biomarkers.

Systemic thrombolysis in patients with acute ischemic stroke and Internal Carotid ARtery Occlusion: the ICARO study.

BACKGROUND AND PURPOSE: The beneficial effect of intravenous thrombolytic therapy in patients with acute ischemic stroke attributable to internal carotid artery (ICA) occlusion remains unclear. The aim of this study was to evaluate the efficacy and safety of intravenous recombinant tissue-type plasminogen activator in these patients. METHODS: ICARO was a case-control multicenter study on prospectively collected data. Patients with acute ischemic stroke and ICA occlusion treated with intravenous recombinant tissue-type plasminogen activator within 4.5 hours from symptom onset (cases) were compared to matched patients with acute stroke and ICA occlusion not treated with recombinant tissue-type plasminogen activator (controls). Cases and controls were matched for age, gender, and stroke severity. The efficacy outcome was disability at 90 days assessed by the modified Rankin Scale, dichotomized as favorable (score of 0-2) or unfavorable (score of 3-6). Safety outcomes were death and any intracranial bleeding. RESULTS: Included in the analysis were 253 cases and 253 controls. Seventy-three cases (28.9%) had a favorable outcome as compared with 52 controls (20.6%; adjusted odds ratio (OR), 1.80; 95% confidence interval [CI], 1.03-3.15; P=0.037). A total of 104 patients died, 65 cases (25.7%) and 39 controls (15.4%; adjusted OR, 2.28; 95% CI, 1.36-3.22; P=0.001). There were more fatal bleedings (2.8% versus 0.4%; OR, 7.17; 95% CI, 0.87-58.71; P=0.068) in the cases than in the controls. CONCLUSIONS: In patients with stroke attributable to ICA occlusion, thrombolytic therapy results in a significant reduction in the proportion of patients dependent in activities of daily living. Increases in death and any intracranial bleeding were the trade-offs for this clinical benefit.

Experimental image dataset for validation of the noise-induced bias that affects Digital Image Correlation.

The present article shares with the scientific community several image sets used for experimentally validating the noise-induced bias on different Digital Image Correlation (DIC) formulations, as reported in Baldi et al. [1]. These sets are provided with a description of the experimental setup used for image acquisition. The basic idea is to acquire a series of images obtained by rigidly translating the target, where incremental displacement is of the order of a small fraction of a pixel. This condition requires a high-precision control of the target position through the tests. Moreover, the noise content of each image set is modulated using a statistical approach that uncouples the intensity field from the standard deviation. Lastly, the images are acquired with different exposure conditions to analyze the gray tone gradient effect on noise-induced bias.

Compact Microfluidic Platform with LED Light-Actuated Valves for Enzyme-Linked Immunosorbent Assay Automation.

Lab-on-a-chip devices incorporating valves and pumps can perform complex assays involving multiple reagents. However, the instruments used to drive these chips are complex and bulky. In this article, a new wax valve design that uses light from a light emitting diode (LED) for both opening and closing is reported. The valves and a pumping chamber are integrated in lab-on-a-foil chips that can be fabricated at low cost using rapid prototyping techniques. A chip for the implementation of enzyme-linked immunosorbent assays (ELISA) is designed. A porous nitrocellulose material is used for the immobilization of capture antibodies in the microchannel. A compact generic instrument with an array of 64 LEDs, a linear actuator to drive the pumping chamber, and absorbance detection for a colorimetric readout of the assay is also presented. Characterization of all the components and functionalities of the platform and the designed chip demonstrate their potential for assay automation.

Electrical readout of protein microarrays on regular glass slides.

A new approach for the electrical readout of microarrays prepared on regular glass slides, using an array of impedimetric transducers (interdigitated electrodes, IDEs) is presented in this work. Impedance detection relies on the use of a urease-labeled immunoassay scheme. Urease is able to produce an increase in conductivity by hydrolysis of the urea substrate, which is measured with the IDEs and directly related to the amount of target analyte. Unlike previous electrical microarrays, the assay does not take place on top of the transducers but on a regular glass slide, which may enable the development of compact multiplexed analytical systems with lower cost per assay. A droplet of solution with the enzymatic substrate is deposited on each transducer of the array, and the microarray is positioned at a short distance (300 µm) so that each droplet wets one transducer and one spot of the microarray. This procedure allows reusing the transducer array for readout of a virtually unlimited number of microarrays. A microarray based on an immunoassay for the detection of a mouse generic protein in a concentration range from 0.03 to 30 µg mL(-1) was carried out to assess the performance of the electrical readout approach. A sigmoid response with a limit of detection of 0.1 µg mL(-1) and a dynamic range of 1 order of magnitude was obtained. A comparative study was also carried out with two well established analytical procedures. First, the urease-based immunoassay was tested in a 96 well microtiter plate using phenol red pH indicator and absorbance detection. Second, the microarray was carried out using the same target protein concentration range but applying a Cy3 label and fluorescence detection. Both assays allowed for the validation of the performance of the presented electrical readout system.

Risk of recurrent cerebrovascular events in patients with cryptogenic stroke or transient ischemic attack and patent foramen ovale: the FORI (Foramen Ovale Registro Italiano) study.

BACKGROUND: The optimal management of patients with cryptogenic ischemic stroke found to have a patent foramen ovale (PFO) at diagnostic workup remains unclear. The aims of this observational multicenter study were to evaluate: (1) the risk of recurrent cerebrovascular events in patients with cryptogenic minor ischemic stroke or transient ischemic attack (TIA) and PFO who either underwent percutaneous PFO closure or received only medical treatment, and (2) the risk factors associated with recurrent events. METHODS: Consecutive patients (aged 55 years or less) with first-ever cryptogenic minor ischemic stroke or TIA and PFO were recruited in 13 Italian hospitals between January 2006 and September 2007 and followed up for 2 years. RESULTS: 238 patients were included in the study (mean age 42.2 ± 10.0 years; 118 males); 117 patients (49.2%) received only antithrombotic therapy while 121 patients underwent percutaneous PFO closure (50.8%). Stroke as the qualifying event was more common in the medical treatment group (p = 0.01). The presence of atrial septal aneurysm and evidence of 20 bubbles or more on transcranial Doppler were more common in the PFO closure group (p = 0.002 and 0.02). Eight patients (6.6%) experienced a nonfatal complication during PFO closure. At the 2-year follow-up, 17 recurrent events (TIA or stroke; 3.6% per year) were observed; 7 of these events (2.9% per year) occurred in the percutaneous PFO closure group and 10 events (4.2% per year) in the medical treatment group. The rate of recurrent stroke was 0.4% per year in patients who underwent percutaneous closure (1 event) and 3.4% per year in patients who received medical treatment (8 events). On multivariate analysis, percutaneous closure was not protective in preventing recurrent TIA or stroke (OR = 0.1, 95% CI = 0.02-1.5, p = 0.1), while it was barely protective in preventing recurrent stroke (OR = 0.1, 95% CI = 0.0-1.0, p = 0.053). CONCLUSIONS: The results of this observational, nonrandomized study suggest that PFO closure might be superior to medical therapy for the prevention of recurrent stroke. Periprocedural complications were the trade-off for this clinical benefit. Controlled randomized clinical trials comparing percutaneous closure with medical management are required.

Towards fully integrated wireless impedimetric sensors.

We report on the design and characterization of the building blocks of a single-chip wireless chemical sensor fabricated with a commercial complementary metal-oxide-silicon (CMOS) technology, which includes two types of transducers for impedimetric measurements (4-electrode array and two interdigitated electrodes), instrumentation circuits, and a metal coil and circuits for inductive power and data transfer. The electrodes have been formed with a polycrystalline silicon layer of the technology by a simple post-process that does not require additional deposition or lithography steps, but just etching steps. A linear response to both conductivity and permittivity of solutions has been obtained. Wireless communication of the sensor chip with a readout unit has been demonstrated. The design of the chip was prepared for individual block characterization and not for full system characterization. The integration of chemical transducers within monolithic wireless platforms will lead to smaller, cheaper, and more reliable chemical microsensors, and will open up the door to numerous new applications where liquid mediums that are enclosed in sealed receptacles have to be measured.

Selective detection of live pathogens via surface-confined electric field perturbation on interdigitated silicon transducers.

Detection of physical changes of cells is emerging as a new diagnostic approach to determine their phenotypical features. One of such changes is related to their viability; live (viable) cells are more voluminous than the dead ones, and monitoring this parameter in tissue cells becomes essential in fields such as drug discovery and hazard evaluation. In the area of pathogen detection, an analytical system capable of specifically detecting viable cells with the simple sample preparation and detection process would be highly desirable since live microorganisms can rapidly increase their numbers even at extremely low concentration and become a severe health risk. However, current sensing strategies cannot clearly determine the viability of cells, and hence they are susceptible to false-positive signals from harmless dead pathogens. Here we developed a robust electronic immunoassay that uses a pair of polycrystalline silicon interdigitated electrodes for the rapid detection of pathogens with high specificity for live cells. After bacterial cells were specifically anchored to the surface of the antibody-modified electrode, the characteristic geometry of the transducer enables the selective detection of viable cells with a limit of detection of 3 x 10(2) cfu/mL and an incubation time of only 1 h. The CMOS compatible fabrication process of the chip along with the label-free, reagent-less electronic detection and the easy electrode regeneration to recycle for another impedance measurement make this approach an excellent candidate for oncoming economical in-field viable-cell detection systems, fully integrable with sophisticated signal processing circuits.

Single-cell pathogen detection with a reverse-phase immunoassay on impedimetric transducers.

The risk of infectious diseases has compelled some industries to establish a zero-tolerance standard for the presence of microorganisms in a given sample. Here, we address this issue with a novel reverse-phase immunoassay on impedimetric transducers for the specific detection of extremely low numbers of pathogens (less than 10 cells). After simply spotting the sample onto the electrodes, physisorbed analytes were targeted with urease-labeled antibodies, and the urease on the pathogens hydrolyzed urea to ionic species with a concomitant decrease of the resistivity of the solution. By this methodology, the limit of detection (LOD) based on the 3sigma criterion was 1 Escherichia coli cell with an assay time under 1 h. However, the precise number of cells present in highly diluted samples is uncertain, making it difficult to assess the final LOD of the sensor. We overcome this problem by using an atomic force microscope to deposit and image in situ the exact number cells on the transducer. After performing the immunoassay, a single E. coli cell was successfully detected without ambiguity in the number of cells even in the presence of a 10(4) excess of a competing microorganism, thus demonstrating the outstanding LOD and selectivity of the proposed reverse-phase immunoassay.

Label-free cancer cell detection with impedimetric transducers.

While cancer is still an implacable disease, many cancers can be cured if they are diagnosed in an early stage. Recently, it was reported that the transformation from normal cells to cancer cells can change their mechanoelastic properties to become softer and more deformable. If some cancer cells are more deformable, then a progressive increase of the volume of softer cancer cells should be induced as an abrupt change in osmolarity is applied. On the basis of this hypothesis, we developed a sensor that can electronically monitor the volume increase of cancer cells under hyposmotic pressure. By this methodology, K:Molv NIH 3T3 cells, 786-O human kidney carcinoma cells, and MPSC-1 ovarian cancer cells were successfully detected within 30 min using on the order of 10 cells. These cancer cells could be detected with the same sensitivity even in the presence of a vast excess of the respective noncancerous cells [NIH 3T3 cells, human embryonic kidney (HEK) 293 cells, ovarian surface epithelial (OSE) cells]. Since the proposed impedimetric sensor could be useful for detecting cancer cells fast and reliably, it could be further implemented in the screening of large populations of tissue samples and the detection of circulating tumor cells for point-of-care applications.