Antibodies fragments as enablers of cardiac troponin (cTn) detection with extended gate metal-oxide-semiconductor field effect transistors (EGFET)

Background

Cardiac troponin is the gold standard biomarker used to rule in or out acute myocardial infarction (AMI) in patients. Highly sensitive and reliable detection mechanisms for this important biomarker are required for advancing the field of early detection in medical applications. Field effect transistor (FET) sensors, specifically functionalised with troponin antibodies, can perform specific detection of cardiac troponin I or T, with high sensitivity and low limit of detection (LoD), in fully scalable and low power operated intelligent sensing systems.

Purpose

To design and realize a new wearable blood or sweat on-chip sensor, able to perform a real-time reliable detection of the cardiac troponin level in a patient suffering of AMI symptoms or during the post-operative phase. The sensor exploits the voltammetric detection of biomarkers, and offers the potential for miniaturization and reduced hospitalization costs.

Methods

Electrical current modulation in field effect transistor-based sensors is used as transducing principle, as a result of the surface potential change following exposure to biological fluids containing different concentrations of antigens. The use of antibodies fragments, properly attached to the sensor surface, enhances the sensitivity. Proof of concept tests involve the detection of fluorescein.

Results

The specific antigen detection by means of an electrical measurement has been proved, with a detection limit of <1 nM (24ng/mL), linear range over one decade and a sensitivity around 70mV/decade. Fluorescein antibodies fragments, commercially purchased, were attached to the gate of an EGFET device; the binding events between fluorescein molecules and the correspondent antibodies modify the electrical conduction properties of the transducer, creating a current shift whose amplitude is univocally related to the antigen concentration. The exploitation of the antibodies fragments allows the antigens to bind closer to the sensing surface, creating a more noticeable electrical perturbation. The device is made of a commercial Metal Oxide Semiconductor FET (MOSFET), whose gate is extended by a platinum electrode for sensing. The metal is then functionalised by attaching covalently antibodies fragments that act as probes for the antigens in the tested biofluids. Laboratory samples were prepared in house, using fluorescein as antigen. Concentrations between 45pM and 1uM have been tested, and the absence of non-specific binding has been successfully proved with bovine serum albumin (BSA), for which any noticeable response has been recorded.

Conclusion

We report an important step towards a real-time and reliable detection of cardiac troponin by means of nano-ISFETs, demonstrating the fluorescein antigens-antibodies specific binding. Further steps consists in correctly achieve a surface functionalisation with cardiac troponin I antibodies, and further enhance the sensor LoD.

Antigens detection with EGFET

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): Swiss National Science Foundation: ERA-NET, FLAG-ERA CONVERGENCE

Shape Coexistence at Zero Spin in ^{64}Ni Driven by the Monopole Tensor Interaction

The low-spin structure of the semimagic ^{64}Ni nucleus has been considerably expanded: combining four experiments, several 0^{+} and 2^{+} excited states were identified below 4.5 MeV, and their properties established. The Monte Carlo shell model accounts for the results and unveils an unexpectedly complex landscape of coexisting shapes: a prolate 0^{+} excitation is located at a surprisingly high energy (3463 keV), with a collective 2^{+} state 286 keV above it, the first such observation in Ni isotopes. The evolution in excitation energy of the prolate minimum across the neutron N=40 subshell gap highlights the impact of the monopole interaction and its variation in strength with N.

Special Article - The role of hand-held ultrasound for cardiopulmonary assessment during a pandemic

During the COVID-19 pandemic, we are likely to see a significant increase in the requests for rapid assessment of cardiac function, due to the frequent pre-existence of cardiac pathologies in patients admitted to hospital, and to the emergence of specific cardiac manifestations of this infection, such as myocarditis, sepsis related cardiomyopathy, stress induced cardiomyopathy and acute coronary syndromes. Hand-held, point-of-care ultrasound (HH-POCUS) is particularly suited for the provision of rapid, focused, integrated assessments of the heart and lungs. We present a review of the indications and protocols for focused HH-POCUS use in an acute setting and formulate proposals for streamlining their application in the COVID-19 context towards guiding optimum management of these patients while at the same time allowing adherence to robust infection control measures to provide safety to both the patient and our clinical staff.

Exchange Bias in Magnetic Topological Insulator Superlattices

Magnetic doping and proximity coupling can open a band gap in a topological insulator (TI) and give rise to dissipationless quantum conduction phenomena. Here, by combining these two approaches, we demonstrate a novel TI superlattice structure that is alternately doped with transition and rare earth elements. An unexpected exchange bias effect is unambiguously confirmed in the superlattice with a large exchange bias field using magneto-transport and magneto-optical techniques. Further, the Curie temperature of the Cr-doped layers in the superlattice is found to increase by 60 K compared to a Cr-doped single-layer film. This result is supported by density-functional-theory calculations, which indicate the presence of antiferromagnetic ordering in Dy:Bi2Te3 induced by proximity coupling to Cr:Sb2Te3 at the interface. This work provides a new pathway to realizing the quantum anomalous Hall effect at elevated temperatures and axion insulator state at zero magnetic field by interface engineering in TI heterostructures.

Electrokinetic transport and distribution of antibacterial nanoparticles for endodontic disinfection

AIM

To assess a novel, noninvasive intervention capable of mobilizing charged antibacterial nanoparticles to the apical portions of the root canal system, utilizing the principles of electrokinetics.

METHODS

Experiments were conducted in three stages. Stage-1: A computer model was generated to predict and visualize the electric field and current density distribution generated by the proposed intervention. Stage-2: Transport of chitosan nanoparticles (CSnp) was evaluated qualitatively using a transparent microfluidic model with fluorescent-labelled CSnp. Stage-3: An ex vivo model was utilized to study the antimicrobial efficacy of the proposed treatment against 3-week-old monospecies E. faecalis biofilms. Scanning electron microscopy (SEM) was also utilized in this stage to confirm the deposition of CSnp.

RESULTS

The results of the computer simulations predicted an electric field and current density that reach their maxima at the apical constriction of the root canal. Correspondingly, the microfluidic experiments demonstrated rapid, controlled CSnp transport throughout the simulated root canal anatomy with subsequent distribution and deposition in the apical constriction as well as periapical regions. Infected root canals when subjected to the novel treatment method resulted in a mean bacterial reduction of 2.1 log CFU. SEM analysis revealed electrophoretic deposition of chitosan nanoparticles onto the root canal dentine walls in the apical region.

CONCLUSION

The findings from this study demonstrate that the combination of cationic antibacterial nanoparticles with a low-intensity electric field results in particle transportation (electrophoresis) and deposition within the root canal. This results in a synergistic antibiofilm efficacy and has the potential to enhance root canal disinfection.

P900 The Heart Model: Automated LVEF calculation in the real world

Background

Heart Model (HM) is a proprietary, model-based algorithm for measurement of left ventricular ejection fraction (LVEF) in a 3D dataset acquired from an apical 4-chamber view by transthoracic echocardiography (TTE). There is evidence for superior reproducibility compared to 2D echo methods for LVEF measurement.

Objective

To assess the correlation of LVEF by HM with conventional, 2D LVEF methods.

Methods

All TTEs performed between 04-08/02/2019 by 2 HM-trained sonographers were included. Demographic characteristics, indication for TTE, LVEF by Simpson"s (LVEF_S), by "eyeballing" (LVEF_EB) and by HM (LVEF_HM), were recorded; LVEF for each study was also estimated by eye-balling by an experienced observer unaware of the reported LVEF (LVEF_IND). We compared LVEF by each method, their reciprocal correlations and their correlation with LVEF_HM. Image quality was rated excellent (endocardial border visible for all segments in the 3 apical views), good (< 1 segment was not visible / view), adequate (< 3 segments were not visible) and limited (<4 segments were not visible). Indications for TTE were: assessment of LVEF in 1/3 of the studies, murmurs in 1/5, and other indications in the rest.

Results

We included 74 patients (42 M, mean age (SD) 69.8(13.9), range 18-92 years). Forty-nine (66%) patients were in sinus rhythm, 23 (31%) were in AF, and the rest were in various paced rhythms. Fifty patients (68%) had excellent, good or adequate images. The EFs calculated by different methods are shown in the Table (p > 0.05 for all), an the Bland Altman plot (LVEF_EB vs HM) in the figure. LVEF_HM correlated modestly with the other methods if all studies were included (r = 0.535 LVEF_HM vs. LVEF_EB); the correlation improved if only good-quality studies were included (r = 0.769, p < 0.001 for both). All combinations of LVEF_IND, LVEF_EB and LVEF_S had correlation coefficients >0.93.

Conclusions

The Heart Model algorithm for LVEF measurement correlates well with traditional 2D methods in patients with good endocardial border definition, where its use can potentially improve reproducibility and reduce exam duration.

LVEF by method (good-quality studies) N = 50 Simpson"s Eyeballing HeartModel Independent Mean(%) 48.6 48.9 50.9 48.8 SD(%) 17.8 16.6 14.9 15.7 Median(%) 54.5 52.5 53 50 Range(%) 16-74 17.5-72.5 19-88 15-75 SD - standard deviation Independent - LVEF estimate (eyeballing) by independent observer unaware of reported EFs. LVEF_EB was chosen as it was available inall the reports.

Abstract P900 Figure. Bland Altman Plot (LVEF_EB vs LVEF_HM)

Detection of ultra-low protein concentrations with the simplest possible field effect transistor

Silicon nanowire (Si NW) sensors have attracted great attention due to their ability to provide fast, low-cost, label-free, real-time detection of chemical and biological species. Usually configured as field effect transistors (FETs), they have already demonstrated remarkable sensitivity with high selectivity (through appropriate functionalisation) towards a large number of analytes in both liquid and gas phases. Despite these excellent results, Si NW FET sensors have not yet been successfully employed to detect single molecules of either a chemical or biological target species. Here we show that sensors based on silicon junctionless nanowire transistors (JNTs), the simplest possible transistors, are capable of detecting the protein streptavidin at a concentration as low as 580 zM closely approaching the single molecule level. This ultrahigh detection sensitivity is due to the intrinsic advantages of junctionless devices over conventional FETs. Apart from their superior functionality, JNTs are much easier to fabricate by standard microelectronic processes than transistors containing p-n junctions. The ability of JNT sensors to detect ultra-low concentrations (in the zeptomolar range) of target species, and their potential for low-cost mass production, will permit their deployment in numerous environments, including life sciences, biotechnology, medicine, pharmacology, product safety, environmental monitoring and security.

The use of handheld ultrasound devices: a position statement of the European Association of Cardiovascular Imaging (2018 update)

Recent technological advances in echocardiography, with progressive miniaturization of ultrasound machines, have led to the development of handheld ultrasound devices (HUD). These devices, no larger than some mobile phones, can be used to perform partial, focused exams as an extension to the physical examination. The European Association of Cardiovascular Imaging (EACVI) acknowledges that the dissemination of appropriate HUD use is inevitable and desirable, because of its potential impact on patient management. However, as a scientific society of cardiac imaging, our role is to provide guidance in order to optimize patient benefit and minimize drawbacks from inappropriate use of this technology. This document provides updated recommendations for the use of HUD, including nomenclature, appropriateness, indications, operators, clinical environments, data management and storage, educational needs, and training of potential users. It also addresses gaps in evidence, controversial issues, and future technological developments.

Point-of-care echocardiographic screening for left-sided valve heart disease: high yield and affordable cost in an elderly cohort recruited in primary practice

Background

Data about the epidemiology of valvular heart disease (VHD) in the elderly is scarce. Hand-held ultrasound devices (HUDs) enable point-of-care ultrasound scanning (POCUS) but their use in an elderly population has not been reported for VHD screening in primary practice.

Methods

One hundred consecutive subjects aged >70 years without a VHD diagnosis had 2D and colour Doppler POCUS by an accredited sonographer, using a contemporary HUD (Vscan), in a primary practice setting. Patients with left-sided valve pathology identified by Vscan were referred for formal echo in the local tertiary cardiac centre.

Results

Mean age (s.d.) was 79.08 (3.74) years (72-92 years); 61 female. By Vscan, we found five patients with ≥moderate aortic stenosis (AS), eight with ≥moderate mitral regurgitation (MR) and none with ≥moderate aortic regurgitation. In the AS and MR groups each, one patient had valve intervention following from the initial diagnosis by Vscan, two and one respectively are under follow-up in the valve clinic, while two and four respectively refused TTE or follow-up. Two patients with moderate MR by Vscan had mild and mild/moderate MR respectively by TTE and were discharged. Total cost for scanning 100 patients was $18,201 - i.e. $182/patient.

Conclusions

Screening with a hand-held scanner (Vscan), we identified 5/100 elderly subjects who needed valve replacement or follow-up in valve clinic, at a cost of $182/patient. These findings have potential significance for the allocation of resources in the context of an ageing population.

Shape transitions between and within Zr isotopes

The Zirconium isotopes across the N=56,58 neutron sub­shell closures have been of special interest since years, sparked by the near doubly-magic features of 96Zr and the subsequent rapid onset of collectivity with a deformed ground-state structure already in 100Zr. Recent state-of-the-art shell model approaches did not only correctly describe this shape-phase transition in the Zr isotopic chain, but alsothe coexistence of non-collective structures and pronounced collectivity especially in 96,98Zr. Theisotope 98Zr is located on the transition from spherical to deformed ground state structures. We summarize recent experimental work to obtain the B(E2) excitation strengths of the first 2+ state of98Zr, including a new experiment employing the recoil-distance Doppler-shift method following a two-neutron transfer reaction.

A systematic review of pocket-sized imaging devices: small and mighty?

Introduction

Hand-held imaging devices are widely used in clinical practice and are a useful tool. There is no published review examining the diagnostic parameters achieved with these devices in clinical practice.

Methods

We searched three online medical literature databases (PubMed, EMBASE and MEDLINE) for all literature published up until January 2018. We selected studies that (1) were conducted in the adult population; (2) used a truly hand-held device; (3) featured sensitivities and/or specificities on the use of the hand-held scanner. We extracted and summarised the diagnostic metrics from the literature.

Results

Twenty-seven articles were excluded from the initial 56 relevant articles, as the device featured was not truly hand-held. Ultimately a total of 25 studies were analysed. Sixteen studies were carried out by experienced users, seven by users with little previous experience and two studies by nurses. High diagnostic parameters were achieved by all three groups when scanning cardiac pathology and intra-abdominal structures. Training of non-expert users varied, taking a mean of 21.6 h. These hand-held devices can change diagnoses at the bedside and be used as gate-keepers to formal echocardiography. Individual studies show them to be cost-effective.

Conclusion

Hand-held echocardiography is a useful tool in the hands of experts and novices alike. Studies conducted are highly heterogeneous making it difficult to pool data for the diagnostic metrics. Further studies with rigorous methodology are needed to evaluate the true diagnostic potential in the hands of non-experts and in the community as well as to validate training protocols.

Systematic Study of Ferromagnetism in CrxSb2-xTe3 Topological Insulator Thin Films using Electrical and Optical Techniques

Ferromagnetic ordering in a topological insulator can break time-reversal symmetry, realizing dissipationless electronic states in the absence of a magnetic field. The control of the magnetic state is of great importance for future device applications. We provide a detailed systematic study of the magnetic state in highly doped Cr_xSb_2−xTe₃ thin films using electrical transport, magneto-optic Kerr effect measurements and terahertz time domain spectroscopy, and also report an efficient electric gating of ferromagnetic order using the electrolyte ionic liquid [DEME][TFSI]. Upon increasing the Cr concentration from x = 0.15 to 0.76, the Curie temperature (T_c) was observed to increase by ~5 times to 176 K. In addition, it was possible to modify the magnetic moment by up to 50% with a gate bias variation of just ±3 V, which corresponds to an increase in carrier density by 50%. Further analysis on a sample with x = 0.76 exhibits a clear insulator-metal transition at T_c, indicating the consistency between the electrical and optical measurements. The direct correlation obtained between the carrier density and ferromagnetism - in both electrostatic and chemical doping - using optical and electrical means strongly suggests a carrier-mediated Ruderman-Kittel-Kasuya-Yoshida (RKKY) coupling scenario. Our low-voltage means of manipulating ferromagnetism, and consistency in optical and electrical measurements provides a way to realize exotic quantum states for spintronic and low energy magneto-electronic device applications.

Hand-held ultrasonography: An opportunity for "hands-on" teaching of medicine

This article was migrated. The article was marked as recommended. Background: As ultrasound offers students an opportunity to study anatomy, physiology and pathophysiology actively, we used hand-held ultrasound (HHU) devices to augment current teaching of cardiac murmurs and pathology. Methods: Three types of teaching sessions (of different duration) were explored: 1) compulsory teaching on cardiac murmurs (n=40); 2) extra-curricular teaching of cardiac murmurs (n=8); 3) extra-curricular ultrasound course (n=6). We assessed students' ability to identify valvular lesions on auscultation, and anatomy and pathology on echocardiography, and sought qualitative feedback. Results: Using echocardiography to teach murmurs improved murmur recognition by auscultation alone from 23% pre-test to 93% post-test (p=0.017). Students were able to identify major cardiac anatomical landmarks on echo images (57% vs 98% ( p=0.027) in the voluntary teaching session lasting 90 minutes, and 40% vs 82% ( p=0.027) after the 3 week cardiac ultrasound course. The mean accuracy for diagnosing cardiac pathology on a printed image alone after the 3 week ultrasound course was 71%. Students unanimously found the sessions useful and engaging, and reported they would like further teaching about using ultrasound. Conclusion: Medical students found the sessions engaging, enjoyed this novel way of teaching and would like further teaching using ultrasound. Using hand-held ultrasound scanners to augment the teaching of cardiac murmurs to medical students is feasible and effective.

Paramagnetism in Bacillus spores: Opportunities for novel biotechnological applications

Spores of Bacillus megaterium, Bacillus cereus, and Bacillus subtilis were found to exhibit intrinsic paramagnetic properties as a result of the accumulation of manganese ions. All three Bacillus species displayed strong yet distinctive magnetic properties arising from differences in manganese quantity and valency. Manganese ions were found to accumulate both within the spore core as well as being associated with the surface of the spore. Bacillus megaterium spores accumulated up to 1 wt.% manganese (II) within, with a further 0.6 wt.% adsorbed onto the surface. At room temperature, Bacillus spores possess average magnetic susceptibilities in the range of 10-6 to 10-5 . Three spore-related biotechnological applications-magnetic sensing, magnetic separation and metal ion adsorption-were assessed subsequently, with the latter two considered as having the most potential for development.

Hand-held Ultrasound Scanners in Medical Education: A Systematic Review

Background

Ultrasound imaging devices are becoming popular in clinical and teaching settings, but there is no systematic information on their use in medical education. We conducted a systematic review of hand-held ultrasound (HHU) devices in undergraduate medical education to delineate their role, significance, and limitations.

Methods

We searched Cochrane, PubMed, Embase, and Medline using the strategy: [(Hand-held OR Portable OR Pocket OR "Point of Care Systems") AND Ultrasound] AND (Education OR Training OR Undergraduate OR "Medical Students" OR "Medical School"). We retained 12 articles focusing on undergraduate medical education. We summarised the patterns of HHU use, pooled and estimated sensitivity, and specificity of HHU for detection of left ventricular dysfunction.

Results

Features reported were heterogeneous: training time (1-25 hours), number of students involved (1-an entire cohort), number of subjects scanned (27-211), and type of learning (self-directed vs. traditional lectures + hands-on sessions). Most studies reported cardiac HHU examinations, but other anatomical areas were examined, e.g. abdomen and thyroid. Pooled sensitivity 0.88 [95% confidence interval (CI) 0.83-0.92] and specificity 0.86 (95% CI 0.81-0.90) were high for the detection of left ventricular systolic dysfunction by students.

Conclusion

Data on HHU devices in medical education are scarce and incomplete, but following training students can achieve high diagnostic accuracy, albeit in a limited number of (mainly cardiac) pathologies. There is no consensus on protocols best-suited to the educational needs of medical students, nor data on long-term impact, decay in proficiency or on the financial implications of deploying HHU in this setting.