Biology subjects

Lau, M. P. H.

Publications and source records attributed to Lau, M. P. H..

5 recordsLinked to original sources

bioRxiv2022

A Low-Cost, 3D-Printed Biosensor for Rapid Detection of Escherichia coli

Detection of bacterial pathogens is significant in the fields of food safety, medicine, public health, etc. If bacterial pathogens are not treated promptly, antimicrobial resistance is possible and can lead to morbidity and mortality. Current bacterial detection methodologies rely on laboratory-based techniques that pose limitations such as long turnaround detection times, expensive costs, inadequate accuracy, and required trained specialists. Here, we describe a cost-effective and portable 3D-printed electrochemical biosensor that facilitates rapid detection of certain Escherichia coli (E. coli) strains (DH5, BL21, TOP10, and JM109) within 15 minutes using 500 L of sample and costs $2.50 per test. The sensor displayed an excellent limit of detection (LOD) of 53 cfu, limit of quantification (LOQ) of 270 cfu, and showed cross-reactivity with strains BL21 and JM109 due to shared epitopes. This advantageous diagnostic device is a potential candidate for high-frequency testing at point of care as well as applicable to various fields where pathogen detection is of interest.

bioengineering↗

bioRxiv2022

Identification of bacteria strains using the Recombinase Polymerase Amplification assay on a miniaturized solid-state pH sensor

Rapid identification of bacteria based on nucleic acid amplification allows dealing with the detection of pathogens in clinical, food, and environmental samples. Amplification product must be detected and analyzed by external devices or integrated complicated optical systems. Here, we developed a solid-state pH electrode based on iridium oxide (IrO2) films to measure released hydrogen ions (H+) from isothermal nucleic acid (NA) amplification of bacterial samples. By recombinase polymerase amplification (RPA), we achieved rapid (< 15 min) and sensitive (<30 copies) detection with an accuracy of about 0.03 pH. The RPA-based hydrogen ion sensing assay shows higher specificity, sensitivity, and efficiency as the same polymerase chain reaction (PCR) methods. We initially used the RPA-based sensor to detect E. coli species in laboratory samples. Among, 27 random laboratory samples of E. coli samples, 6 were found to be DH5alpha, 9 BL21, 3 HB101, 6 TOP10, and 3 JM109. The electrical detection of amplification provides generally applicable techniques for the detection of nucleic acid amplification, enabling molecular diagnostic tests in the field and integrating data transmission to the mobile device. These results can be future developed into an efficient tool for rapid on-site detection of bacterial pathogens in clinical samples.

bioengineering↗

bioRxiv2021

Simultaneous Cardiac and Neurological Monitoring to Assess Chemical Exposures and Drug Toxicity in Xenopus Laevis

Simultaneous monitoring of electrocardiogram (ECG) and electroencephalogram (EEG) under chemical exposure requires innovative engineering techniques that can capture minute physiological changes in studied animal models. However, this is often administered with a bulky system that may cause signal distortions and discomfort for animals. We develop an integrated bioelectronic sensing system to provide simultaneous ECG and EEG assessment in real-time under chemical exposure for Xenopus laevis. The microelectrode array (MEA) membrane with integrated ECG and EEG sensing offers an opportunity to achieve multichannel noninvasive electrophysiological monitoring with favorable dimensions and spatial resolution. To validate the performance of our system, we assessed the ECG and EEG of Xenopus under exposure of Pentylenetetrazol (PTZ), an epilepsy-inducing drug. Effects of PTZ were detected with clear ECG and EEG alterations, including frequent ictal and interictal EEG events, 30 dB average EEG amplitude elevations, abnormal ECG morphology, and heart rate changes. Overall, our Xenopus-based real-time electrophysiology monitoring system holds high potential for many applications in drug screening and remote environmental toxicity monitoring.

physiology↗

bioRxiv2021

Fetal Electrocardiogram Extraction from the Mother's Abdominal Signal Using the Ensemble Kalman Filter

Fetal electrocardiogram (fECG) assessment is essential throughout pregnancy to monitor the wellbeing and development of the fetus, and to possibly diagnose potential congenital heart defects. Due to the high noise incorporated in the abdominal ECG (aECG) signals, the extraction of fECG has been challenging. And it is even a lot more difficult for fECG extraction if only one channel of aECG is provided, i.e. in a compact patch device. In this paper, we propose a novel algorithm based on the Ensemble Kalman Filter (EnKF) for non-invasive fECG extraction from a single-channel aECG signal. To assess the performance of the proposed algorithm, we used our own clinical data, obtained from a pilot study with 10 subjects each of 20 min recording, and data from the PhysioNet 2013 Challenge bank with labeled QRS complex annotations. The proposed methodology shows the average positive predictive value (PPV) of 97.59%, sensitivity (SE) of 96.91%, and F1-score of 97.25% from the PhysioNet 2013 Challenge bank. Our results also indicate that the proposed algorithm is reliable and effective, and it outperforms the recently proposed Extended Kalman Filter (EKF) based algorithm.

bioengineering↗

bioRxiv2021

A Novel Art of Electrocardiogram Assessment in Zebrafish for Cardiovascular Disease Studies and Drug Screening

The zebrafish (Dario rerio) has proven to be an excellent animal model for biological research owing to its small size, low cost for maintenance, short generation time, amenable genetics, and optical transparency. Zebrafish have been extensively used in cardiovascular studies in which mutant lines with cardiovascular defects were introduced and analyzed. Despite the small size, technological advances have paved the way to effectively assess cardiac functions of zebrafish. Here, we present a novel art for long-term simultaneous monitoring and analysis of electrocardiogram (ECG) in multiple zebrafish with controlled environment. The system helps minimize the effect of anesthetic drug and temperature to cardiac rhythm side effects as well as save time and efforts by 40-50 fold compared with the conventional approach. We further employed the system to study the Na+ sensitivity in the development of sinus arrest in Tg(SCN5A-D1275N) fish, a study model of the sick sinus syndrome, as well as the relationship between this variant and drug administration. The novel ECG system developed in this study holds promise to greatly accelerate other cardiovascular studies and drug screening using zebrafish.

bioengineering↗