Submit to Biosensors Review for Biosensors

Journal Menu

Journal Browser

► Journal Browser

Biosensors, Volume 14, Issue 9 (September 2024) – 5 articles

Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
You may sign up for e-mail alerts to receive table of contents of newly released issues.
PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.

Order results

Result details

Section

Show export options Show export options

Select all

Export citation of selected articles as:

15 pages, 2013 KiB

Open AccessArticle

Enhancing Heavy Metal Detection through Electrochemical Polishing of Carbon Electrodes

by Sanjeev Billa, Rohit Boddu, Shabnam Siddiqui and Prabhu U. Arumugam

Biosensors 2024, 14(9), 412; https://doi.org/10.3390/bios14090412 (registering DOI) - 24 Aug 2024

Abstract

Our research addresses the pressing need for environmental sensors capable of large-scale, on-site detection of a wide array of heavy metals with highly accurate sensor metrics. We present a novel approach using electrochemically polished (ECP) carbon screen-printed electrodes (cSPEs) for high-sensitivity detection of cadmium and lead. By applying a range of techniques, including scanning electron microscopy, energy-dispersive spectroscopy, Raman spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry, we investigated the impact of the electrochemical potential scan range, scan rate, and the number of cycles on electrode response and its ability to detect cadmium and lead. Our findings reveal a 41 ± 1.2% increase in voltammogram currents and a 51 ± 1.6% decrease in potential separations (n = 3), indicating a significantly improved active electrode area and kinetics. The impedance model elucidates the microstructural and electrochemical property changes in the ECP-treated electrodes, showing an 88 ± 2% (n = 3) decrease in the charge transfer resistance, leading to enhanced electrode electrical conductivity. A bismuth-reduced graphene oxide nanocomposite-modified, ECP-treated electrode demonstrated a higher cadmium and lead sensitivity of up to 5 ± 0.1 μAppb⁻¹cm⁻² and 2.7 ± 0.1 μAppb⁻¹cm⁻² (n = 3), respectively, resulting in sub-ppb limits of detection in spiked deionized water samples. Our study underscores the potential of optimally ECP-activated electrodes as a foundation for designing ultrasensitive heavy metal sensors for a wide range of real-world heavy metal-contaminated waters. Full article

(This article belongs to the Special Issue Applications of Advanced Electrochemical (Bio)sensors in Environment, Food, and Medicine)

10 pages, 1732 KiB

Open AccessArticle

Core–Shell PEDOT-PVDF Nanofiber-Based Ammonia Gas Sensor with Robust Humidity Resistance

by Shenghao Xiao, Mengjie Hu, Yinhui Hong, Mengjia Hu, Tongtong Sun and Dajing Chen

Biosensors 2024, 14(9), 411; https://doi.org/10.3390/bios14090411 (registering DOI) - 24 Aug 2024

Abstract

Current ammonia sensors exhibit cross-sensitivity to water vapor, leading to false alarms. We developed a core–shell nanofiber (CSNF) structure to address these issues, using conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as the core and hydrophobic polyvinylidene fluoride-tetrafluoroethylene (PVDF-TrFE) as the shell. The PEDOT-PVDF CSNF, with a diameter of ~500 nm and a 300 nm thick PVDF layer, showed a superior sensitivity and humidity resistance compared to conventional PEDOT membranes for ammonia concentrations of 10–100 ppm. In humid environments, CSNF sensors outperformed membrane sensors, exhibiting a tenfold increase in performance at 51% relative humidity (RH). This study highlights the potential of CSNF sensors for practical ammonia detection, maintaining a high performance under varying humidity levels. Full article

(This article belongs to the Section Nano- and Micro-Technologies in Biosensors)

16 pages, 6079 KiB

Open AccessArticle

A Finger-Actuated Sample-Dosing Capillary-Driven Microfluidic Device for Loop-Mediated Isothermal Amplification

by Xuan Le, Jianxiong Chan, James McMahon, Jessica A. Wisniewski, Anna Coldham, Tuncay Alan and Patrick Kwan

Biosensors 2024, 14(9), 410; https://doi.org/10.3390/bios14090410 - 23 Aug 2024

Viewed by 252

Abstract

Loop-mediated isothermal amplification (LAMP) has attracted significant attention for rapid and accurate point-of-care diagnostics. However, integrating sample introduction, lysis, amplification, and detection steps into an easy-to-use, disposable system has so far been challenging. This has limited the uptake of the technique in practical applications. In this study, we developed a colourimetric one-step LAMP assay that combines thermolysis and LAMP reaction, to detect the SARS-CoV-2 virus in nasopharyngeal swab samples from COVID-19-infected individuals. The limit of detection was 500 copies per reaction at 65 °C for 25 min in reaction tubes. Additionally, we developed a finger-operated capillary-driven microfluidic device with selective PVA coating. This finger-actuated microfluidic device could self-dose the required sample amount for the LAMP reaction and inhibit sample evaporation. Finally, we integrated the LAMP assay into the microfluidic device by short-term pre-storage of the LAMP master mix. Using this device, nasopharyngeal swab samples from COVID-19-infected individuals showed positive results at a reaction time of 35 min at 65 °C. This integrated device may be adapted to detect other RNA viruses of interest rapidly. Full article

(This article belongs to the Special Issue Biosensors Based on Isothermal Nucleic Acid Amplification Strategies)

► Show Figures

Figure 1

19 pages, 3634 KiB

Open AccessArticle

Polarized and Evanescent Guided Wave Surface-Enhanced Raman Spectroscopy of Ligand Interactions on a Plasmonic Nanoparticle Optical Chemical Bench

by Xining Chen and Mark P. Andrews

Biosensors 2024, 14(9), 409; https://doi.org/10.3390/bios14090409 - 23 Aug 2024

Viewed by 186

Abstract

This study examined applications of polarized evanescent guided wave surface-enhanced Raman spectroscopy to determine the binding and orientation of small molecules and ligand-modified nanoparticles, and the relevance of this technique to lab-on-a-chip, surface plasmon polariton and other types of field enhancement techniques relevant to Raman biosensing. A simplified tutorial on guided-wave Raman spectroscopy is provided that introduces the notion of plasmonic nanoparticle field enhancements to magnify the otherwise weak TE- and TM-polarized evanescent fields for Raman scattering on a simple plasmonic nanoparticle slab waveguide substrate. The waveguide construct is called an optical chemical bench (OCB) to emphasize its adaptability to different kinds of surface chemistries that can be envisaged to prepare optical biosensors. The OCB forms a complete spectroscopy platform when integrated into a custom-built Raman spectrograph. Plasmonic enhancement of the evanescent field is achieved by attaching porous carpets of Au@Ag core shell nanoparticles to the surface of a multi-mode glass waveguide substrate. We calibrated the OCB by establishing the dependence of SER spectra of adsorbed 4-mercaptopyridine and 4-aminobenzoic acid on the TE/TM polarization state of the evanescent field. We contrasted the OCB construct with more elaborate photonic chip devices that also benefit from enhanced evanescent fields, but without the use of plasmonics. We assemble hierarchies of matter to show that the OCB can resolve the binding of Fe²⁺ ions from water at the nanoscale interface of the OCB by following the changes in the SER spectra of 4MPy as it coordinates the cation. A brief introduction to magnetoplasmonics sets the stage for a study that resolves the 4ABA ligand interface between guest magnetite nanoparticles adsorbed onto host plasmonic Au@Ag nanoparticles bound to the OCB. In some cases, the evanescent wave TM polarization was strongly attenuated, most likely due to damping by inertial charge carriers that favor optical loss for this polarization state in the presence of dense assemblies of plasmonic nanoparticles. The OCB offers an approach that provides vibrational and orientational information for (bio)sensing at interfaces that may supplement the information content of evanescent wave methods that rely on perturbations in the refractive index in the region of the evanescent wave. Full article

(This article belongs to the Special Issue SERS-Based Biosensors: Design and Biomedical Applications)

► Show Figures

Figure 1

14 pages, 5172 KiB

Open AccessArticle

Fabrication of Patterned Magnetic Particles in Microchannels and Their Application in Micromixers

by Tianhao Li, Chen Yang, Zihao Shao, Ya Chen, Jiahui Zheng, Jun Yang and Ning Hu

Biosensors 2024, 14(9), 408; https://doi.org/10.3390/bios14090408 - 23 Aug 2024

Viewed by 181

Abstract

Due to the extremely low Reynolds number, the mixing of substances in laminar flow within microfluidic channels primarily relies on slow intermolecular diffusion, whereas various rapid reaction and detection requirements in lab-on-a-chip applications often necessitate the efficient mixing of fluids within short distances. This paper presents a magnetic pillar-shaped particle fabrication device capable of producing particles with planar shapes, which are then utilized to achieve the rapid mixing of multiple fluids within microchannels. During the particle fabrication process, a degassed PDMS chip provides self-priming capabilities, drawing in a UV-curable adhesive-containing magnetic powder and distributing it into distinct microwell structures. Subsequently, an external magnetic field is applied, and the chip is exposed to UV light, enabling the mass production of particles with specific magnetic properties through photo-curing. Without the need for external pumping, this chip-based device can fabricate hundreds of magnetic particles in less than 10 min. In contrast to most particle fabrication methods, the degassed PDMS approach enables self-priming and precise dispensing, allowing for precise control over particle shape and size. The fabricated dual-layer magnetic particles, featuring fan-shaped blades and disk-like structures, are placed within micromixing channels. By manipulating the magnetic field, the particles are driven into motion, altering the flow patterns to achieve fluid mixing. Under conditions where the Reynolds number in the chip ranges from 0.1 to 0.9, the mixing index for substances in aqueous solutions exceeds 0.9. In addition, experimental analyses of mixing efficiency for fluids with different viscosities, including 25 wt% and 50 wt% glycerol, reveal mixing indices exceeding 0.85, demonstrating the broad applicability of micromixers based on the rapid rotation of magnetic particles. Full article

(This article belongs to the Special Issue Design, Fabrication, and Applications of Microfluidic Devices for Biosensing)

► Show Figures