Procedia Technology最新文献

Resistive pulse sensors, RPS, are allowing the transport mechanism of molecules, proteins and even nanoparticles to be characterized as they traverse small channels. Here we present our recent advancement of the technique identifying key experimental designs for potential POC assays. The first assay utilized superparamagnetic beads, if the surfaces of the beads are modified with an aptamer, the frequency of beads (translocations/minute) through the pore can be related to the concentration of specific proteins in the solution. Herein, we have demonstrated the successful use of TRPS to observe the binding of two proteins, to their specific aptamers simultaneously. We then adapt the measurement strategy and demonstrate that the translocation times of particles can be used to infer the zeta potential to measure the change in zeta potential of DNA modified particles. By measuring the translocation times of DNA modified nanoparticles as a function of packing density, length, structure, and hybridisation time, we observe a clear difference in zeta potential using both mean values, and population distributions as a function of the DNA structure. Finally we present the first comparison between assays that use resistive pulses or rectification ratios on a tunable pore platform.

The current trend towards flexible and light-weight portable electronic devices has raised the profile of the emerging field of printed electronics. Printable organic electronic devices provide a high-throughput and cost-effective approach for the fabrication of distributed healthcare devices, which will meet new market needs. Here, we present an innovative modular approach for the design and fabrication of printable biosensors. A “LEGO” style approach comprising various colloidal building blocks, such as conducting polymer-based microparticles and biopolymer-based microparticles (e.g. enzymes and antibodies) with well-defined and tunable nano-scale morphology, electrochemical behaviours and catalytic functions, were fabricated for the development of printable biosensors. Assembly of the printable biosensors can be performed simply by mixing various microparticles delivering the desired conductivity, capacitance, catalytic and affinity functions, followed by solvent-free printing of the microparticle mixture onto a substrate. The conductivity, capacitance and signal response of the printable biosensors were characterised. This modular approach allows high flexibility for the design for biosensors, as well as better integration between conducting polymers and biomolecules for the development of biosensors. As a proof-of-concept, a mediated glucose biosensor based on printable microparticles was developed and showed a high sensitivity of 2 mA (M cm²)^-1.

This work focuses on the development of optical sensors based on the LSPR phenomenon in nano-structured gold films suitable for detection of mycotoxins. A simple technology of annealing thin gold films was utilized for the formation of gold nano-islands exhibiting the LSPR effect. The morphology of gold nano-structures produced was studied with SEM and AFM while their optical properties were analysed with UV-vis absorption spectroscopy and spectroscopic ellipsometry (SE). A blue spectral shift of LSPR band caused by changes in the refractive index of medium constitutes the main principle of LSPR sensing. Bio-sensing tests were attempted using SE in total internal reflection mode (TIRE); a noticeable spectral shift was recorded on course of immune binding of aflatoxin B1 to specific antibodies immobilized on the surface of gold.

In this study, a MEMS-based microfluidic device combining DEP-based cell manipulation with size-based filtration for the enrichment of CTCs from blood with high-throughput was developed. Positive-DEP (pDEP) force and the hydrodynamic force have been used to fine-tune the cell movement over the planar electrodes (sliding) at a high flow rate (30 μl/min). While smaller sized RBCs passed through the gaps and were directed to the waste channels, cancer cells (K562 cells) were filtered and directed to the cancer cell outlet. A cell enrichment factor and depletion rate of RBCs were calculated as 1.45 and 60%, respectively.

In this communication we report the synthesis, characterization and applications of TeNTs decorated with PtNPs readily prepared by two simple steps to make a GC modified electrode suitable to be used as anode/cathode in fuel cells. In the 1^th step the large scale of Te nanotubes synthesis was obtained via a vapor deposition method; then in the 2^nd step TeNTs dispersed in methanol react with PtCl₂ to make TeNTs/PtNPs. Modified electrodes TeNTs/PtNPs/GC were then made by casting 20 μL of TeNTs/PtNPs/ethanol suspension onto GC surface and left to evaporate at room temperature. The as synthesized hybrid nanostructures, fully characterized by XRD, TEM and XPS analysis, were composed of Te nanotubes decorated with Pt nanoparticles. The electrochemical characterization of TeNTs/PtNPs composite material, performed by cyclic voltammetry (CV), showed exceptional electrocatalytic activity towards methanol oxidations and oxygen reduction.

Recently, the possibility of developing surface-enhanced Raman scattering (SERS)-based biosensors for rapid detection of bacteria is widely explored. With this purpose, we used SERS spectroscopy along with chemometric techniques to detect and identify by their spectral profiles relevant pathogens grown in different cultivation conditions by using in situ synthesized silver colloid (Bacteria@AgNPs) and incubation in silver colloid [1], [2]. Enhanced darkfield hyperspectral microscopy analysis was employed for characterizing the interaction between the bacteria and silver nanoparticles (Bacteria@AgNPs system). Moreover, a label-free SERS-based protocol was optimized and the influence of taxonomic affiliation and time-dependent effects of incubation in silver colloid were monitored.

By using SERS-based protocol with the optimized experimental parameters, the label-free detection and identification of the most common pathogens (E. coli, Aeromonas, M. morganii, E. lactis, L. casei and L. monocytogenes) was assessed. The reduced sample volume required, the rapid spectral acquisition (within 5 minutes), and the use of chemometric techniques for an unbiased analysis of the SERS single-cell spectra, provided the optimum platform for developing SERS-based biosensors for food safety, water research, or health care real-life applications.

The first amperometric immunosensor for the quantification of TGF–β1 is described in this work. The immunosensor design involves disposable devices using carboxylic acid–functionalized magnetic microparticles supported onto screen–printed carbon electrodes and covalent immobilization of the specific antibody for TGF–β1 using Mix&Go^TM polymer. A sandwich–type immunoassay was performed using peroxidase–labeled streptavidin (Poly–HRP–Strept) polymer for signal amplification. The calibration plot allowed a range of linearity extending between 15 and 3000 pg/mL TGF–β1 (LOD 10 pg/mL). The usefulness of the immunosensor was evaluated by analyzing spiked urine at different pg/mL concentration levels.

Herein, we report a scalable synthesis of multifunctional conducting polyacrylic acid (PAA) hydrogel (MFH) integrated with reduced grapheme oxide (rGO), vinyl substituted polyaniline (VS-PANI) and lutetium phthalocyanine (LuPc₂) as three dimensional robust matrix for glucose oxidase (GOx) immobilization (PAA-rGO/VS-PANI/LuPc₂/GOx-MFH). We have integrated the multicomponents such as PAA with rGO, VS-PANI through free radical polymerization using methylene bis-acrylamide, ammonium persulphate as the cross linker and initiator. The LuPc₂ was then doped to form multifunctional hydrogel (PAA-rGO/VS-PANI/LuPc₂-MFH). Finally, biosensor was fabricated by immobilizing GOx into PAA-rGO/VS-PANI/LuPc₂-MFH and subsequently used for electrochemical detection of glucose.

Ocular fluid is an extracellular fluid excreted from the tear gland. Several important markers from ocular fluid have been identified as having significant clinical diagnostic value for various diseases. The contact lens is disposable, relatively cheap and serves as a platform to obtain direct intimate contact with ocular fluid and is therefore an attractive and a promising platform for point-of-care diagnostic tests. Here, we present an entirely new concept of a wearable theranostic device, in the form of a contact lens (theranostic lens) with a dual-function hybrid surface, to modulate and detect a pathogenic attack by herpes simplex virus type 1 (HSV-1). The theranostic lenses were constructed using a Layer-by-Layer (LbL) surface engineering technique to produce a functional hybrid surface containing both an anti-HSV-1 polysulfonate compound and specific antibodies for viral detection. The resulting theranostic lenses retained good optically transparency and surface wettability, and were non-toxic towards human corneal epithelial cells (HCECs). We showed that the theranostic lenses could capture and concentrate interleukin-1α (IL-1α), which is upregulated during HSV-1 infection, using an artificial cornea model integrated with a microfluidic system mimicking tear flow. The theranostics lenses exhibited effective anti-HSV-1 activity and good analytical performance for the detection of IL-1α, with a limit of detection of 1.43 pg mL^-1 and a wide linear range covering the clinically relevant region. Our strategy also tackles the major problems in tear diagnostics that are associated with the small volumes from tear sampling and the low concentration of biomarkers in these samples. This work offers a new paradigm for wearable, non-invasive healthcare devices combining diagnosis and protection against disease. We believe that this approach holds promise as a next-generation, point-of-care and de-centralized diagnostic/theranostic platform for a range of biomarkers.

This study examines the principles and milestones of nanoparticle (NP)-based colorimetric sensors and probes developed by our research group. A novel method for antioxidant capacity estimation was developed on the polyphenol-mediated growth of Ag-NPs and optical monitoring of the corresponding plasmon absorption bands. A new optical sensor using Ellman's reagent-adsorbed gold nanoparticles in colloidal solution was devised to selectively determine biothiols. Nitrite was determined by means of 4-aminothiophenol-modified Au-NPs and naphthylethylene diamine as coupling agent. Hydrogen peroxide was detected with the use of Fe₃O₄ magnetite NPs as peroxidase-like catalyst using a N,N-dimethyl-p-phenylenediamine (DMPD) probe.