Procedia Technology最新文献

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.

One important factor for developing biosensors is taking the source of electrical energy into account. The source of electricity is needed whenever we consider point-of-care diagnostics, in-vivo tests or in particular – environmental applications. The need of supplying energy to biosensor may be an important obstacle for its everyday use, particularly in developing countries. Here, we present the concept of biosensor able to generate power by bioelectrochemical oxidation of the analyte and thus – able to autonomously maintain its operation.

The development of highly sensitive and specific colorimetric biosensor for pathogens spot detection is currently researchers challenge. This study illustrates the design and development of specific peptide probe for the detection of specific proteases secreted from pathogens. These proteases precisely cleaved specific peptide substrate labeled with nano-magnetic beads and attached to gold sensing surface.

The superiority of this approach is based on its low-cost, simplicity being colorimetric, can be run by unskilled personnel and can be applied to real samples (without the need for isolation or purification) in short time (1-5 minute). Furthermore the test can be printed/fabricated on personal healthcare.

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.

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.

Rapid detection of infectious diseases has generated significant interest in recent years. The time consuming and costly conventional diagnostics methods substantiate the need to develop a cost-effective rapid infectious disease detection platform to address the persistently threatening health issues in developing countries. The recent advancements in nanotechnology and biosensing have manifested the potential to deliver an effective point-of-care diagnostics platform. In this work, the synthesis and fabrication of an ultrasensitive Copper doped Zinc oxide nanofiber based biosensing platform is reported. Copper doped Zinc oxide nanofibers are synthesized by simple electrospinning technique with fiber diameter of 100-200 nm. The structural and morphological characteristics of the nanofibres are studied using X-ray diffraction and field emission scanning electron microscopy. The label free detection of HRP2 protein with the Copper doped Zinc Oxide nanofiber has been investigated by Differential pulse voltammetric technique. Mercaptopropionic acid treatment of Copper doped Zinc oxide nanofiber generates carboxylic acid groups, which facilitate the covalent conjugation of Anti-HRP2. To the best of our knowledge, the fabricated immunosensor displays better sensitivity than the best malaria sensor reported in the literature based on different nanomaterials and different detection mechanism. The proposed platform exhibits very low limit of detection of 10 attogram per ml for the targeted HRP2 protein in a wide detection test range (ag/ml -μg/ml). The novel biosensor platform demonstrates good stability and selectivity which can be implemented for point-of-care diagnosis of biomarkers related to other infectious diseases.

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.