Procedia Technology最新文献

A simple impedimetric label-free immunosensor was developed for the specific and sensitive detection of mucin 4 (MUC 4) protein by using graphite based screen printed electrodes modified with an aryl diazonium salt or compound (p- aminophenylacetic acid) for the immobilization of antibody anti-MUC4 via amidic bond. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used in order to characterize and optimize the electrografting process. The parameters involved in each step of the immunosensor design were optimized. The performance of the immunoassay in terms of sensitivity, reproducibility and selectivity was studied.

Early and reliable diagnostic of cancer is mandatory to increase patient survival, thus requiring efficient and reliable analytical methods for such a purpose. Within this context, different strategies implying the development of electrochemical biosensors for the sensitive, selective and rapid multiplexed biosensing of genetic or protein cancer-related biomarkers are addressed in this presentation. In particular, novel sensing platforms have been developed for the determination of miRs, interleukin (IL)-8 mRNA, IL-8 protein, and cancer specific receptors. The developed methodologies allow for the determination of the target analytes at clinically relevant levels in complex samples: cancer cells, human tissues cell lysates, serum and raw saliva and can be easily extended to the determination of other relevant biomarkers.

In biological fluids, proteins and other biomolecules bind to the surface of nanoparticles to form a coating known as the protein corona which in turn becomes primary determinant of the nanoparticles’ fate and behaviour. Here we develop a QCM-based platform and methodology to obtain data from real-time interactions of nanoparticles with selected human plasma proteins. Polystyrene particles coated with transferrin are immobilized on QCM sensor chips and by means of a ‘sandwich’ format binding assay, specific epitopes on the particles can be quantified as measured by the increase of the sensor's resonant frequency. Cell binding experiments where adherent cells are directly grown on the sensor surface are also performed. Interaction of nanoparticles injected over the cell surface is observed only in the case of particle-transferrin complexes demonstrating that it is the nanoparticle-corona complex, rather than the native nanoparticle, “what the cell sees”, with the corona being the interface between the nanoparticle and the cellular system. Our data highlight the potential of the proposed QCM-based platform and methodology for characterization of the bio-nano-interface and tracking the interaction of nanoparticles with biological cells in the presence of a realistic milieu.

Here we propose a straightforward method to functionalize gold nanostructures by using an appropriate peptide sequence already selected toward gold surfaces and derivatized with another sequence for the capture of a molecular target. Large scale 3D-plasmonic devices with different nanostructures were fabricated by means of direct nanoimprint technique. The present work is aimed to address different innovative aspects related to the fabrication of large-area 3D plasmonic arrays, their direct and easy functionalization with capture elements, and their spectroscopic verifications through enhanced Raman and enhanced fluorescence techniques.

Bacterial infection is a disaster leading to high fatal rate in intensive caring unit. Rapid profiling of infectious bacteria is necessary for applying the correct medication. Current gold standard using plate inoculation is inaccurate, time-consuming and labour-intensive. Therefore we have developed a molecular diagnostic approach to target marker DNA of the infectious bacteria for rapid profiling. A micro-fluidic platform lab-on-a-disc (LOAD) has been adopted because using one simple spinning action can provide highly controllable centrifugation drive force for the actuation of samples and reagents anywhere within the boundary of the disc. When centrifugal force-triggered valve is applied, complex sequential flow of liquid can be controlled with various centrifugal force. This will enable parallel execution of many reactions simultaneously with minimal complexity in the design of fluidic pumping and flow control.

We report an integrated LOAD for direct sample-to-answer applications - fully automated assay from patient's sample input to detection of signal output. The integrated LOAD with PDMS-made microfludic disc performs three major functions, namely DNA extraction, LAMP reaction and detection. Using microfluidics technology, target bacteria can be detected using as little as 10 μL blood sample loaded into sample loading site. The DNA release after cell lysis in heating site is bound on the silica membrane. After washing, the purified DNA elution is subjected to LAMP reaction to amplify the target genetic sequence. Loop-mediated isothermal amplification (LAMP) is an isothermal nucleic acid amplification method where reaction occurs under 65 ^oC. The amplified signal is reported by DNA binding fluorescent dye. Our prototype shows high yield and purity of bacterial DNA from clinical samples such as blood. We demonstrated the detection of Acinetobacter baumanii, which is one of the key pathogens resulting in hospital-acquired infections, in clinical blood sample using the LOAD platform. Fast signal detection and active temperature control within the LOAD platform has also enabled real-time LAMP targeting of specific DNA sequences as barcodes to identify infected bacterial species. We found the detection sensitivity of LAMP using DNA is 10^-15 g, while that of bacteria concentration is 10² cfu/ml. The system is capable of providing bacterial DNA profiling within 2 hours.

In conclusion, our integrated LOAD is a simple (sample-to-answer), specific (specific genetic sequences recognition), robust (automated assay on microfluidic disc) method for rapid molecular diagnosis of bacterial infection. The short turnaround time and the technical advancement of sample-to-answer in one LOAD platform approach for rapid bacterial detection should have much potential in addressing the needs of point-of-care medical diagnosis applications. The simplicity allows the clinical healthcare workers to utilize