Procedia Technology最新文献

The functionalization of screen-printed electrodes (SPEs) with a thin film of reaction centre (RC) proteins from the phototrophic bacterium Rhodobacter (R.) sphaeroides, by means of laser induced forward transfer (LIFT) technique, allowed the fabrication of robust and sensitive bio-hybrid devices for terbutryn detection and analysis. The optimal wiring between RCs and the gold electrode surface, achieved by LIFT, led to the generation of cathodic photocurrents sustained by a direct electron transfer (DET) mechanism, which were attenuated by addition of the herbicide inhibitor.

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.

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.

This paper presents an LOC system combining microfluidic DEP channel with a CMOS image sensor for label and lens free detection and real-time counting of MCF-7 cells under continuous flow. Trapped and then released MCF-7 cells are accurately detected and counted under flow with a CMOS image sensor integrated underneath the DEP channel, for the first time in the literature. CMOS image sensor can capture 391 frames per second (fps) that allows detection of the released cells flowing through the channel with a flow rate up to 130 μl/min (0.468 m/s). Therefore, the proposed system is able to detect the cells under high flow where conventional techniques for cell quantification such as fluorescent tagging become unusable. Detected cells are automatically counted with a computer program and the counting accuracy of the whole system is 95%.

Already mass-produced stainless-steel pins offer the possibility of developing low-cost electroanalytical devices with a versatile disposition of the electrodes. Here we use these prefabricated pins as electrodes for enzymatic amperometric sensing. A conventional three-electrode configuration device is designed using two bare pins as reference and counter electrodes, and a carbon-coated pin as working electrode. Using a transparency sheet and standard connections as interface to conventional instrumentation, a pin-based sensor for glucose determination is developed. Finally, a multiplexed device with four pins acting as working electrodes, which can be useful for multiplexed immunosensing purposes, is designed.

Analytical Chemistry is nowadays one of the branches of Chemistry that has changed enormously due to the advances in technology and the trends it follows. Currently, the development of low-cost devices that are, at the same time, easy-to use and dispose, and produce fast and reliable responses is of eminent significance. Electrochemical biosensors fit perfectly with these requirements, as do paper-based devices. Here we present an enzymatic biosensor using a simple single-use paper-based device in which carbon ink is deposited in a hydrophilic area delimited by wax printing for acting as working electrode. Low-cost gold-plated connector headers are employed as reference and auxiliary electrodes as well as connections to the potentiostat. Glucose oxidase (GOx), horseradish peroxidase (HRP) and potassium ferrocyanide used as mediator of the electron transfer are adsorbed in the ink.

Introduction

Protein nanocages (PNCs) have been recognized as a promising platform for nanomedicine innovation. Real-time in vivo tracking of PNCs can provide critically important information for the development of PNC-based diagnostics and therapeutics. Here we demonstrate a strategy for monitoring the behaviors of PNCs in vivo by encapsulating a Ag₂S quantum dot (QD) with fluorescence in the second near-infrared window (NIR-II, 1000-1700 nm) inside the PNC, using a simian virus 40 (SV40) PNC (PNC_SV40) as a model.

Methods

The Ag₂S QD was encapsulated into the PNC_SV40 through controllable molecular self-assembly. The dynamic migration of Ag₂S@PNC_SV40 in living mouse was tracked in real time under an InGaAs-based shortwave infrared imaging system and was further corroborated by ex vivo imaging, inductively coupled plasma mass spectrometry analysis, and macrophage endocytosis assay.

Results

Benefitting from the high spatiotemporal resolution and deep tissue penetration of NIR-II fluorescence imaging, the dynamic distribution of the PNC_SV40 in living mice was tracked in real time with high fidelity, revealing rapid clearance from bloodstream within 5 min post-intravenous injection and selective accumulation in liver, spleen and bone marrow. Furthermore, adopting the PEGylation strategy, PEGylated PNC_SV40 presents remarkably different behaviors in vivo with significantly prolonged blood circulation and much less uptake in the reticuloendothelial system (RES), leading to desirable pharmacokinetics and pharmacodynamics of PNC-based nanomedicines.

Discussion

This study represents the first evidence of real-time tracking of the intrinsic behaviors of PNCs in vivo without interference in PNC-host interactions by encapsulating nanoprobes inside, instead of conjugating nanoprobes onto the outer surface of PNCs. The as-described imaging strategy will facilitate the study of interactions between exogenously introduced PNCs and host body, prompting the development of future protein-based drugs, high-efficacy targeted delivery system, sensors, etc.