Visible-light-driven dynamic cancer therapy and imaging using graphitic carbon nitride nanoparticles.

Organic graphitic carbon nitride nanoparticles (NP-g-CN), less than 30 nm in size, were synthesized and evaluated for photodynamic therapy (PDT) and cell imaging applications. NP-g-CN particles were prepared through an intercalation process using a rod-like melamine-cyanuric acid adduct (MCA) as the molecular precursor and a eutectic mixture of LiCl-KCl (45:55 wt%) as the reaction medium for polycondensation. The nano-dimensional NP-g-CN penetrated the malignant tumor cells with minimal hindrance and effectively generated reactive oxygen species (ROS) under visible light irradiation, which could ablate cancer cells. When excited by visible light irradiation (λ > 420 nm), NP-g-CN introduced to HeLa and cos-7 cells generated a significant amount of ROS and killed the cancerous cells selectively. The cytotoxicity of NP-g-CN was manipulated by altering the light irradiation and the BP-g-CN caused more damage to the cancer cells than normal cells at low concentrations. As a potential non-toxic organic nanomaterial, the synthesized NP-g-CN are biocompatible with less cytotoxicity than toxic inorganic materials. The combined effects of the high efficacy of ROS generation under visible light irradiation, low toxicity, and bio-compatibility highlight the potential of NP-g-CN for PDT and imaging without further modification.

A fluorescent sensor for selective detection of cyanide using mesoporous graphitic carbon(IV) nitride.

A turn-on fluorescence sensor, Cu(2+)-c-mpg-C(3)N(4), was developed for detection of CN(-) in aqueous solution by simply mixing cubic mesoporous graphitic carbon nitride (c-mpg-C(3)N(4)) and aqueous solution of Cu(NO(3))(2). The highly sensitive detection of CN(-) with a detection limit of 80 nM is not only possible in aqueous solution but also in human blood serum.

Advanced cleanup process of the free-flow microfluidic device for protein analysis.

The treatment of samples preparation is generally recognized as a bottleneck for the rapid analysis of protein because of the off-chip performance in many cases. In this study, we used the charge characteristics of protein to develop a simple and rapid electro-microfluidic desalting system as an effective means of cleaning up protein sample. When we loaded a urea-rich protein sample and a buffer solution into a free-flow zone electrophoresis (FFZE) chamber, the microfluidic device was able to separate the charged protein sample and the non-charged urea. With a 90 V electric field in the FFZE chamber, the removal efficiency of the urea was about 88% and the recovery of the protein was 78%. In addition, the desalted protein sample used in this device showed significant improvement with respect to the MALDI-TOF-MS spectrum signal of a fusion protein, which was fused to the gold-binding polypeptide with enhanced green fluorescent protein, as a model protein. The inflow of the purified fusion protein sample can be successfully immobilized on the gold surface and analyzed by confocal fluorescence microscopy and surface plasmon resonance for biotechnological sensors.

Development of a fully integrated microfluidic system for sensing infectious viral disease.

An active micromixer system utilizing the magnetic force was developed and examined for its ability to facilitate the mixing of more than two fluid flows. The mixing performance of the active micromixer was evaluated in aqueous-aqueous systems including dyes for visual observation. A complete analytical microfluidic system was developed by integrating various functional modules into a single chip, thus allowing cell lysis, sample preparation, purification of intracellular molecules, and subsequent analysis. Upon loading the cell samples and lysis solution into the mixing chamber, the integrated microfluidic device allows efficient cell disruption by rotation of a micromagnetic disk and control of mixing time using the Teflon-coated hydrophobic film as a microvalve. This inflow is followed by separating the cell debris and contaminated proteins from the cell lysate sample using the acrylamide (AAm)-functionalized SPE. The inflow of partially purified cell lysate sample containing the gold binding polypeptide (GBP)-fusion protein was bound onto the gold micropatterns by means of its metal binding affinity. The GBP-fusion method allows immobilization of proteins in bioactive forms onto the gold surface without surface modification suitable for studying antigen-antibody interaction. It was used for the detection of severe acute respiratory syndrome (SARS), an infectious viral disease, as an example case.

Removal of bovine serum albumin using solid-phase extraction with in-situ polymerized stationary phase in a microfluidic device.

Serum albumin, one of the most abundant serum proteins, blocks the expression of other important biomarkers. The objective of this study is to remove serum albumin effectively by using solid-phase extraction (SPE) in microfluidic devices. Photo-polymerized adsorbent as a stationary phase of SPE was used to remove bovine serum albumin (BSA). The adsorption capacity was examined with the effect of pH and concentration in BSA solution, and adjustment of monomer concentration such as hydrophilic 2-acrylamido-2-methyl-1-propanesulfonic acid and acrylamide in the adsorbent. The effect of hydrophobic butyl methacylate on BSA adsorption was also studied. Selective removal in a bicomponent with BSA and bovine gamma-globulin was performed by adjusting the pH as required.