An overview and future perspectives of user-friendly microfluidic devices have been reported in terms of practical sample preparation in point-of-care testing.
Montmorillonite is a multifunctional clay mineral and a major component of bentonite. Montmorillonite has been used in various industrial and pharmaceutical fields due to its unique characteristics, which include swelling and adsorption. The high adsorption capacity of montmorillonite contributes to increase drug entrapment and sustained-release of drugs. Montmorillonite generally sustains drug release in many formulations by strongly adsorbing to the drug. In addition, montmorillonite enhances the dissolution rate and bioavailability of hydrophobic drugs. Moreover, montmorillonite was applied to form composites with other polymer-based delivery systems. Thus, montmorillonite could be applied to formulate diverse drug delivery systems to control and/ or improve the pharmaceutical properties of drugs, including solubility, dissolution rate, and absorption. In this review, perspectives of applying montmorillonite as a pharmaceutical excipient in drug delivery systems are discussed.
This paper presents a pressed paper-based dipstick that enables detection of foodborne pathogens with multistep reactions by exploiting the delayed fluid flow and channel partition formation on nitrocellulose (NC) membrane. Fluid behaviors are easily modified by controlling the amount of pressure and the position of pressed region on the NC membrane. Detection region of the dipstick is optimized by controlling flow rate and delayed time based on Darcy's law. All the reagents required for assay are dried on the NC membrane and they are sequentially rehydrated at the prepartitioned regions when the device is dipped into sample solution. In this manner, multistep reactions can be facilitated by one-step dipping of the dipstick into the sample solution. As a proof of concept, we performed detection of two fatal foodborne pathogens (e.g., Escherichia coli O157:H7 and Salmonella typhimurium) with signal enhancement. In addition, we expanded the utilization of channel partitions by developing a pressed paper-based dipstick into dual detection format.
An amphiphilic hyaluronic acid-ceramide-dopamine (HACE-d) conjugate was prepared, and HACE-d-based nanoparticles (NPs) including phloretin (as an inhibitor of glucose transporter (GLUT1)) were fabricated. Mussel-inspired property of d was introduced to HACE NPs, and it may improve tumor targetability and penetration in addition to passive (based on enhanced permeability and retention effect) and active (interaction between HA and CD44 receptor) tumor targeting effects. HACE-d/phloretin NPs with 279 nm mean diameter, ∼0.2 polydispersity index, and -18 mV zeta potential were successfully fabricated, and a sustained drug release pattern was observed. HACE-d/phloretin NPs exhibited enhanced cellular accumulation efficiency and antiproliferation property, compared with HACE/phloretin NPs, in MDA-MB-231 cells (GLUT1 and CD44 receptor-expressed human breast adenocarcinoma cells). In a MDA-MB-231 spheroid model, HACE-d NPs group showed better tumor penetration efficiency and spheroid growth inhibitory effect rather than HACE NPs group. According to the optical imaging test in MDA-MB-231 tumor-xenografted mouse, HACE-d NPs group exhibited more selective distribution in tumor region and deeper infiltration into the inner part of tumor compared with HACE NPs group. After intravenous injection, HACE-d/phloretin NPs group also exhibited improved antitumor efficacies rather than the other experimental groups in MDA-MB-231 tumor-xenografted mouse. All these findings suggested that HACE-d/phloretin NP may be a promising tumor targetable and penetrable nanosystem for the therapy and imaging of GLUT1 and CD44 receptor-expressed cancers.
This paper reports a method to control the fluid flow in paper-based microfluidic devices simply by pressing over the channel surface of paper, thereby decreasing the pore size and permeability of a non-woven polypropylene sheet. As a result, fluid resistance is increased in the pressed region and causes flow rate to decrease. We characterize the decrease of flow rate with respect to different amounts of pressure applied, and up to 740% decrease in flow velocity was achieved. In addition, we demonstrate flow rate control in a Y-shaped merging paper and sequential delivery of multiple color dyes in a three-branched paper. Furthermore, sequential delivery of multiple fluid samples is performed to demonstrate its application in multi-step colorimetric immunoassay, which shows a 4.3-fold signal increase via enhancement step. V C 2014 AIP Publishing LLC.
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