The ability to photoregulate enzyme activities could provide important new opportunities for development of diagnostic assays, sequential bioprocessing, and lab assays in both traditional and microfluidic formats. We show here that the photoinduced changes in the size and hydration of a ''smart'' polymer chain coil can be used to regulate substrate access and enzyme activity when conjugated to the enzyme at a specific point just outside the active site. The photoresponsive polymers thus serve jointly as antennae and actuators that reversibly respond to distinct optical signals to switch the polymer-enzyme conjugates on and off, and work when the conjugate is free in solution or when immobilized on magnetic beads. smart polymer ͉ photoswitch ͉ biotechnology ͉ bioMEMs ͉ bioconjugates
Block copolymers containing stimuli-responsive segments provide important new opportunities for controlling the activity and aggregation properties of protein-polymer conjugates. We have prepared a RAFT block copolymer of a biotin-terminated poly(N-isopropylacrylamide) (PNIPAAm)-b-poly(acrylic acid) (PAA). The number-average molecular weight (M(n)) of the (PNIPAAm)-b-(PAA) copolymer was determined to be 17.4 kDa (M(w)/M(n) = 1.09). The PNIPAAm block had an M(n) of 9.5 kDa and the poly(acrylic acid) (PAA) block had an M(n) of 7.9 kDa. We conjugated this block copolymer to streptavidin (SA) via the terminal biotin on the PNIPAAm block. We found that the usual aggregation and phase separation of PNIPAAm-SA conjugates that follow the thermally induced collapse and dehydration of PNIPAAm (the lower critical solution temperature (LCST) of PNIPAAm is 32 degrees C in water) is prevented through the shielding action of the PAA block. In addition, we show that the cloud point and aggregation properties (as measured by loss in light transmission) of the [(PNIPAAm)-b-(PAA)]-SA conjugate also depended on pH. At pH 7.0 and at temperatures above the LCST, the block copolymer alone was found to form particles of ca. 60 nm in diameter, while the bioconjugate exhibited very little aggregation. At pH 5.5 and 20 degrees C, the copolymer alone was found to form large aggregates (ca. 218 nm), presumably driven by hydrogen bonding between the -COOH groups of PAA with other -COOH groups and also with the -CONH- groups of PNIPAAm. In comparison, the conjugate formed much smaller particles (ca. 27 nm) at these conditions. At pH 4.0, however, large particles were formed from the conjugate both above and below the LCST (ca. 700 and 540 nm, respectively). These results demonstrate that the aggregation properties of the block copolymer-SA conjugate are very different from those of the free block copolymer, and that the outer-oriented hydrophilic block of PAA shields the intermolecular aggregation of the block copolymer-SA bioconjugate at pH values where the -COOH groups of PAA are significantly ionized.
Functionalized beads and particles in the size range of tens to hundreds of nanometers (nano- to meso-scale) are finding increased applications in the bioanalytical field. We show here that conjugates of streptavidin and the temperature-responsive polymer poly(N-isopropylacrylamide) (PNIPAAm), synthesized with low polydispersities by reversible addition--fragmentation chain transfer (RAFT) polymerization, rapidly formed mesoscale polymer--protein particles above the lower critical solution temperature (LCST). The average hydrodynamic diameters of these particles could be controlled between 250 nm to 900 nm by the choice of conjugate concentration and polymer molecular weight, and/or through control of the rate of temperature change. Once formed, the biohybrid particles were found to be stable for >16 h at the controlled size, unlike the free PNIPAAm which continued to aggregate and grow over time into very large and polydisperse aggregates. The reversibility between the smart polymer--protein particles and the free polymer--protein conjugates opens potential uses in traditional diagnostic formats and in microfluidic formats where the differential diffusive and physical properties might be exploited for separations, analyte concentration, and signal generation.
Polymers that exhibit a sharp hydrophilic to hydrophobic phase transition on the application of an environmental stimulus such as pH or temperature are called smart polymers. These smart polymers, or stimuli responsive polymers, have been used to develop several drug delivery technologies. The emergence of the fields of nanotechnology and microfluidics has created new opportunities for smart polymers. We have recently developed two nano-and microscale technologies for diagnostic applications. The first is a reversible particle system using stimuli-responsive polymer-protein conjugates. We have found that conjugates of streptavidin and the temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm), rapidly form stable and uniformly sized mesoscale particles above the lower critical solution temperature (LCST) of the polymer. The size of these particles is dependent on concentration, molecular weight of the polymer used and formulation parameters such as the heating rate. The second is a stimuli-responsive bioanalytical bead system. Latex beads were dualconjugated with PNIPAAm and an affinity ligand to confer temperature-responsiveness to the beads. Above the LCST of the PNIPAAm, the bead surface becomes hydrophobic and the modified beads aggregate and adhere to the walls of microfluidic channels. They have been used to develop a reversible microfluidic affinity chromatography matrix for the upstream processing of complex fluids and for immunoassays. Both technologies can be used in a wide variety of formats, including microfluidic-based micro-total analytical systems (μTAS) devices and simple, rapid field tests.
The recent advances in electronics and microelectronics devices allow the development of newly low-cost monitoring tools used by people for health preventive purposes. Sensors used in medical equipment convert various forms of human body vital signs into electrical signals. Therefore, the healthcare monitoring systems considering non-invasive and wearable sensors with integrated communication mediums allow an efficient solution to live a comfortable life at home. The sensors used in this work are a body temperature sensor and a blood oxygen sensor. The method that we used enables us to show the results of the sensor readings to a desktop application, then read the printout of the series and create a visual in the form of tables and graphs, as well as store the data in a database and display the data via a website in the form of reports that can be accessed remotely. The results obtained from the study conclude that, this application can be used to access data remotely.
Technology is rapidly growing and fast and instant network connections have changed life. The use of mobile, tablets, and laptops are increasing. In this fast and information-oriented world, we need to stay updated with every incident and news. The NewsAngle app is an android mobile application where users have access to the latest news from the Admin app. The application has focused on the existing system and tried to solve problems such as the improvised notification system, news with tags, and live news channel option using youtube APIs. A payment gateway is integrated into the system which will help to alter the users into two separate categories like paid and free users. Android studio used in applications supports programming languages like Java, Kotlin, and XML (Extensible Markup Language). The drag-and-drop feature for the user interface and the java code auto-completion feature for the backend have made android studio easy to use. The main focus of the application is to connect news articles from all around the world and deliver to them to users as fast as possible. It provides automation, immediacy, adaption, and personalization. The Application provides information about the stock market, mutual funds, and cryptocurrency. The user can see share market values and live television channels which are displayed in the application.
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