Hydrophilic polymers are the center of research emphasis in nanotechnology because of their perceived “intelligence”. They can be used as thin films, scaffolds, or nanoparticles in a wide range of biomedical and biological applications. Here we highlight recent developments in engineering uncrosslinked and crosslinked hydrophilic polymers for these applications. Natural, biohybrid, and synthetic hydrophilic polymers and hydrogels are analyzed and their thermodynamic responses are discussed. In addition, examples of the use of hydrogels for various therapeutic applications are given. We show how such systems' intelligent behavior can be used in sensors, microarrays, and imaging. Finally, we outline challenges for the future in integrating hydrogels into biomedical applications.

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We report on a pH sensor with ultrahigh sensitivity based on a microcantilever structure with a lithographically-defined crosslinked copolymeric hydrogel. Silicon-on-insulator wafers were used to fabricate cantilevers on which a polymer consisting of poly(methacrylic acid) (PMAA) with poly(ethylene glycol) dimethacrylate was patterned using free-radical UV polymerization. As the pH around the cantilever was increased above the pKa of PMAA, the polymer network expanded and resulted in a reversible change in surface stress causing the microcantilever to bend. Excellent mechanical amplification of polymer swelling as a function of pH change within the dynamic range was obtained, with a maximum deflection sensitivity of 1 nm/5×10−5 ΔpH.

In the past few years, there has been increased interest in the development and applications of hydrogel nanocomposites, specifically as a new class of biomaterials. In some cases, the nanoparticles (e.g., gold, magnetic, carbon nanotubes) can absorb specific stimuli (e.g., alternating magnetic fields, near-IR light) and generate heat. This unique ability to remotely heat the nanocomposites allows for their remote controlled (RC) applications, including the ability to remotely drive the polymer through a transition event (e.g., swelling transition, glass transition). This review highlights some of the recent studies in the development of the RC hydrogel nanocomposites. In particular, some of the important applications of RC nanocomposites as RC drug delivery devices, as RC actuators, and in cancer treatment are discussed.

This article presents recent achievements and trends in high-speed indoor visible light communication (VLC) research. We address potential applications and future visions for the VLC technology, where transport of information is “piggybacked” on the original lighting function of LED-based lamps. To mature this technology and transfer it into practice, our recent research is focused on real-time implementation and trials. For the first time, a bidirectional real-time VLC prototype achieving data rates of up to 500 Mb/s is presented. This system paves the way for future real world applications. Finally, we discuss the remaining technical challenges as well as the research outlook in the field of high-speed VLC systems