Surface design with self-heating smart polymers for on–off switchable traps

Abstract

We have developed a novel self-heating, temperature-responsive chromatography system for the effective separation of biomolecules. Temperature-responsive poly(N-isopropylacrylamide-co-N-hydroxymethylacrylamide), poly(NIPAAm-co-HMAAm), was covalently grafted onto the surface of magnetite/silica composites as 'on-off' switchable surface traps. The lower critical solution temperature (LCST) of the poly(NIPAAm-co-HMAAm)s was controlled from 35 to 55• C by varying the HMAAm content. Using the heat generated by magnetic particles in an alternating magnetic field (AMF) we were able to induce the hydrophilic to hydrophobic phase separation of the grafted temperature-responsive polymers. To assess the feasibility of the poly(NIPAAm-co-HMAAm)-grafted magnetite/silica particles as the stationary phase for chromatography, we packed the particles into the glass column of a liquid chromatography system and analyzed the elusion profiles for steroids. The retention time for hydrophobic steroids markedly increased in the AMF, because the hydrophobic interaction was enhanced via self-heating of the grafted magnetite/silica particles, and this effect could be controlled by changing the AMF irradiation time. Turning off the AMF shortened the total analysis time for steroids. The proposed system is useful for separating bioactive compounds because their elution profiles can be easily controlled by an AMF.

Rapid Phase Separation in Aqueous Solution of Temperature‐Sensitive Poly(N,N‐diethylacrylamide)

“…What is important here is that phase separation in PDEA is rapid compared with PNIPAM systems. Such a rapid response would be valuable in several applications such as in sensors, actuators and drug delivery systems . Contrary to τ slow , τ fast seems to be insensitive to pc , and is almost constant at 5 ms, suggesting that τ fast is independent of r .…”

“…Such unique behavior has attracted a broad spectrum of interest from basic research to applications. In several applications, such as sensors, actuators, and drug delivery systems, it is very important that there is appropriate control of the temporal response . It should be noted that the kinetics of the volume‐phase transition in thermoresponsive polymer gels have been clearly elucidated both by experiment and in theoretical studies .…”

A Smart Hyperthermia Nanofiber with Switchable Drug Release for Inducing Cancer Apoptosis

“…AMF‐Induced Heat Generation Properties : The heat generation properties of the MNP‐loaded nanofibers were investigated by applying an alternating magnetic field (AMF, HOTSHOT2, Ameritherm, USA) 32. Approximately 5, 15 and 25 mg of the DOX/MNPs‐nanofibers were immersed in PBS (300 μL) at 4 °C and swollen for 10 min.…”

Smart Biomaterials

“…In addition, it becomes increasingly apparent that on-demand switchable materials that can respond to external stimuli or their environment to produce dynamic and reversible change in critical properties have enabled progress in a growing number of diverse applications including bio/chemical analysis, chemical synthesis, cell manipulation, biomedical monitoring, and point-of-care clinical diagnostics. The 'on-off' switchable surface trap systems have also been developed to separate and enrich target analytes with simple control of the external stimuli such as friction heat, light and magnet for point-of-care diagnostics in the low-infrastructured sites [275][276][277][278]. Beebe and co-workers, for example, used a pH-responsive hydrogel-based valve that opened or closed depending upon the pH of the flowing solution [268].…”