Combining Host−Guest Systems with Nonfouling Material for the Fabrication of a Biosurface: Toward Nearly Complete and Reversible Resistance of Cytochrome c

Abstract

In this letter, a pH-responsive reactivated biointerface is fabricated using an inclusion reaction between an azobenzene-containing self-assembled monolayer and pH-responsive poly(ethylene glycol)-block-poly(acrylic acid) grafted with cyclodextrins. The pH-responsive interface can be switched between an extended state and a relaxed state for the reversible resistance of cytochrome c adsorption completely in cooperation with protein-resistant poly(ethylene glycol).

Smart Biointerface with Photoswitched Functions between Bactericidal Activity and Bacteria-Releasing Ability

“…Dynamic control of cell behavior on material surfaces is of great importance for both fundamental research in cell biology and practical applications such as tissue engineering, drug delivery, and cell-based diagnostics. − In recent years, increasing efforts have been made to construct so-called “smart” biointerfaces with switchable functions to regulate cell–surface interactions in response to changes in external stimuli. − Among the available stimuli, light is particularly attractive due to its noninvasive and intrinsically clean nature, making it suitable to be used in biological systems without risk of compromising normal biological function. − A widely used strategy to construct photoresponsive biointerfaces is to attach photoswitchable molecules onto solid supports. For example, azobenzene (Azo) is a photoresponsive molecule that could reversibly form inclusion complexes with host molecules such as cyclodextrin (CD) in response to light of different wavelengths. , The rodlike trans Azo forms a stable complex with CD, whereas the “bent” cis Azo does not fit in the CD cavity due to size mismatch. − Several dynamic supramolecular platforms based on Azo/CD have been developed for remote control of biointerfacial interactions such as capture and release of mammalian cells , and bacteria …”

Solvothermal synthesis of FeCo nanoparticles for magneto-controllable biocatalysis

“…In addition, effective immobilization of enzymes on surfaces without conformation change and denaturation is crucial for potential applications in the areas of bioelectrochemistry, 21 biocatalysis, [22][23][24] bioassays 25,26 and bioengineering. 27,28 In order to maintain the natural biocatalytic activity and stability, and improve the reusability of the enzymes from the reaction systems, a large number of functional carriers have been employed to immobilize enzymes. 29,30 For instance, immobilizing enzymes on MNPs has received considerable attention not only due to the availability of large specic surface areas and stability of the adsorption of targeted cargos, but also because of their efficient control and directional separation from a reaction mixture by an external magnetic eld.…”

The increasing dynamic, functional complexity of bio-interface materials

“…55 On the other hand, while light as a stimulus is independent on the material used, an electrical and magnetic stimulus requires an electrically conducting and magnetic substrate material, respectively. Irreversible photocleavage of o-nitrobenzyl derivatives 50 and reversible photo-triggered isomerization of spiropyran 51 and azobenzene 52 moieties are photoreactions commonly used to achieve photo-switchable bio-interfaces. Electrically responsive surfaces operate generally under similar trigger-induced modifications as photo-switchable surfaces, where the hydroquinonequinone redox couple, 19 charged molecular backbones 53 or end groups 56 and conductive polymers, such as PEDOT, 54 feature prominently as the switching units.…”

“…In order to meet the design criterion of simplicity of operation, temperature-and pHresponsive surfaces have been the most widely investigated responsive surfaces for integration in bioseparation processes by relying mainly on their capability to control hydrophobic and electrostatic interactions. For instance, a cyclodextrin-grafted pH-responsive poly(ethylene glycol)block-poly(acrylic acid) immobilised on an azobenzene-terminated SAM is able to reversibly expose a negative or neutral charge depending on the pH, inducing the capture or release of the positively charged protein cytochrome c. 52 Whereas these systems, which are based on non-specific interactions, are able to meet some of the bioseparation end uses, the remaining challenge today is to promote a high degree of selectivity while creating a fully reversible system. In order to achieve this goal, an ingenious chemomechanical sorting system has been devised to catch and release target biomolecules from a solution mixture.…”