Bioresponsive hydrogels

Abstract

We highlight recent developments in hydrogel materials with biological responsiveness built in. These 'smart' biomaterials change properties in response to selective biological recognition events. When exposed to a biological target (nutrient, growth factor, receptor, antibody, enzyme, or whole cell), molecular recognition events trigger changes in molecular interactions that translate into macroscopic responses, such as swelling/collapse or solution-to-gel transitions. The hydrogel transitions may be used directly as optical readouts for biosensing, linked to the release of actives for drug delivery, or instigate biochemical signaling events that control or direct cellular behavior. Accordingly, bioresponsive hydrogels have gained significant interest for application in diagnostics, drug delivery, and tissue regeneration/wound healing

Bioelectrocatalytic hydrogels from electron-conducting metallopolypeptides coassembled with bifunctional enzymatic building blocks

“…And, just as function stems from structure, it is also controlled within the protein-engineering scheme of materials design. There are a number of successful examples of hydrogels designed for tissueengineering and drug-delivery applications that use functional protein domains to obtain structural responsiveness to environmental cues (2)(3)(4). These examples include responsiveness to pH (5), temperature (6), shear stress (7), and ligand binding (8,9) among others (refs.…”

Nanotechnology: the word is new but the concept is old. An overview of the science and technology in food and food products at the nanoscale level

“…Controlledrelease devices have been in commercial use for decades for various advantageous purposes: (i) to maintain drug level in its desired therapeutic range with just a single dose, and (ii) localised delivery to a particular body compartment thereby lowering the systemic drug level, reducing need for follow-up care, preserving medications that are rapidly destroyed by the body, and increasing patient comfort and/or compliance (Kost & Langer, 2001;Macleod et al, 1999). One strategy for site-specific release has been the sequestration of a given drug in a pro-form (inactive precursor molecules), that can only be freed by enzymatic hydrolysis (Ulijn et al, 2007). The prodrug is designed such that the required hydrolytic specificity is suited to a disease-specific enzyme which thus triggers drug release from a polymeric prodrug carrier.…”

“…The prodrug is designed such that the required hydrolytic specificity is suited to a disease-specific enzyme which thus triggers drug release from a polymeric prodrug carrier. For example, a cancer-specific enzyme secreted by tumor cells can be used to trigger the release of a therapeutic agent to prevent or reduce metastasis (targeted chemotherapy) (Ulijn et al, 2007). Socalled bioresponsive (or biointeractive) materials are encapsulation/carrier components that are stimulated by particular conditions in the target, and this induced state/change in turn causes a change in the carrier properties, resulting in tightly controlled drug release (Ulijn et al, 2007).…”

“…For example, a cancer-specific enzyme secreted by tumor cells can be used to trigger the release of a therapeutic agent to prevent or reduce metastasis (targeted chemotherapy) (Ulijn et al, 2007). Socalled bioresponsive (or biointeractive) materials are encapsulation/carrier components that are stimulated by particular conditions in the target, and this induced state/change in turn causes a change in the carrier properties, resulting in tightly controlled drug release (Ulijn et al, 2007). This scheme is applicable to developing autonomous systems that can detect disease markers and respond to them to repair the IJFS October 2012 Volume 1 pages 188-210 diseased area (Langer & Tirrell, 2004).…”

Polymers to direct cell fate by controlling the microenvironment

“…In the context of material degradation, materials have been developed that incorporate proteolytic domains [41] or bioactive linkers [42], and their degradation and function is altered by contacting cells. Other bioresponsive polymers change physical properties irreversibly with or without material degradation in response to small molecule receptors/ligands, or cell-secreted factors such as enzymes or enzymatic substrates [43]. Reversibility may often be desired and has been demonstrated in response to cellular ligands [44] and enzymes [45].…”