Abstract
Stimuli-responsive anisotropic microstructures and nanostructures with different physicochemical properties in discrete compartments, have been developed as advanced materials for drug delivery systems, tissue engineering, regenerative medicine, and biosensing applications. Moreover, their stimuli-triggered actuations would be of great interest for the introduction of the functionality of drug delivery reservoirs and tissue engineering scaffolds. In this study, stimuli-responsive bicompartmental nanofibers (BCNFs), with completely different polymer compositions, were prepared through electrohydrodynamic co-jetting with side-by-side needle geometry. One compartment with thermo-responsiveness was composed of methacrylated poly(N-isopropylacrylamide-co-allylamine hydrochloride) (poly(NIPAM-co-AAh)), while the counter compartment was made of poly(ethylene glycol) dimethacrylates (PEGDMA). Both methacrylated poly(NIPAM-co-AAh) and PEGDMA in distinct compartments were chemically crosslinked in a solid phase by UV irradiation and swelled under aqueous conditions, because of the hydrophilicity of both poly(NIPAM-co-AAh) and PEGDMA. As the temperature increased, BCNFs maintained a clear interface between compartments and showed thermally-induced actuation at the nanoscale due to the collapsed poly(NIPAM-co-AAh) compartment under the PEGDMA compartment of identical dimensions. Different model drugs, bovine serum albumin, and dexamethasone phosphate were alternately loaded into each compartment and released at different rates depending on the temperature and molecular weight of the drugs. These BCNFs, as intelligent nanomaterials, have great potential as tissue engineering scaffolds and multi-modal drug delivery reservoirs with stimuli-triggered actuation and decoupled drug release.
Highlights
Development of stimuli-responsive, multi-compartmentalized microstructures or nanostructures in the form of particles, cylinders, and fibers has increased interest in a variety of industrial and biomedical applications because they have different physicochemical, optical, and electromagnetic properties and environmental sensitivity in each compartment (Bhaskar et al, 2009; Rahmani and Lahann, 2014)
As reported in bigels having anisotropically distributed poly(NIPAM) with lower critical solution temperature (LCST) behavior (Hu et al, 1995), the poly(NIPAM-co-AAh) compartment at 40◦C showed a dramatic volume decrease compared to its volume at 10◦C due to contraction of poly(NIPAMco-AAh) chains in the networks, while no significant volume change below or above LCST occurred in the poly(ethylene glycol) dimethacrylates (PEGDMA) compartment
When dexamethasone 21-phosphate (DMP) and bovine serum albumin (BSA) as small molecular and biomacromolecular model drugs were separately encapsulated within these bicompartmental nanofibers (BCNFs), the in vitro release rates of the model drugs in phosphate buffered saline (PBS) were largely affected by temperatureinduced volume changes of the poly(NIPAM-co-AAh) and PEGDMA compartments
Summary
Development of stimuli-responsive, multi-compartmentalized microstructures or nanostructures in the form of particles, cylinders, and fibers has increased interest in a variety of industrial and biomedical applications because they have different physicochemical, optical, and electromagnetic properties and environmental sensitivity in each compartment (Bhaskar et al, 2009; Rahmani and Lahann, 2014). Both the methacrylated poly(NIPAM-co-AAh) and PEGDMA in the distinct compartments were chemically crosslinked in a solid phase by UV irradiation and stabilized under aqueous conditions.
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