Thermoresponsive Polymer Gating System on Mesoporous Shells of Silica Particles Serving as Smart Nanocontainers

Abstract

Spherical silica nanoparticles with solid cores and mesoporous shells (SCMS) were decorated with thermoresponsive polymer brushes that were shown to serve as macromolecular valves to control loading and unloading of a model dye within the mesopores. Thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) brushes were grafted from the surfaces of both solid core (SC) and SCMS particles of similar size using surface-initiated atom transfer radical polymerization. Both systems based on porous (SCMS-PNIPAM) and nonporous (SC-PNIPAM) particles were characterized using cryo-TEM, thermogravimetry and elemental analysis to determine the structure and composition of the decorated nanoparticles. The grafted PNIPAM brushes were found to be responsive to temperature changes enabling temperature-controlled gating of the pores. The processes of loading and unloading in the obtained systems were examined using a model fluorescent dye—rhodamine 6G. Polymer brushes in SCMS-PNIPAM systems were shown to serve as molecular valves enabling significant adsorption (loading) of the dye inside the pores with respect to the SC-PNIPAM (no pores) and SCMS (no valves) systems. The effective unloading of the fluorescent cargo molecules from the decorated nanoparticles was achieved in a water/methanol solution. The obtained SCMS-PNIPAM particles may be used as smart nanocontainers or nanoreactors offering also facile isolation from the suspension due to the presence of dense cores.

Enhanced Thermal Conductivity of Polyamide-Based Nanocomposites Containing Graphene Oxide Sheets Decorated with Compatible Polymer Brushes

“…Moreover, the N-H vibration mode appearing at 1626 cm −1 for GO_APTES was shifted to 1632 cm −1 in GO_BIBB, indicating the attachment of BIBB [32]. However, the larger intensity of this broader band for GO_APTES may also be attributed to the presence of residual water (also adsorbed from air), as it was previously observed for APTES layers [33] and correlates here with the strong band in the 3000-3600 cm −1 range. The obtained GO_BIBB was then used to perform SI-ATRP of acrylamide (Figure 1, step 3).…”

Silica-Based Stimuli-Responsive Systems for Antitumor Drug Delivery and Controlled Release

“…Another recently described example also uses the temperature-sensitive polymer PNI-PAM to develop hybrid nanoparticles that can be used as reservoirs for molecules [33]. SNPs with solid cores (porous (SCMS) and non-porous (SC)), with a diameter of about 380 nm, and porous shells conjugated with thermosensitive PNIPAM brushes were synthesized using a two-step method.…”

Mesoporous Silica Nanoparticles: Properties and Strategies for Enhancing Clinical Effect

“…Multiple gatekeeper formulations requiring external stimuli were paired with MSNs. Primarily, these gatekeepers are thermosensitive in nature, requiring an increase of site-specific in vivo temperature [ 170 ]. Induction of localized hyperthermia results in degradation or alteration in the polymer network, releasing the payload.…”

“…The thermosensitive behavior of PNIPAM can be maintained when properly copolymerized with other polymers, such as methacrylic acid, as shown in Figure 4. in nature, requiring an increase of site-specific in vivo temperature [170]. Induction of localized hyperthermia results in degradation or alteration in the polymer network, releasing the payload.…”