Unconventional and facile production of a stimuli-responsive multifunctional system for simultaneous drug delivery and environmental remediation

Abstract

Herein, pH-responsive poly 4-hydroxyphenyl methacrylate single-walled carbon nanotube (PHPMA-SWCNT = f-CNT)/PE nanocomposite (NCST) fiber membranes were developed for stimuli-responsive drug delivery and the selective removal of Pb²⁺ and Cd²⁺ from wastewater. The NCST fiber membranes were primed using Forcespinning®, followed by a heat pressure method. The obtained NCST membranes exhibited several favorable properties of nanocarriers and nanoadsorbents. The composite membrane displayed record-high tensile strength (13.7 ± 3.2 GPa), Young's modulus (243.3 ± 5.2 GPa), and toughness (1421 J g⁻¹). This represents the strongest and stiffest composite material among all the reported nanocomposites to date. A hydrophobic drug molecule (curcumin (Cur))-encapsulated NCST membrane displayed a pH-mediated Cur release in a controlled manner. The NCST membrane displayed excellent cell viability against human osteoblast cells. Owing to the f-CNT incorporation, the composite membrane exhibited excellent adsorption capability for Pb²⁺ and Cd²⁺ ions. The selectivity adsorption test indicated that NCST fibers possess a higher affinity towards both Pb²⁺ and Cd²⁺ from wastewater comprising multiple interfering ions. The NCST adsorbent presented a high adsorption capacity for Pb²⁺ (213.18 mg g⁻¹) and Cd²⁺ (165.37 mg g⁻¹) under an optimal pH of 6.0 at room temperature. The adsorption kinetics and isotherm studies of the adsorbent revealed that the adsorption experiments obeyed the pseudo-second-order and Langmuir isotherm model. After six adsorption/desorption cycles, the adsorbent could still maintain its adsorption efficiency. Nonetheless, the robust composite membranes with inherent stimuli-responsive drug delivery and heavy metal adsorption properties can be considered promising multifunctional nanomaterials for biomedical applications and environmental remediation.