Intelligent Cellulose Nanofibers with Excellent Biocompatibility Enable Sustained Antibacterial and Drug Release via a pH-Responsive Mechanism

Abstract

Novel nanosized biomass-based pH-responsive cellulose nanofibers (CNF-PEI) with excellent biocompatibility were tailored by grafting polyethylenimine (PEI) onto carboxylated cellulose nanofibers (CNF-COOH); the active site (−COOH, 0.96 mmol/g) was anchored on cellulose nanofibers (CNFs) to introduce PEI with a high density (10.57 mmol/g) of amino groups. The as-prepared CNF-PEI not only maintained the good properties of CNFs but also possessed excellent biocompatibility and pH-responsive properties, offering interesting possibilities for pH-induced sustained drug release and medical dressing. The CNF-PEI showed rapid wettability conversion from hydrophilic, underwater superoleophobic (WCA = 20.7°, OCA = 159.3°) to hydrophobic, superoleophilic (WCA = 129.6°, OCA = 29.7°) in response to pH change from acidic conditions to alkaline conditions. The antibacterial activity of CNF-PEI toward Escherichia coli and Listeria monocytogenes was 100% and 94.6% under acidic conditions, respectively. Furthermore, the pH-responsive mechanism of CNF-PEI was revealed by XPS, 13C NMR, 1H NMR, and AFM analyses.

Bioactive Poly(lactic acid)–Cocoa Bean Shell Composites for Biomaterial Formulation: Preparation and Preliminary In Vitro Characterization

“…Following MTT cytotoxicity assay (Figure 5a,b), in all cases, Vero cells were metabolically active with cell viability levels above 94% after 24 and 72 h of exposure to the treatments. The negligible impact on cell viability of our composites agrees well with cytotoxicity assays reported previously for cocoa-and parsley-derived fibroin [35,79] and are superior to those obtained for bagasse [15]. This verifies that the incorporation of CBS into the PLA matrix was not detrimental for the cells, and it could be potentially employed as a bioactive filler in smart biomaterial development.…”

“…However, important disadvantages include the high cost and the need for unique chemical modifications to comply with the attributes for specific applications, as is the case of developments for tissue engineering, such as regeneration of bone, cartilage, and skin, as well as the manufacture of vascular grafts [14]. Conversely, PLA has gained significant popularity as a matrix for bio-inspired composite formulation and fabrication, along with other biopolymers of the polysaccharides family, such as chitosan, alginate, and cellulose [15]. However, the mechanical properties of the obtained composites are below those of most human tissues, limiting their applicability as a medical device.…”

Bio-Based Electrospun Fibers for Wound Healing

“…Especially, the stimuli-responsive drug delivery systems are promising materials for generating smart wound dressings. These materials, with the ability to tune drug release in response to stimuli of pH [71][72][73][74], temperature [71,75,76], light irradiation [11,75], electric field [77], and oxygen [11,78] hold remarkable promise for wound healing.…”

Intelligent Polymers, Fibers and Applications

“…As a promising approach especially in cancer treatments, localized drug-delivery carriers made by polymers decrease the toxicity of the drug and, via site-specific release, enhance the effect of the active compounds [ 73 , 106 , 118 , 132 ]. For example, intelligent biocompatible cellulose nanofibers (CNF) developed by He et al [ 133 ] enable sustained drug release via the pH responsiveness of grafted polyethylenimine (PEI). The generated CNF-PEI displayed a rapid response to pH, reflected by its wettability, converting to hydrophobicity when surrounding pH changed from acidic to alkaline and returning to hydrophilicity when pH conditions reversed back.…”