While silver nanoparticles are widely used to endow materials with antibacterial activity, silver nanowires (AgNWs) have not attracted much attention. Herein, the composites of bacterial cellulose (BC) and AgNWs were prepared through a novel step-by-step in situ biosynthesis which retains the three-dimensional network of BC. The results of water vapor permeability, water uptake rate, and water retention rate showed that the BC/AgNW wound dressings could absorb wound skin exudates and maintain moisture environments. Furthermore, the BC/ AgNW dressings were robust and stretchable. More importantly, the BC/AgNW dressings exhibited sustained release of Ag +. The results from animal tests indicated that the BC/AgNW dressing with 38.4 wt% AgNWs exhibited higher expression levels of cytokeratin-10 and integrin-β4, greater proliferation of keratinocytes and formation of epithelial tissues and greatly improved skin regeneration over the bare BC. We propose that the integrated nanofibrous structure and the excellent and sustained antibacterial activity of AgNWs are responsible for the excellent in vivo wound healing ability and biocompatibility. These results suggest that the BC/AgNW composites have promising application as wound dressings.
Organic theranostic nanomedicine has precision multimodel imaging capability and concurrent therapeutics under noninvasive imaging guidance. However, the rational design of desirable multifunctional organic theranostics for cancer remains challenging. Rational engineering of organic semiconducting nanomaterials has revealed great potential for cancer theranostics largely owing to their intrinsic diversified biophotonics, easy fabrication of multimodel imaging platform, and desirable biocompatibility. Herein, a novel all‐organic nanotheranostic platform (TPATQ‐PNP NPs) is developed by exploiting the self‐assembly of a semiconducting small molecule (TPATQ) and a new synthetic high‐density nitroxide radical‐based amphiphilic polymer (PNP). The nitroxide radicals act as metal‐free magnetic resonance imaging agent through shortened longitudinal relaxation times, and the semiconducting molecules enable ultralow background second near‐infrared (NIR‐II, 1000–1700 nm) fluorescence imaging. The as‐prepared TPATQ‐PNP NPs can light up whole blood vessels of mice and show precision tumor‐locating ability with synergistic (MR/NIR‐II) imaging modalities. The semiconducting molecules also undergo highly effective photothermal conversion in the NIR region for cancer photothermal therapy guided by complementary tumor diagnosis. The designed multifunctional organic semiconducting self‐assembly provides new insights into the development of a new platform for cancer theranostics.
Developing fibrous scaffolds with hierarchical structures that closely mimic natural extracellular matrix (ECM) is highly desirable. However, fabricating scaffolds with true nanofibers (< 100 nm) and submicrofibers (< 1 μm) remains a big challenge. In this work, to mimic the fibrillar structure of natural ECM, bacterial cellulose (BC) nanofibers were hybridized with cellulose acetate (CA) submicrofibers for the first time. The interpenetrated nano-submicron fibrous BC/CA scaffold was fabricated using the combined electrospinning and modified in situ biosynthesis method. The BC/CA scaffold has an integrated symmetrical nanostructure in which BC nanofibers (42 nm in diameter) penetrate into the submicrofibrous CA (820 nm in diameter) scaffold. The BC/CA scaffold shows an interconnected porous structure with a high porosity of > 90%. Additionally, the combination of CA submicrofibers with BC nanofibers leads to significantly improved mechanical properties over nanofibrous BC and submicrofibrous CA scaffolds and enlarged pores over nanofibrous BC scaffold. In addition, the biological behaviors of prepared BC/CA on MC3T3-E1 cells were investigated. Results suggested that BC/CA scaffold is beneficial for cell migration and proliferation. Moreover, the BC/CA scaffold shows higher alkaline phosphatase (ALP) activity, and calcium depositions. In addition, the hierarchical structures can effectively improve the expression of osteogenic gene (ALP mRNA and Runx2 mRNA) and protein (ALP). We believe that the methodology might provide biomimetic morphological microenvironments for enhanced tissue regeneration.
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