Electrospun Biomimetic Fibrous Scaffold from Shape Memory Polymer of PDLLA-<i>co</i>-TMC for Bone Tissue Engineering

Multifunctional fibrous scaffolds, which combine the capabilities of biomimicry to the native tissue architecture and shape memory effect (SME), are highly promising for the realization of functional tissue-engineered products with minimally invasive surgical implantation possibility. In this study, fibrous scaffolds of biodegradable poly­(d,l-lactide-<i>co</i>-trimethylene carbonate) (denoted as PDLLA-<i>co</i>-TMC, or PLMC) with shape memory properties were fabricated by electrospinning. Morphology, thermal and mechanical properties as well as SME of the resultant fibrous structure were characterized using different techniques. And rat calvarial osteoblasts were cultured on the fibrous PLMC scaffolds to assess their suitability for bone tissue engineering. It is found that by varying the monomer ratio of DLLA:TMC from 5:5 to 9:1, fineness of the resultant PLMC fibers was attenuated from ca. 1500 down to 680 nm. This also allowed for readily modulating the glass transition temperature Tg (i.e., the switching temperature for actuating shape recovery) of the fibrous PLMC to fall between 19.2 and 44.2 °C, a temperature range relevant for biomedical applications in the human body. The PLMC fibers exhibited excellent shape memory properties with shape recovery ratios of <i>R</i>_r > 94% and shape fixity ratios of <i>R</i>_f > 98%, and macroscopically demonstrated a fast shape recovery (∼10 s at 39 °C) in the pre-deformed configurations. Biological assay results corroborated that the fibrous PLMC scaffolds were cytocompatible by supporting osteoblast adhesion and proliferation, and functionally promoted biomineralization-relevant alkaline phosphatase expression and mineral deposition. We envision the wide applicability of using the SME-capable biomimetic scaffolds for achieving enhanced efficacy in repairing various bone defects (e.g., as implants for healing bone screw holes or as barrier membranes for guided bone regeneration)

Au/Polypyrrole@Fe₃O₄ Nanocomposites for MR/CT Dual-Modal Imaging Guided-Photothermal Therapy: An <i>in Vitro</i> Study

Construction of multifunctional nanocomposites as theranostic platforms has received considerable biomedical attention. In this study, a triple-functional theranostic agent based on the cointegration of gold nanorods (Au NRs) and superparamagnetic iron oxide (Fe₃O₄) into polypyrrole was developed. Such a theranostic agent (referred to as Au/PPY@Fe₃O₄) not only exhibits strong magnetic property and high near-infrared (NIR) optical absorbance but also produces high contrast for magnetic resonance (MR) and X-ray computed tomography (CT) imaging. Importantly, under the irradiation of the NIR 808 nm laser at the power density of 2 W/cm² for 10 min, the temperature of the solution containing Au/PPY@Fe₃O₄ (1.4 mg/mL) increased by about 35 °C. Cell viability assay showed that these nanocomposites had low cytotoxicity. Furthermore, an <i>in vitro</i> photothermal treatment test demonstrates that the cancer cells can be efficiently killed by the photothermal effects of the Au/PPY@Fe₃O₄ nanocomposites. In summary, this study demonstrates that the highly versatile multifunctional Au/PPY@Fe₃O₄ nanocomposites have great potential in simultaneous multimodal imaging-guided cancer theranostic applications

One-Pot Synthesis of MoS₂ Nanoflakes with Desirable Degradability for Photothermal Cancer Therapy

Developing biodegradable photothermal agent holds great significance for potential clinical translation of photothermal therapy. In the current study, one-pot hydrothermal synthesis of MoS₂ nanoflakes with desirable degradation capability was presented. The participation of poly­(acrylic acid) (PAA) in hydrothermal process could not only facilitate the modification of polyethylene glycol (PEG), but also bestow degradability to the prepared MoS₂ nanoflakes. Moreover, the PEGylated hybrid nanoflakes (MoS₂–PPEG) also exhibited excellent stability in various medium and outstanding photothermal properties. Interestingly, MoS₂–PPEG behaved distinctly different degradation rate in diverse condition. The rapid degradation of MoS₂–PPEG was observed in neutral pH solution, whereas much slower degradation occurred in an acidic tumor microenvironment. Furthermore, data indicated that the major degradation product of MoS₂–PPEG was water-soluble Mo-based ion. Meanwhile, the good in vitro biocompatibility of MoS₂–PPEG was also confirmed in terms of cytotoxicity and hemolysis. With favorable photothermal performance, MoS₂–PPEG can efficiently killing cancer cells in vitro and suppress the tumor growth in vivo. More importantly, the gradual decreasing content of MoS₂–PPEG in organs and detectable Mo element in urine of mice suggested that the degradability of MoS₂–PPEG might facilitate its excretion to some degree. Hence, the degradable MoS₂ nanoflakes prepared by one-pot hydrothermal routine may provide insight for further biomedical applications of inorganic photothermal agent

Marriage of Albumin–Gadolinium Complexes and MoS₂ Nanoflakes as Cancer Theranostics for Dual-Modality Magnetic Resonance/Photoacoustic Imaging and Photothermal Therapy

The construction of safe and stable theranostics is beneficial to realize simultaneous cancer diagnosis and treatment. In this study, bovine serum albumin–gadolinium (BSA–Gd) complexes and MoS₂ nanoflakes (MoS₂–Gd–BSA) were successfully married as cancer theranostics for dual-modality magnetic resonance (MR)/photoacoustic (PA) imaging and photothermal therapy (PTT). BSA–Gd complexes were prepared by the biomineralization method and then conjugated with MoS₂ nanoflakes via an amide bond. The as-prepared MoS₂–Gd–BSA possessed a good photostability and photothermal effect. The cytotoxicity assessment and hemolysis assay suggested the excellent biocompatibility of MoS₂–Gd–BSA. Meanwhile, MoS₂–Gd–BSA could not only achieve in vivo MR/PA dual-modality imaging of xenograft tumors, but also effectively kill cancer cells in vitro and ablate the xenograft tumors in vivo upon 808 nm laser illumination. The biodistribution and histological evaluations indicated the negligible toxicity of MoS₂–Gd–BSA both in vitro and in vivo. Thus, our results substantiated the potential of MoS₂–Gd–BSA for cancer theranostics