季铵化介孔碳纳米球的合成及其在体内协同光热抗菌治疗

Quaternized mesoporous carbon nanospheres for synergistic antibacterial therapy in vivo

细菌感染对人类健康造成了严重威胁,光热抗菌疗法(photothermal antimicrobial therapy, PTT)具有广谱抗菌、时空可控性、微创性和深组织穿透性等优点.然而,单一PTT治疗常常伴随着热损伤等副作用,影响治疗效果.协同光热疗法能够克服这个问题.本研究首先制备富含羧基的介孔碳纳米球(carboxy-rich mesoporous carbon nanospheres, CMCN),再共价接枝聚乙烯亚胺并进行季铵化(quaternary ammonium compound, QAC)处理制备得到CMCN-QAC复合材料.本研究分析了CMCN浓度和照射功率对温度的影响,评估其光热性能.接下来,采用平板涂布法和活/死染色等实验分析CMCN-QAC体外协同光热抗菌效果.最后,建立小鼠创面细菌感染模型并进行协同光热治疗.结果表明, CMCN-QAC在体内外均表现出优异的治疗效果和良好的生物相容性,体现了CMCNQAC作为新型协同光热抗菌材料在治疗细菌感染领域的潜力.

Photothermal antimicrobial therapy(PTT) has more advantages than traditional antimicrobial therapy. Photothermal conversion nanomaterials can convert optical energy into thermal energy for killing bacteria under near-infrared light. Compared with antibiotic therapy, PTT has several advantages, such as broad-spectrum antimicrobial performance, spatiotemporal specificity, minimally invasive, and deep tissue penetration, and does not cause bacterial resistance. Nevertheless, the therapeutic effect of PTT monotherapy is not ideal because it is often accompanied by side effects, such as thermal injury. To overcome this shortcoming,synergistic photothermal therapy has attracted extensive research interests. This study first synthesized mesoporous carbon nanospheres(MCNs) with commendable solar-thermal conversion performance and uniform size. Then, carboxy-rich MCNs(CMCNs) were obtained by heating in a mixed acid solution. Subsequently, polyethyleneimine(PEI) was covalently grafted onto the surface of CMCNs using the 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide(EDC) and N-hydroxysuccinimide(NHS) coupling reaction. Finally, quaternized mesoporous carbon nanospheres(CMCN-QAC) was obtained using a quaternization reaction. The morphology and crystalline forms of MCNs were analyzed using scanning electron microscopy and X-ray diffraction. The photothermal conversion performance of CMCNs was evaluated using an infrared thermal imager. It was found that the photothermal conversion performance of CMCNs was related to the material concentration and the 808-nm near-infrared laser irradiation power intensity. Moreover, photothermal stability experiments were conducted, and the results show that the CMCNs has stable photothermal conversion performance and stability. Next, the spread plate method and live/dead staining experiments were conducted to study the synergistic photothermal antibacterial effect of CMCN-QAC in vitro. The MBC value of CMCN-QAC was 60-μg/mL under 1.5-W/cm~2 808-nm near infrared(NIR) laser for 10 min. Finally, to investigate the synergistic photothermal therapy of CMCNQAC in vivo, we established a mouse model of wound infection induced by Escherichia coli. The in vitro and in vivo results showed that the CMCN-QAC+NIR group exhibited the best therapeutic effect and high biocompatibility, indicating that CMCN-QAC has great potential to serve as a novel synergistic photothermal antimicrobial nanomaterial to treat bacterial infections.