Construction Of Multifunctional Silicon Nanoparticle Probes And Their Uses For Bacterial Detection,Antimicrobial And Tumor Treatment

The development of nanobiotechnology has greatly promoted the application of various nanomaterials in the biomedical field.Among them,fluorescent silicon nanoparticles(SiNPs)featuring strong stable fluorescence,facile surface modification and excellent biocompatibility,have been widely used in bioimaging,biosensing,disease treatment and so on.Herein,we construct multifunctional silicon-based nanoprobes,focusing on their applications for bacterial detection,antimicrobial and tumor treatment.The detailed contents are described as follows:Chapter 1:We first briefly introduce recent achievement of various nanomaterials applied in bacterial detection,antimicrobial and tumor treatment;afterwards,illustrate the development of bacteria-mediated tumor therapy.Next,the progress of silicon nanomaterials-based biomedical application is described.In particular,representative reports concerning SiNPs-based bacterial detection and treatment as well as tumor therapy are reviewed.Finally,we discuss the significance and main research contents of this study.Chapter 2:We develop multifunctional SiNPs probes,which are functionalized with a glucose polymer(GP)and chlorin e6(Ce6),suitable for the detection and photodynamic treatment of Gram-positive and Gram-negative bacterial infections.The constructed nanoprobes can be internalized into bacteria through the ATP-binding cassette(ABC)transporter on the membrane of bacteria.Bacteria could be readily imaged by tracking the green fluorescence of SiNPs and the red fluorescence of Ce6,allowing in vivo detection of as few as 105 CFU.The nanoprobes can generate singlet oxygen under 660-nm illumination to kill bacterial cells,thus being useful for the treatment of bacterial inflammation with high in vivo antimicrobial efficiency(i.e.,98%against Staphylococcus aureus and 96%against Pseudomonas aeruginosa).Chapter 3:We design a novel "nano-genetically engineered bacteria" hybrid system for programmable tumor therapy tuned by light irradiation.Specifically,we have constructed the engineered E.coli expressing tumor necrosis factor ?(TNF-?)at a specific temperature(42?)and one multifunctional SiNPs probe with good photothermal ability,which can be internalized into bacteria.E.coli can actively target and locate in tumor sites.The peak amount of bacterial colonies in tumor is up to 4.6×107 CFU/g,with a high tumor to liver ratio of 7300:1 at day 7 post-injection in vivo.The constructed multifunctional SiNPs probes are able to locate and stay in the tumor site by targeting and being internalized into intratumoral bacteria.With the help of SiNPs probes exhibiting excellent photothermal ability,TNF-? can be expressed at specific temperature by engineered E.coli to kill cancer cells and inhibit tumor growth,improving the efficiency of tumor therapy.Chapter 4:We firstly summarize the main research contents of the whole paper,then illustrate the innovation points and limitations of this study.Finally,the corresponding strategies for addressing above-mentioned limitations are proposed.In summary,this study develops multifunctional SiNPs probes featuring excellent fluorescence performance and benign biocompatibility,which are suitable for bacterial detection,antimicrobial and tumor treatment.Our research provides important scientific values for further exploring the development of SiNPs in the biomedical field.