Detection Of Ferric Ions And Pathogenic Bacteria Based On Antibiotic Functionalized Gold Nanomaterials And Their Study Of Antibacterial Effects

The pollution caused by heavy metals on human health and the natural environment,and the outbreak of food safety and infectious diseases caused by pathogenic bacteria are hot issues in recent years.Heavy metal ions,such as Fe³⁺,are easy to accumulate in organism,leading to biological function disorder and many other serious side effects.Pathogenic bacteria,such as Staphylococcus aureus,can easily lead to bacterial food poisoning,and even threatening human life.Therefore,it is desperately urgent to develop a highly sensitive and selective detection method for monitoring heavy metal ions and pathogens.Based on the excellent optical properties of gold nanomaterials,in this dissertation we established the strategies:（1）to detect Fe³⁺by electron transfer quenching mechanism,（2）to detect pathogenic bacteria using a dual molecular affinity-based F?rster resonance energy transfer（FRET）platform based on the specific recognition of aptamer and the broad spectrum recognition of antibiotic,（3）to develop a novel teicoplanin capped gold nanorods with antibiotics and photothermal dual antibacterial effects to kill bacteria,respectively.The main contents are as follows:Part 1: In this section,the cheap,easily obtained small antibiotic molecule of vancomycin（Van）was employed as reducer/stabilizer for facile one-pot synthesis of water exhibited a bluish fluorescence emission at 410 nm within a short synthesis time about 50 min.Based on the strong fluorescence quenching due to electron transfermechanism by the introduction of ferric ions(Fe³⁺),the Van-AuNCs were interestingly designed for sensitive and selective detecting Fe³⁺with a limit of 1.4 μM in the linear range of 2-100 μM within 20 min.The Van-AuNCs based method was successfully applied to determine Fe³⁺in tap water,lake water,river water and sea water samples with the quantitative spike recoveries from 97.50-111.14% with low relative standard deviations（RSDs）ranging from 0.49-1.87%,showing potential for practical application.Part 2: In this section,we presented a universal and facile one-step strategy for the sensitive and selective detection of pathogenic bacteria using a dual molecular affinity-based F?rster（fluorescence）resonance energy transfer（FRET）platform based on the recognition of antibiotic and aptamer molecules to bacterial cell walls,respectively.As a proof of concept,vancomycin（Van）,and a nucleic acid aptamer were employed in a model dual recognition scheme for detecting Staphylococcus aureus（S.aureus）.Within 30 minutes,by using Van-functionalized gold nanoclusters（Van-AuNCs）and aptamer-modified gold nanoparticles（aptamer-AuNPs）as the energy donor and acceptor respectively,the FRET signal shows a linear variation with the concentration of S.aureus in the range from 20 to 108cfu/mL with a detection limit of 10 cfu/mL.When employed to assay S.aureus in real samples,the dual recognition FRET strategy showed recoveries from 99.00% to the 109.75% with RSDs less than 4%.This establishes a universal detection platform for sensitive,specific,and simple pathogenic bacteria detection,which could have great impact in the fields of food safety monitoring and infectious disease diagnosis.Part 3: Herein,we selected teicoplanin（Teico）,which is a glycopeptide antibiotic composed of a unique aliphatic chain,as the auxiliary surfactant to partly replace the traditional cationic surfactant cetyltrimethyl ammonium bromide（CTAB）to prepare a novel antibiotic functionalized gold nanorods（Teico/CTAB-AuNRs）through seed-mediate growth method.The preliminary study indicated that the Teico/CTAB-AuNRs possess unique both antibiotics and photothermal dual antibacterial effects,providing a potential therapy for infectious disease caused by bacteria.