| Due to their unique physical structures and excellent optical, electrical, magnetic and mechanical properties, nanomaterials have been widely used in the field of biomedicine etc. Among them, gold nanoparticles (AuNPs) have been widely used to develop nanomaterials surface energy transfer (NSET) sensors for biologically active substances, environmental pollutants, and disease markers due to their superior quenching capacity to fluorescence signals. And gold nanoclusters with high fluorescence quantum yield have been widely used as fluorescent label for the detection of vaious targets.In this thesis, new methods for the detections of hyaluronidase (HAase) and staphylococcus aureus (SA) have been established respectively, by employing the fluorescencet gold nanomaterials based on NSET, and aptamer-bound magnetic-beads and antibiotics-functionalized gold nanoclusters based dual molecule recognition strategy.Part 1:A novel one-step facile synthesis of hyaluronic acid functionalized fluorescent gold NSET nanoprobes sensitive to HAase in urine specimen from bladder cancer patients. In this study, we report the one-step facile synthesis of fluorescein isothiocyanate-labeled hyaluronic acid (FITC-HA) functionalized fluorescent AuNPs based NSET nanoprobes (FITC-HA-AuNPs) via chemical reduction of HAuC14 by using FITC-HA as both a reducing and stabilizing agent. Then the FITC-HA-AuNPs NSET nanoprobes were used to detect HAase, a new type of disease marker, based on the specific enzymatic degradation of HAase to HA. Compared with similar work, the FITC-HA-AuNPs nanoprobes were much easier to prepare and the detection sensitivity was also high for HAase to reach a detection limit of 0.63U mL-1. More importantly, they also allowed for rapid HAase detection (within 3 h) even in complex biological specimens (urine specimens from patients with bladder cancer) with satisfactory accuracy (recovery efficiency in the range of 92.77-106.90% with RSD≤4.85%). Our studies suggested that such a novel design of FITC-HA-AuNPs NSET nanoprobes developed for sensitive, rapid and accurate detection of HAase had exciting potentials for clinical diagnosis of HAase-related diseases, such as bladder cancer.Part 2:Aptamer and antibiotics based dual recognition strategy combined with magnetic enrichment and fluorescent assay for specific and sensitive detection of SA. Infectious diseases and food poisoning caused by pathogenic bacteria such as SA have been bringing to serious public health concerns, which makes the specific recognition, sensitive and rapid detection of bacterial is essential and improtant. This study presents a strategy by combining the aptamer and antibiotic-based dual recognition units with magnetic enrichment and fluorescent detection together to achieve specific and sensitive assay of SA in authentic specimen. Aptamer-bound magnetic beads prepared based on the interaction between biotinlyated-aptamer and streptavidin-magnetic beads for specific capture and enriching the target SA. And vancomycin stabilized fluorescent gold nanoclusters (AuNCs@Van) synthesized facilely in one step were used for specific recognition and sensitive quantification of SA. Using this strategy, we achieved successfully detection of SA with detection of a few tens of cells from other bacterial contaminated mixed sample.Compared with similar job, our work not only simplifies the preparation procedure of AuNCs@Van, but also detects the added SA in milk directly with good accuracy. Moreover, aptamer and Van are cheap and widely available. Such aptamer and antibiotics based dual recognition strategy combined with magnetic enrichment and fluorescent assay show promising potential for clinical diagnosis and detects of SA-related infectious diseases and food contamination. |
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