Design and Sensing Application of Metal Nanoclusters-based Ratiometric Fluorescent Sensors

Author:Jia Yun Xiao

Supervisor:wang gui bin


Degree Year:2019





Temperature is a very important parameter in almost all chemical and biological processes.Intracellular temperature measurement and thermal imaging can not only help increase the understanding of various cellular mechanisms,but also detect many diseases at the cellular level,as well as develop new diagnostic and therapeutic techniques.Considering the non-obvious temperature fluctuation and non-uniform space heating of human tissues or cells,high spatial resolution、high sensitivity and specificity detection of physiological temperature(20-50 ℃)will be helpful to understand the biochemical process during temperature change.However,up to now,people have not fully understood how cells perceive and respond to temperature at the molecular and organelle levels.Temperature heterogeneity of living cells is still an open question.Therefore,it is very necessary to develop different kinds of micro-nanothermometers with different functions in temperature measurement.Many studies have found that nano-temperature probe based on luminescence is very suitable for such applications,including quantum dots,metal nanoclusters,rare earth metal complexes,thermosensitive polymers,gene-coded protein probes and so on.Compared with previous single-light intensity-dependent fluorescence sensors,dual-light ratio fluorescence probes have attracted much attention due to their distinguishable luminescence properties of two different excited states.They can reduce the influence of external factors,such as excitation fluctuation,detection efficiency,probe concentration,optical shielding or other local inhomogeneity that changes absolute intensity.In the second chapter,we desigh a simple、fast and green ultrasound method to synthesize large quantities of fluorescent gold nanoclusters GSH-Au NCs.The synthesized GSH-Au NCs have small monodisperse size(1.7 nm)and bright orange-red fluorescence emission(Em=598 nm)in aqueous solution.The prepared GSH-Au NCs have excellent structural stability,good irradiation stability,time stability,salt and acid-base stability.They exhibit high selectivity and detection sensitivity to Cu2+.With the increase of Cu2+ concentration,the fluorescence of GSH-Au NCs decreases gradually,with the LOD of 20 ppb.At the same time,they can sensitively detect temperature in a wide temperature range(20-80 ℃).The prepared GSH-Au NC has potential to become a dual sensor probe for Cu2+ and temperature in the biological field.In the third chapter,CDs/Au NCs dual fluorescence emission hybrid nanomaterials are prepared by simple electrostatic interaction.Under the excitation of 380 nm,the synthesized hybrid nanomaterials exhibit ideal fluorescence double emission behavior,with two fluorescent peaks of high resolution,comparable intensity and completely different color.Hybrid nanothermometer can be used for temperature colorimetric detection in the range of 20-80 ℃,with high sensitivity and reproducibility.In addition,the CDs/Au NCs dual-emission nanomaterials have excellent stability and biocompatibility which have been denmostrated to be used to detect temperature in cells.They are promising candidate materials for intracellular imaging and temperature sensing at subcellular level.In the fourth chapter,yellow fluorescent CDs was dripped into PU(water/glycerol)solution according to the mass ratio.Finally,the hybrid PU/CDs film with yellow-blue double light emission was obtained after heating and drying the mixed droplets on glass substrate.The distribution of CDs on the composite film is relatively uniform,and the transmittance of the hybird film reaches more than 77%,with good tensile and ductility.Based on the properties of double emission color changing with temperature,we selected the composite film prepared with the optimum ratio of PU:CDs with the CDs content of 1%.It has ideal temperature response of double emission fluorescence with a large color changing span.With the temperature increasing,it moves from blue to green to yellow,sensitively and accurately.The hybrid PU/CDs films prepared in this chapter can be used for temperature sensitive colorimetric detection in a wide temperature range(10-90 ℃).They have high application value in both macroscopic dual-light temperature detection and polymer composite modification.