Preparation And Optical Properties Investigation Of Fluorescent Silicon Nanoparticles For Cu²⁺ Detection

Copper is an important trace element in nature and plays a very important role in various life activities.However,if the copper ion(Cu²⁺)level in drinking water or other environments is too high,it will not only affect the living environment of animals,plants and microorganisms,but also seriously threaten the health and safety of living organisms.Therefore,accurate identification and detection of Cu²⁺is of great importance for environmental monitoring and pollution prevention.Traditional methods for detecting Cu²⁺mainly include electrochemical method,atomic absorption method,inductively coupled plasma atomic emission method etc.These detection methods are often cumbersome,time consuming,and require relatively high operation costs.Therefore,it is particularly important to build a simple,fast response,low cost Cu²⁺ detection platform.Silicon nanoparticle?SiNP?is one of ideal nano-optical probes for biochemical sensors because of their unique optical properties,non-toxicity,and low cost of preparation.Water-disaposable amine functionalized SiNPs?A-SiNPs?with good fluorescence characteristics are synthesized based on a one-step synthesis method under mild condition.A high performance Cu²⁺detection platform is then developed by using the A-SiNPs as an optical probe,which effectively overcomes the shortcomings of traditional Cu²⁺ detection method.The main research contents and results are as follows:1.Development and application of A-SiNPs-based Cu²⁺detection strategyIn this part,the A-SiNPs with strong green fluorescence and light stability was synthesized by use of 3-aminopropyl triethoxysilane?APTES?and L-ascorbic acid?AA?as silicon source and reducing agent,respectively under mild conditions.The excitation and emission spectra,optical stability and the effect of pH on the fluorescence effect of A-SiNPs were investigated systematically.Amine group on the surface of A-SiNPs not only improves the water dispersibility of SiNPs,but also offers the ability of specific Cu²⁺ recognition.Based on the Cu²⁺coordination-induced fluorescence quenching effect,a novel and sensitive Cu²⁺ detection method was constructed with A-SiNPs as an optical probe.The experimental results show that under the optimum condition,the linear range of Cu²⁺detection is 1?M-500?M,and the low detection limit?LOD?is 100 nM,which is much lower than the maximum level?²0?M? of Cu²⁺ in drinking water permitted by the U.S.Environmental Protection Agency?EPA?.In addition,A-SiNPs has been successfully applied to the detection of Cu²⁺ in river water,which confirms the practical application potential of this method.2.Synthesis and optical properties investigation of Rhodamine B doped A-SiNPs?RhB-A-SiNPs?for Cu²⁺ detectionBased on the first work,RhB-A-SiNPs were synthesized by a simply hydrothermal method.In order to optimize the reaction conditions,a series of RhB-A-SiNPs were prepared by adjusting the doping ratio,reaction temperature,reaction time and other related parameters.The fluorescence emission intensity,the number and location of emission peaks and the fluorescence stability of the materials were further studied and evaluated.After optimization,it was determined that RhB-A-SiNPs with high fluorescence intensity,good fluorescence stability and dual emission peaks?A-SiNPs and RhB?were successfully synthesized under the conditions of 1mM RhB doping concentration,160?reaction for 1h.A novel Cu²⁺ detection system based on the coordination of surface amino groups with Cu²⁺ was constructed by using the prepared RhB-A-SiNPs as an optical probe.In this system,the intensities of both SiNPs'and RhB's emission peaks significantly decrease in the presence of Cu²⁺.The dual response in the detection greatly improves the accuracy and reliability of Cu²⁺ detection.Under the optimum condition,the linear range of the prepared RhB-A-SiNPs-based Cu²⁺detection method is 10nM-500?M,and the LOD is 10nM,which is much lower than the maximum permission of Cu²⁺ in drinking water.In this work,the fluorescence intensity and optical stability of A-SiNPs were greatly improved by RhB dopping in the synthesis process.At the same time,the two emission peaks of the prepared RhB-A-SiNPs show significant response to Cu²⁺,ensuring the reliability of the Cu²⁺ detection.In summary,water-dispersible A-SiNPs with high fluorescence intensity and good stability were prepared by a green and simple method.RhB-A-SiNPs with better optical properties and dual emission peaks were obtained by doping RhB.In this paper,two Cu²⁺ detection systems were constructed based on the A-SiNPs and RhB-A-SiNPs,and the sensitive and reliable detection of Cu²⁺ in surface water was successfully realized.Compared with the traditional detection method for Cu²⁺,the detection system based on A-SiNPs has many advantages,such as simple preparation process of raw materials,no further modification,low detection cost,simple and fast detection method,wide detection range and low detection limit.