Construction And Detection Application Of Visual Probe Based On Noble Metal Nanoparticles

In recent years,nanomaterials,especially noble metal nanomaterials,have attracted extensive attention from researchers at home and abroad.When metal nanoparticles are coupled with electromagnetic radiation,their plasma response can be widely used in sensing,photocatalysis,electronics,biomedicine and other fields.Among them,the application of noble metal nanoparticles in the field of sensing(such as colorimetry,fluorescence,etc.)is particularly concerned.However,there are many problems and challenges for noble metal nanoparticles in these sensing applications.In the colorimetric detection,on the one hand,most precious metal nanoparticles have poor stability and are easy to be interfered by environmental factors,resulting in lower accuracy of detection.On the other hand,most noble metal nanoparticles only respond to a single signal,which is easy to cause false positive misjudgment.Most noble metal nanoparticles have poor stability in fluorescence detection.Based on the above problems of precious metal nanoparticles,three kinds of visual probes based on precious metal nanoparticles are designed in this paper.On the one hand,gold nanoparticles(Gel-Au NPs)prepared by gelatin in situ were used to construct a highly stable gold-platinum(Au-Pt)nano-visual probe based on Gel-Au NPs,which could produce color and ultraviolet changes for I~-detection,and improve the sensitivity and accuracy of detection.Secondly,a temperature-sensitive visual probe was constructed based on gold nanoparticles(Au NPs),which produced double changes of color and turbidity in temperature detection,thus avoiding misjudgment caused by false positive signals.Thirdly,the high stability silver nanoparticles(Ag NPs)visual probe was constructed to produce fluorescence changes for p H detection,which significantly improved the accuracy of detection.1.Gel-Au NPs were prepared by in-situ reduction of chlorauric acid using gelatin as reducing agent,and then a visible probe of Au-Pt alloy nanoparticles was prepared by reacting with chlorplatinic acid.The probe was characterized by XPS,TEM,DLS and Zeta potential,and the thermal stability and salt stability of the probe were investigated.The presence of I~-can cause the color and ultraviolet changes of Au-Pt alloy nanoparticles.As a response signal,Au-Pt alloy nanoparticles can be applied to the visual detection of I~-.The results show that the Au-Pt alloy nanoparticles with 50?C high heat resistance and high salt resistance of 12 g/L,broaden its application scope.Au-Pt alloy nanoparticles showed good sensitivity and selectivity for I~-detection,and the detection limit was 0.26μM.At the same time,the probe system also showed high sensitivity and accuracy for the detection of I~-in seawater and tap water.Therefore,the visual probe of Au-Pt alloy nanoparticles based on Gel-Au NPs has great potential for I~-detection and analytical applications.2.The functional temperature-sensitive polymer HPEi-IBam was prepared by isobutylated hyperbranched polyethylenimide(HPEI)and characterized by ~1HNMR.Then,Au NPs were prepared by reducing chlorauric acid with sodium citrate,and a temperature-sensitive HPEI-IBAm-Au NPs visual probe was prepared by combining the two methods.The probe was characterized by XPS,TEM,DLS and Zeta potential,which proved that the probe was successfully prepared.Based on the excellent properties of HPEI-IBAm,the probe has good stability.The detection conditions were optimized,and the color,turbidity point and ultraviolet spectrum changes of the probe under the optimal experimental conditions were tested,and the influence of the temperature range on the probe during wound infection was explored.According to the results,HPEI-IBAm-Au NPs visual probe in 33-34?C produced in pink to purple color changes,from clear to turbid solution at the same time.What’s more,when the temperature is cooled again,the probe can be returned to a near original state.In addition,the same result is obtained in the detection of ambient temperature by the probe.Therefore,the visual probe can give an obvious signal response within the range of temperature variation caused by wound infection,and can be used for temperature detection and environmental temperature detection,which lays a foundation for temperature monitoring,especially for wound infection.3.A series of Ag NPs visual probes were prepared by reducing silver nitrate with HPEI as reducing agent and ascorbic acid as reducing agent at different p H values.The probe was characterized by TEM,EDS,DLS and Zeta potential,which proved that the probe was successfully prepared.The preparation conditions of Ag NPs were optimized by orthogonal experimental design.Based on the characteristics of multi-functional groups and hyperbranched structure of HPEI,the prepared Ag NPs have good stability.The fluorescence properties of the probe were tested at different p H values under optimal experimental conditions.The results showed that the fluorescence of the probe changed from dark to bright under alkaline environment(p H 7-14),and the fluorescence intensity also increased gradually.The p H range from 1 to 14 showed a good linear relationship.In addition,the probe also shows high sensitivity in the actual environment detection.More importantly,this response of the probe is applicable to the p H range of wound infection(p H 5-9),which lays the foundation for the application of Ag NPs visual probes in the field of p H detection and analysis,as well as in the monitoring of wounds.