Design, Preparation And Application Of Polydiacetylene-based Functional Materials

Sensing materials response toward external stimuli by giving another physical signalthat can be easily detected or directly observed by us. With the fast development of scienceand technology, sensing technology has wide applications in national defense strategicplanning, industrial production and civil living. There is no doubt that sensing technologyhas become an indispensible part in the modern society.Polydiacetylene-based materials can be used as a typical class of sensing materials.Polydiacetylene can be synthesized by polymerizing diacetylene monomers under UVirradiation. Usually it is blue, and it rapidly changes its color from blue to red uponenvironmental stimuli, such as heat, organic solvents and inorganic anions. Specifically,polydiacetylene is found to be electrical current-responsive recently. Blue polydiacetyleneis nonfluorescent, but red polydiacetylene has fluorescent emission. Polydiacetylene hasthus been widely developed as chromatic and fluorescent sensors.A great deal of research about graphene has been carried out in the field ofchemistry, physics and biology. One of the excellent properties of graphene is the highconductivity. Many scientists used graphene as conductive materials with great success.Fluorescent microspheres are functional microspheres that stable in structure andmorphology, highly efficient in emission. They are widely used in clinical diagnosis, drugcarriers and biochip technology. Seeking more convenient methods to prepare differenttype of fluorescent microspheres is of great significance in both science research andindustrial application.Based on what we discussed above, here we choose polydiacetylene the main material.Based on the fact that polydiacetytlene changes its color from blue to red when electricalcurrent passing through, we combined polydiacetylene with conductive graphene toproduce electrical current sensor. In addition, we prepared fluorescent microspheres byattaching fluorescent polydiacetylene vesicles onto the polymer microspheres. Finally, bluevesicle changes its color from blue to red when meeting some inorganic anions. Based onthis phenomenon, we fabricated Ca2+sensing microspheres.1) Preparation of polydiacetylene-based electrochromatic composites Aiming to develop pH-paper-like current sensing materials, we prepared irreversibleelectrochromic PDA-PMMA/graphene composites. The composites exhibited an excellentlinear relationship between critical responsive currents and the amount of graphene in thesystem. In these composites, PDA acted as the electrochromic material and graphene as theconductive matrix. The presence of PMMA not only ensured mechanical performance butalso made the color change more obvious to be observed by the naked eye.2) Preparation of polydiacetylene-based fluorescent microspheresFluorescent microspheres are prepared by attaching self-assembled polydiacetylene(PDA) vehicles with carboxyl side groups onto the substrate amino-modifiedpoly(glycidylmethacrylate)(APGMA) microspheres. The characterizations by SEM,confocal microscopy and flow cytometry demonstrated that the final resultingmicrospheres are highly uniform both in size (with a diameter of5μm) and influorescence emission (coefficient of variance <3%). In addition, there are evenlydistributed pores with an average size of20.6nm on the spheres. TheBrunauer-Emmett-Teller (BET) surface area for these spheres is114m2/g. These spheresare found to have good thermal stability and photostability, as well as good resistanceagainst water washing. FITC modified BSA are easily loaded onto these fluorescentmicrospheres because of the existence of–COOH in PDA vesices. All these characteristicspossessed by these APGMA-PDA spheres allow them to be directly used as carriers ofbiomolecules in the lab-on-a-chip immunoassay systems.3) Preparation of polydiacetylene-based Ca2+sensing microspheresIn our work2), we prepared microspheres with–COOH and amine groups on itssurface. This kind of microspheres respond smartly and specifically to Ca2+. With theconcentration of Ca2+grows, these microspheres change their color from blue to redgradually. UV spectrμm and fluorescent images give corresponding results. This allowsfor further development of Ca2+sensors in biochemistry and pollutant detection.