Regulating interparticle interactions to control the spatio temporal assembly of gold nanoparticles

Abstract

Self Assembly is nature 8217 s preferred 8216 zero waste 8217 means of creating animate matter It typically involves the realization of functional materials from individual building blocks without the need for any external or human intervention Researchers are focused on understanding the principles underlying the self assembly process so as to form purposeful and useful structures despite the lack of human intervention In light of this the aim of my thesis is to study the effects of finely tuned interparticle interactions in governing the outcomes of both spatial as well as temporal self assembly processes We demonstrate that a control over interparticle interactions can be successfully translated to create systems with fascinating degrees of complexity This thesis contains a summary of our efforts that show how finely tuned interparticle interactions can a improve existing nanoparticle NP properties b show the emergence of inherently absent properties and c mimic complex 8216 life like 8217 behaviour Here the property of our choice was aggregation mediated identification of heavy metal ions while the behaviour of our choice was the formation of transiently stable self assembled structures With these specific goals in mind in Chapter 2 we designed heterogeneously charged gold nanoparticles AuNPs where strengths of different interparticle interactions could be regulated by simply changing the ratio of oppositely charged ligands on the NP surface We used these NP systems to balance different attractive and repulsive interparticle interactions and reveal an unprecedented phenomenon of controlled aggregation These NP systems could reversibly 8216 arrest 8217 toxic ions like lead Pb2 and cadmium Cd2 through the formation of controlled aggregates making them a recyclable trapping and scavenging system A key advantage of the present system is the simplicity with which the mixed Self Assembled Monolayer m SAM on the NPs could be tuned to trap and scavenge different triggers of interest like Pb2 Cd2 H and newline newline