The innovation engine for new materials

Nathaniel Conrad

Major: 

Physics

University: 

University of California Santa Barbara

Mentor(s): 

Lourdes Velazquez
Chang-Young Park

Faculty Sponsor(s): 

Deborah K. Fygenson

Faculty Sponsor's Department(s): 

Physics

Project Title: 

Mechanical properties of variable valence DNA nanostar ultra-structures

Project Description: 

The ability to encode for genetic information is not the only important and useful property of DNA. The specific base pairing of DNA strands can be manipulated to create complex nano-structures which can aggregate together to form self-assembled networks resulting in thermo-reversible DNA gels. Most biological systems composed of polymers can internally manipulate their self-assembled ultra-structures in order to respond to external stimuli. Consequently, it is of interest to study the ultra-structure of these polymeric gels and understand how the underlying structural components determine their physical properties. The reversible base-pairing of double stranded DNA offers the ability to mimic and design polymeric gels, while also being much more resistant to degradation and small temperature changes. We have constructed variable valence DNA nanostar structures that are designed to mimic structural proteins with multiple unbiased binding domains in order to promote the self-assembly of large nanostar networks. The elasticity and viscosity of the DNA gels were probed using passive microrheology. Preliminary results indicate that the mechanical properties of DNA nanostar gels are affected by factors like the initial DNA and ion concentrations. Future experiments will investigate how the length of binding sites and valence of the nanostar affect the stiffness of the resulting gels. The ability to tune the mechanical features of DNA nanostar gels by varying internal and external factors illustrates the versatility of DNA as a structural material.