Centered on localized gene delivery, Mao's research proposed biodegradable polymer coatings for sequential DNA release from implantable devices. This was built on her PhD research on the multilayer films. In 2016, she and her team pioneered the idea of using retrograde transport proteins to specifically deliver drugs for treating respiratory issues linked to spinal cord injury. In related research, she collaborated with Harry Goshgarian and Abdulghani Sankari to advance nanotherapeutics by integrating retrograde transport proteins, adenosine receptor antagonists, and nanoparticle carriers. Furthermore, she proposed a new technique for delivering drugs specifically to the central nervous system (CNS) using nanoparticles that are chemically attached to neural tract tracer proteins and can be transported along specific neural pathways, allowing them to bypass the blood–brain barrier and target the CNS directly. Mao used human embryonic stem cells (hESCs) for assessing nanotoxicology, specifically, the effect of nanoparticle size on the viability, pluripotency, neuronal differentiation, and DNA methylation of hESCs. Her work revealed a type of gold nanoparticles to be highly toxic and demonstrated the potential of hESCs in predicting nanotoxicity.