Any bit of matter in a liquid is pummelled by forces from the surrounding bath of liquid molecules. So a minute particle in a fluid is always wandering off and after a while finds itself at a random location far from where it started. Fascinating things could be done if nanoscopic particles or molecular-scale entities - nearly a million times smaller than the width of a strand of hair - could be made to stay at the same location for long spells of time. One could measure the physical properties and behaviour of single molecules in solution as well as use single nanoparticles to perform useful functions such as data storage. We have recently developed the ability to trap single biological molecules in solution without the application of external fields. Our trap depends sensitively on the electrical charge carried by the molecule. Within the scope of this proposal we will develop new methods to study the behaviour of single trapped molecules in solution and measure their physical properties such as size, electrical charge, and three-dimensional structure. The ability to perform high-sensitivity, high-precision measurements on single molecules will not only have novel and important fundamental impact but also foster the development of ultra-sensitive biomedical detection and analytics at the nanometer scale.