Physical and practical limits of a biomolecular control system using nanoparticles and electromagnetic field irradiation

[摘要] Many nanometer length scale engineering applications of mechanics and biology including computation, sensing, self-assembly, transport, and molecular machine design take advantage of natural biomolecular machinery. Further development of these technologies requires direct, external biomolecular control. This thesis proposes a simple control technique: a biomolecular on/o;; activity switch in which metallic nanoparticles (NPs) are conjugated to target biomolecules and irradiated with an electromagnetic field. Due to their unique physical properties, the NPs specifically absorb the field;;s energy. They convert the energy to heat, and then they transport it to the conjugated target biomolecules. The heat affects a change in the targeted biomolecules, selectively actuating their activity. This thesis is on the mechanisms by which both ultrafast pulsed laser irradiation and radio frequency alternating magnetic fields (RFMFs) can be used as energy sources for the proposed biomolecular activity switch. The thesis reports on the quantification of a fs-pulsed laser triggered release mechanism that actuates activity of the molecules released from NPs. The release mechanism is governed by NP surface chemistry. The operating window for the critical parameters governing release including NP properties and laser fluence is defined. The thesis also reports on transmission pump-probe experiments that show the thermal interface conductance (G) of NPs is critical to nanoscale thermal transport, and that G is a strong function of the NP;;s surface chemistry. The thesis concludes that an ultrafast pulsed laser actuated biomolecular activity switch is feasible if the critical parameters are carefully controlled. However, experimental studies revealed that using RFMFs in this biomolecular activity switching technique is not feasible. These results are validated by theoretical and analytical studies of nanoscale heat generation and transport in the system. The results presented in this thesis have implications on the design of the biomolecular activity switch, and many of the results are also applicable to other nanoscale thermal applications including hyperthermia cancer treatments and triggered drug delivery techniques.

[发布机构] Massachusetts Institute of Technology