Recent progress in the field of semiconductor nanocrystals or Quantum Dots (QDs) has seen them find wider
acceptance as a tool in biomedical research labs. As produced, high quality QDs, synthesized by high temperature
organometallic synthesis, are coated with a hydrophobic ligand. Therefore, they must be further processed to be
soluble in water and to be made biocompatible. To accomplish this, the QDs are generally coated with a synthetic
polymer (eg. block copolymers) or the hydrophobic surface ligands exchanged with hydrophilic material (eg. thiols).
Advances in this area have enabled the QDs to experience a smooth transition from being simple inorganic
fluorophores to being smart sensors, which can identify specific cell marker proteins and help in diagnosis of diseases
such as cancer.
In order to improve the biocompatibility and utility of the QDs, we report the development of a procedure to coat QDs
with silk fibroin, a fibrous crystalline protein extracted from Bombyx Mori silkworm. Following the coating process,
we characterize the size, quantum yield and two-photon absorption cross section of the silk coated QDs. Additionally,
the results of biocompatibility studies carried out to compare the properties of these QD-silks with conventional QDs
are presented. These natural polymer coatings on QDs could enhance the intracellular delivery and enable the use of
these nanocrystals as an imaging tool for studying subcellular machinery at the molecular level.
We report on the development of a Forster resonance energy transfer (FRET) enabled atomic force microscope (AFM)
for the study of biomechanics and mechanobiology at the cellular level. The hybrid microscopy system combines the
spatial resolution and control of the AFM with the nanoscale sensing capabilities of FRET to enable simultaneous
detection of cell mechanical responses and correlation of those responses with cellular biochemistry. Here, we show
FRET signal from donor-coated microspheres, that are attached to an AFM cantilever, to acceptor-labeled integrins in a
fixed cell system. Additionally, we demonstrate and discuss the attachment of quantum dots to silica microspheres as the