Achilefu's Group

Within the NHLBI-PEN Project, the Achilefu group will synthesize high affinity polypeptides for targeting and monitoring integrins, commonly associated with tumor-stimulated angiogenesis and metastasis. The detection of integrins and their expression is a viable approach in early detection of wide range of cancer. In a typical approach developed in a lab, a recognition molecule is coupled with a fluorescent probe and then used for in-vivo studies of tumors. In the proposed approach the recognition peptides will be conjugated to nanoparticles: quantum dots and gold nanoparticles.

Quantum dots are nanoscale semiconductor crystals with exceptional optical properties: such as photobleaching resistance, extremely high fluorescence quantum yield, independence of the emission from the excitation wavelength and narrow emission spectrum. Coupling of peptides to different color quantum dots will generate fluorescent nanoparticles with highly specific, in terms of wavelength, emission, thus allowing multicolored imaging.

In another approach the peptides will be conjugated to gold nanoparticles. Aggregated gold molecules conjugated to fluorophores are known to be efficient but distance-dependent quenchers of fluorescence. We plan to employ this phenomenon by conjugating a recognition peptide to both, a gold nanoparticle and to a fluorescent probe. The system will also have a cleavage domain, such as a photocleavable linker. Upon cleavage, the fluorescence will be restored.

The Optical Lab operates four organic chemistry rooms; two biochemistry/molecular biology rooms and molecular imaging room with total footage of 3000 sq. ft. lab space. Conjugation of nanoparticles to peptides and other small molecules will be conducted in organic chemistry lab in Barnard Bldg #6601 equipped with 5 hoods with vacuum, air and water lines, a peptide synthesizer, analytical HPLC with UV-Vis detector (Waters), semi-preparative HPLC (Beckman Coulter) for peptides purification, lyophilizer and other equipment. Chemical and optical characterization of the peptides and nanoconjugates will be held in East Bldg, #203 outfitted with LC-MS with ESI and chemical ionization probes (Shimadzu), UV-Vis (Beckman) and fluorescence spectrophotometers (Jobin Yvon). Additional capabilities for analysis and synthesis comprise 300 MHz NMR (GE), microplate reader Synergy (Bio-Tek), high pressure Parr reactor etc. Cell labeling experiments will be conducted in biochemistry labs in Barnard Bldg. #6605 and East Bldg. #1152. The labs are equipped with 3 biological hoods, CO2 incubators, freezers and centrifuges. Imaging tools are located in East Bldg ##1140, 1142, 1152 and include fluorescent and confocal microscope (Olympus), multimodal (X-Ray and optical) small animal image station (Kodak), small animal time domain diffuse optical tomograph (GE) and home made planar optical imager.