Ans. d. Nanocrystals exhibit a narrow difference between their excitation and emission peak spectra (Ref: http://www.semrock.com/fluorescence-imaging-with-quantum-dot-nanocrystals. aspx ; style="font-size: 1.04761904761905em; font-family: Times New Roman, Times, serif">; Article ID=2375"Semiconductor nanocrystals were prepared for use as fluorescent probes in biological staining and diagnostics. Compared with conventional fluorophores, the nanocrystals have a narrow, tunable, symmetric emission spectrum and are photochemically stable. The advantages of the broad, continuous excitation spectrum were demonstrated in a dualemission, single-excitation labeling experiment on mouse fibroblasts. These nanocrystal probes are thus complementary and in some cases may be superior to existing fluorophores". - Science 25 September 1998: Vol 281 No. 5385 pp2013-2016After much searching we could get some information on the nanocrystals and nanotechnology which could be easy to understand. Most of the material available was quite complicated and beyond our scope.Nanotechnology is the manipulation of matter on an atomic and molecular scale. By convention, nanotechnology is taken as the scale range 1 to 100 nm following the definition used by the National Nanotechnology in the US.One nanometer is one billionth, or 10-9 of a meter. To give a sense of measurement a DNA double-helix has a diameter around 2 nm and the smallest cellular life-forms, the bacteria of the genus Mycoplasma, are around 200 nm in length.Nanocrystals, also called Quantum dots, are inorganic crystals that exhibit very strong fluorescent emissions. These materials are considered semiconductors and range from one to fifty nanometers in diameter.These semiconductor nanocrystals are remarkably durable.The desired behavior and transmission directly correlates to their size. To change the emitted wavelength, the crystal is grown larger or smaller. Their electronic and optical properties can be controlled by this method. For example to change the emission from one visible wavelength to another simply use a larger or smaller grown crystal.The nanocrystal size controls a widely tunable absorption band resultign in widely tunable emission spectra. This tunability combined with the optical stability of nanocrystals and the great chemical flexibility in the nanocrystal growth have resulted in the widespread nanocrystal applications in use today. They have been a mainstay as fluorescent markers in biological and medical research for years. As such, they are usually incorporated into polystyrene beads, mixed into a solution and then incorporated into the biological system.NanotechnologyNanomedicine is the medical application of nanotechnology.http://en.wikipedia.org/wiki/Nanomedicine - cite_note-Nanomed1-1 Nanomedicine ranges from the medical applications of nanomaterials, to nanoelectronic biosensors, and even possible future applications of molecular nanotechnology.The biological and medical research communities have exploited the unique properties of nanomaterials for various applications (e.g., contrast agents for cell imaging and therapeutics for treating cancer).Thus far, the integration of nanomaterials with biology has led to the development of diagnostic devices, contrast agents, analytical tools, physical therapy applications, and drug delivery vehicles.Abraxane, approved by the U.S. Food and Drug Administration (FDA) to treat breast cancer and non-small- cell lung cancer (NSCLC), is the nanoparticle albumin bound paclitaxel.