Life Sciences

The unique, size-tunable optical properties, in combination with the ease of surface modification of quantum dots (QDs) can be well employed in various life-sciences applications, like diagnosis and therapy. These applications can be classified into two types:

1. In vitro and ex-vivo diagnostics: An array of QDs emitting in multiple colors, spanning the visible and near infra-red (NIR) region of the spectrum, can be synthesized by simple variation of their diameter.Since these QDs have a broad absorption spectra and narrow emission spectra, all these multicolored QDs can be simultaneously excited using a single laser source. Their surfaces can be suitably modified for conjugation with a whole range of bioactive molecules, such as proteins/peptides and nucleic acids. These properties, coupled with their excellent photostability, makes them ideal optical probes for multiplexed detection of various physiological and pathological biomarkers from simple analysis of body fluids (e.g. blood, urine, saliva, etc.) or environmental specimens (e.g. river water). Traditional bioanalytical techniques such as ELISA, microarrays, western blots, quantitative PCRs, flow cytometry, etc. can be used for such QD based biomarker detection. The use of QD based probes would allow the fabrication of portable handheld diagnostic devices that can be used in the field.
   
   
   
2. In vivo imaging and therapy: QDs can also be used in vivo for targeted delivery specifically to diseased sites such as cancer. For these applications, the surfaces of the QDs have to be suitably modified for conjugation with a variety of biomolecules, such as:
   1. inert polymers like polyethyleneglycol (PEG) which would prevent their capture and degradation by the natural defense system of the body
   2. biorecognition molecules such as monoclonal antibodies which would target them specifically to diseased sites
   3. other diagnostic and/or therapeutic molecules that would enable advanced in vivo diagnosis and/or therapy using these nanoprobes.

   The NIR emitting QDs are particularly suited for this purpose as NIR light have the maximum penetration through biological specimens and tissues, and this would allow non-invasive optical imaging of even deep sitting organs/tissues such as tumors The co-incorporation of diagnostic and therapeutic probes would allow the non-invasive monitoring of the therapeutic progression in real-time. Although QDs are not yet approved by the US Food and drug Administration (FDA) for human use, they will likely gain approval in the near future as their ultra-small size (diameter below 10 nm) would allow their excretion from the body through urinary/fecal routes.

NanoAxis synthesizes various multicolored (visible to NIR emitting) cadmium based (AxiCad) QDs with unique double layering (CdSe/CdS/ZnS) which would ensure their high photostability and reproducibility in terms of life-sciences applications. Their surfaces will contain reactive amino groups that would facilitate their conjugation with a variety of biomolecules such as proteins, peptides, antibodies, nucleic acids, PEG molecules, and therapeutic molecules such as chemotherapeutic drugs and short-interfering (si) RNA. Thus, AxiCad QDs are ideally suited for all kinds of life-science related applications.