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Protease-based Cancer Screening Using Nanoliter Samples

IB-2240

APPLICATIONS OF TECHNOLOGY:

  • Early stage screening of cancers via detection of proteases and proteolytic activity in fluid or biopsy samples
  • Prostate cancer detection, and possibly the detection of other protease-related cancers such as breast, colon, kidney, skin, stomach, ovary, and lung cancer

ADVANTAGES:

  • Nanoliter sample volumes
  • Reduces false positives for prostate cancer screening
  • Nanomolar sensitivity
  • Fast detection and real-time reaction monitoring
  • Easy to integrate into microfluidic systems
  • High fidelity and high signal to noise ratio Raman signal

ABSTRACT:

Berkeley Lab researchers have invented an in vitro method that enables the screening of protease-related cancers at close to the single cancer cell level, a critical advance if cancer is to be detected and targeted in its earliest stages.  The invention detects proteases and proteolytic activity with nanomolar sensitivity using nanoliter sample volumes.  Berkeley Lab scientists have successfully applied the real-time method to prostate specific antigen (PSA) detection.

Conventional prostate cancer tests that detect the presence of total prostate specific antigen (PSA) achieve subnanomolar sensitivity.  The disadvantages are that they have high false positive rates and require milliliter sample volumes. Alternative assays for the proteolytically active form of PSA, which is a more accurate tumor marker and malignancy predictor than total PSA, reduce the number of false positives because they differentiate prostate cancer patients from those with benign prostate hyperplasia.  However, these tests are seminal-fluid based assays where large samples are difficult to obtain from older patients and biopsies, and they are currently relatively insensitive at very low sample volumes. The Berkleley Lab test is sensitive enough to significantly reduce false positives using only nanoliter sample volumes.

In Berkelely Lab’s protease-based method, Fanqing Chen and colleagues have conjugated PSA-specific peptides to a core/shell nanocrescent.  The peptides are linked to Raman active tags to create Raman scattering probes.  The Raman spectral signal from the tag molecules is enhanced by the nanocrescent and the signal is monitored as the peptide is cleaved by a proteolytically active PSA molecule, disengaging the tag from the nanocrescent.  The specificity of the peptide minimizes the detection of other serine proteases and results in a high-fidelity and high signal-to-noise ratio nanoprobe.  The probes easily could be incorporated into microfluidic devices.

 

 
 
 

PSA-specific peptides are conjugated to a core/shell nanocrescent. The peptides are linked to Raman active tags. Their Raman spectral signal is enhanced by the nanocrescent and monitored as the peptide is cleaved by a proteolytically active PSA molecule, disengaging the tag from the nanocrescent. As digestion of the peptides proceeds, the tag signal disappears.

 

STATUS:

  • US Patent Application # 12/299,284 available at www.uspto.gov. Available for licensing or collaborative research.

REFERENCE NUMBER: IB-2240

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