[Frontiers in Bioscience E3, 1013-1024, June 1, 2011]

Development of semiconductor nanomaterial whole cell imaging sensor on glass slides

Hengyi Xu1,2, Zoraida Pascual Aguilar2, Hua Wei1, Andrew Wang2

1State Key Laboratory of Food Science and Technology, Jiangxi-OAI Joint research institute, Nanchang University, 235 Nanjing Donglu, Nanchang 330047, China, 2Ocean NanoTech LLC, 2143 Worth Lane, Springdale AR 72764, USA


1. Abstract
2. Introduction
3. Materials and methods
3.1. Chemicals and reagents
3.2. Surface modification and bioconjugation of QDs with antibodies
3.3. Characterization of QDs and QD-antibody conjugates
3.4. Cell culture
3.5. Surface modification of the glass slide used as the capture surface
3.6. Solid phase quantum dot-based whole cell imaging sensor
3.7. Optimization of the sensing system
3.8. Microscopy of the QD-based whole cell sensor
4. Results and discussion
4.1. Characterization of QDs and QD-antibody conjugates
4.2. Optimization and blocking of non-specific signals
4.3. Optimization of the 20Ab~QD concentration
4.4. Capture and detection of whole cells with 20Ab~QD conjugates
5. Conclusion
6. Acknowledgments
7. References


We report the development of a highly specific semiconductor quantum dots (QDs)-based whole cell imaging sensor that offer rapid, reproducible, accurate, and long term cell imaging system on silanized microscope glass slides. The QD-based imaging sensor involved capture of whole cells with QD labeled highly specific antibodies against over expressed cell membrane proteins. The QDs were first modified with a polymer coating to generate carboxyl groups on the surface. Using the carboxylated QDs, antibodies were covalent conjugated using carbodiimide chemistry to form 20Ab~QD that were used to capture whole cell. The SK-BR3 cell line was used as a model analyte in the sandwich type assay consisting of 10Ab + SK-BR3 + Ab' + 20Ab~QD. The assay was immobilized on an antibody modified silanized microscope slide that was subsequently mounted on a fluorescence microscope for detection. The results indicated that the QD based imaging sensor exhibited brighter signals compared with organic dye Texas red. The QD-based whole cell imaging sensor was visible under the microscope even after one week without fixation.