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Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Design and Fabrication of Fiber-Optic Nanoprobes for Optical Sensing | Zhang et al. Nanoscale Res Lett 2011 6 18 http www.nanoscalereslett.eom content 6 1 18 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Design and Fabrication of Fiber-Optic Nanoprobes for Optical Sensing Yan Zhang1 2 Anuj Dhawan1 2 Tuan Vo-Dinh1 2 3 Abstract This paper describes the design and fabrication of fiber-optic nanoprobes developed for optical detection in single living cells. It is critical to fabricate probes with well-controlled nanoapertures for optimized spatial resolution and optical transmission. The detection sensitivity of fiber-optic nanoprobe depends mainly on the extremely small excitation volume that is determined by the aperture sizes and penetration depths. We investigate the angle dependence of the aperture in shadow evaporation of the metal coating onto the tip wall. It was found that nanoaperture diameters of approximately 50 nm can be achieved using a 25 tilt angle. On the other hand the aperture size is sensitive to the subtle change of the metal evaporation angle and could be blocked by irregular metal grains. Through focused ion beam FIB milling optical nanoprobes with well-defined aperture size as small as 200 nm can be obtained. Finally we illustrate the use of the nanoprobes by detecting a fluorescent species benzo a pyrene tetrol BPT in single living cells. A quantitative estimation of the numbers of BPT molecules detected using fiber-optic nanoprobes for BPT solutions shows that the limit of detection was approximately 100 molecules. Introduction The emergence of nanotechnology opens new horizons for nanosensors and nanoprobes that are suitable for intracellular measurements. Nanosensors provide critical information for monitoring biomolecular processes within a single living cell thus could provide great advances in biomedical research and clinical applications. Fiber-optic nanosensors with nanoscale dimensions are capable of sensing intracellular intercellular physiological and biological parameters
