Abstract
We demonstrate porous silicon biological probes as a stable and non-toxic alternative to organic dyes or cadmium-containing quantum dots for imaging and sensing applications. The fluorescent silicon quantum dots which are embedded on the porous silicon surface are passivated with carboxyl-terminated ligands through stable Si-C covalent bonds. The porous silicon bio-probes have shown photoluminescence quantum yield around 50% under near-UV excitation, with high photochemical and thermal stability. The bio-probes can be efficiently conjugated with antibodies, which is confirmed by a standard enzyme-linked immunosorbent assay (ELISA) method.
Highlights
Fluorescent probes or labels are extensively used in a variety of biological investigations, such as in vivo cellular imaging [1], in vitro protein sensing [2] or even intraoperative tumor visualization [3]
We demonstrate porous silicon biological probes as a stable and non-toxic alternative to organic dyes or cadmium-containing quantum dots for imaging and sensing applications
The fluorescent silicon quantum dots which are embedded on the porous silicon surface are passivated with carboxyl-terminated ligands through stable Si–C covalent bonds
Summary
Fluorescent probes or labels are extensively used in a variety of biological investigations, such as in vivo cellular imaging [1], in vitro protein sensing [2] or even intraoperative tumor visualization [3]. The traditional fluorophores are made of organic dyes, such as fluorescein and cyanines, which have good enough photoluminescence quantum yield (PLQY) and wellestablished protocols for bio-conjugation, purification and optical characterization Their low photochemical and thermal stability sometimes limit their effectiveness in high illumination flux applications [4]. Semiconductor quantum dots, such as CdS, CdSe, CdTe quantum dots, have emerged as promising substitutes for the organic dyes They possess unique optical properties which make them stand out in some biological applications, including size-dependent photoluminescence (PL), high PLQY, narrow emission spectra (full-width at half-maximum, FWHM < 50 nm), broad excitation spectra, large stokes shift and high resistance to photobleaching [5]. The loading of antibodies on the bio-probe surfaces was verified by an enzyme-linked immunosorbent assay (ELISA) method
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