Ling Dong

Determination of γ-globulin at nanogram levels by its enhancement effect on the resonance light scattering of functionalized HgS nanoparticles

A novel assay of gamma-globulin (gamma-IgG) with a sensitivity at the nanogram level is proposed based on the measurement of enhanced resonance light-scattering (RLS) signals resulting from the interaction of functionalized nano-HgS with gamma-globulin. At pH 5.03, the RLS signals of functionalized nano-HgS were greatly enhanced by gamma-globulin in the region of 200-700nm characterized by the peak around 362nm. Linear relationship can be established between the enhanced RLS intensity and gamma-globulin concentration in the range of 10-140ngml(-1). The limit of detection is 2.71ngml(-1). Based on this, a new direct quantitative determination method for gamma-globulin in blood serum samples without separation of human serum albumin (HSA) is established. The contents of gamma-IgG in blood serum samples were determined with recovery of 95.7-102.5% and R.S.D. of 1.6-2.4%. This method is proved to be very sensitive, rapid, simple and tolerance of most interfering substances.

Application of Organic Nanoparticles as Fluorescence Probe in the Determination of Nucleic Acids

Abstract Organic fluorescent nanoparticles (NPs) have been successfully synthesized by reprecipitation method under ultrasonic irradiation. In comparison with single organic fluorophores, these NPs are brighter, photo‐chemically stable, and water‐soluble. At acidic medium, the fluorescence of NPs is 60 times strong as that of 1‐pyrenemethylamine. They also have high room temperature fluorescence quantum yields (∼20%) and twice long fluorescence lifetime (∼0.2 µsec) as that of single organic fluorophores. A fluorescence method has been developed for rapid determination of DNA with these organic NPs as a fluorescence probe, based on the fluorescence quenching of NPs in the presence of DNA. Maximum fluorescence quenching is produced at pH 2.0 with maximum excitation and emission wavelengths of 238 and 400 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4–10.5 µg mL−1 for calf thymus DNA (ct‐DNA) and 0.8–20.0 µg mL−1 for fish sperm DNA (fs‐DNA). The corresponding detection limit is 0.019 µg mL−1 for ct‐DNA and 0.022 µg mL−1 for fs‐DNA. The relative standard deviation of six replicate measurements is 1.3–2.2%. The method is simple, rapid, and sensitive. The recovery and relative standard deviation are very satisfactory.

Direct quantification of γ-globulin in human blood serum by resonance light scattering techniques without separation of human serum albumin

We describe the preparation and characterization of functionalized nano-PbS. The functionalized nanoparticles are water-soluble. Reaction of mercaptoacetic acid functionalized nano-PbS with γ-globulin (γ-IgG) results in an enhanced resonance light scattering (RLS) at 385 nm. Based on this, a new direct quantitative method for γ-globulin in blood serum samples without separation of human serum albumin is established. Under optimal conditions, the enhanced RLS intensity is in proportion to the γ-IgG concentration in the range 10–500 ng ml−1. The 3σ limit of detection is 2.75 ng ml−1. The contents of γ-IgG in blood serum samples were determined with a recovery of 97–104% and R.S.D. of 1.5–2.1% (n=6). This method proved to be very sensitive, rapid, simple and tolerant of most interfering substances.

Novel luminescent nanoparticles for DNA detection

Highly luminescent LaF(3):Ce(3+)/Tb(3+) nanocrystals were successfully prepared and surface functionalized via Layer-by-Layer technology. These as-prepared nanocrystals are highly resistant to photobleaching and pretty dispersible in aqueous solution. Due to the efficient luminescence quenching of the nanocrystals by nucleic acids, a facile fluorescence quenching method was developed for the detection of trace amount of nucleic acids. Under optimal conditions, the fluorescence intensity was proportional to the DNA concentration over the range of 0.60-25.0microgmL(-1) for calf thymus DNA (ct-DNA) and 0.60-30.0microgmL(-1) for herring sperm DNA (hs-DNA), respectively. The corresponding detection limit is 0.21microgmL(-1) for ct-DNA and 0.31microgmL(-1) for hs-DNA, respectively. The results indicated that the reported method is simple and rapid with wide linear range. Also, the recovery and relative standard deviation of this method are reasonable and satisfactory.