| Based on the high light-scattering power of resonance light scattering (RLS) particles, the applications of RLS particles as highly fluorescent analogs and their use as tracer labels in clinical and biological applications, ultrasensitive immuno- and DNA probe assays combined with microscopy and imaging techniques have being addressed more and more interests. It has proved that the use of RLS particles as labels can obtain the significant increase in sensitivity over fluorescent labels. In this contribution, based on the common RLS method, we established a new resonance light scattering imaging technique and can observe the features of individual scatterers. The method has been applied to sensitive assay of biological macromolecules and medicine molecules by imaging and detecting the single light scattering species. The paper consists of four sections.(1) The spectral properties of hydrolyzed Cr(III) oligomers were investigated and their interaction with nucleic acids was also investigated by measurement of enhancement of resonance light scattering (RLS) signals. Hydrolyzed Cr(III) oligomers have characteristic absorption peaks of 415 nm and 580 nm. It was observed that Cr(III) oligomers displayed a fluorescent property with maximum excitation and emission wavelengths at 225 nm and 350 nm, respectively. In the acid medium, the hydrolyzed Cr(III) oligomers can interact with DNA, resulting in strong enhanced RLS signals characterized at 299.0 nm. Based on this, the interaction of inorganic polymer reagent with biological macromolecules was discussed, and the sensitive method of nucleic acids was developed.(2) In acidic medium, J-aggregation of α.β.γ.δ-tetrakis(p-sulfophenyl)porphine(TPPS4) and α,β,γ,δ-tetrakis(5-sulfothienyl)prophine [T(5-ST)P] in the presence of proteins occurs, resulting in strong RLS signals characterized at 490 nm and 469.0 nm, respectively. Under the excitation of 488 nm light beam of argon ion laser source, RLS signals of single protein-induced .J-aggregation species could be observed at the right angle to the incident beam with a common microscope and the images could be digitally imaged by a cooled charge-coupled device (CCD). Data analysis showed that the counts of the aggregation species imaged in detection focus plane are proportional to the concentration of proteins. The sensitive method of proteins was established accordingly. The results of determination for three human blood serum samples were identical to the reference values according to the method of Coomassie Brilliant Blue (CBB G- 250).(3) In neutral medium, the combination of heparin with α,β,γ,δ-tetra(4-trimethyl aminonium phenyl)prophine (TAPP) by electrostatic and hydrophobic interaction force can result in strong RLS signals at 430 nm. The single aggregation species of heparin with TAPP could be illuminated by a 441.6 nm laser source, and the light scattering signals of single species could be observed with a common microscope. Data analysis for the images of aggregation species by a digitalized CCD camera showed that the counts of aggregate species in the detection focus plane are proportional to the concentration of heparin. The method was successfully applied to detect heparin content in heparin sodium injection samples.(4) A light scattering imaging method combined with microfluidic channel device was developed and applied to the determination of trace amount of berberine based on the high light scattering power of single light scattering particles. In neutral medium, a single aggregation species of berberine with a, p, y, 8-tetrakis(p-sulfophenyl)prophine (TPPS4) inside a microflow channel can be illuminated by a 488 nm laser beam, which is guided through a prism to incident the aggregation species. The light scattering signals of single species could be observed with a common microscope, and the images could be captured by a digital CCD...
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