Second-harmonic generation(SHG)microscopy is a recently developed nonlinear optical imaging modality for imaging tissue structures with submicron resolution and is a potent tool for visualizing pathological effects of diseases.In this letter,we present our investigation on the influence of van Gieson's(VG) alcoholic picrofuchsin staining on SHG in typeⅠcollagen(from tendon-rich C57BL/6).Multi-channel imaging and spectra analysis show that the strong SHG signal produced in fresh collagen typeⅠfiber has been greatly suppressed after VG staining,which indicates that staining may induce the structural or characteristic changes of SHG-dependent crystal formed by collagen constituents,such as glycine,proline, and hydroxyproline.
This paper first demonstrates second-harmonic generation(SHG) in the intact cell nucleus,which acts as an optical indicator of DNA malignancy in prostate glandular epithelial cells.Within a scanning region of 2.7 μm×2.7 μm in cell nuclei,SHG signals produced from benign prostatic hyperplasia(BPH) and prostate carcinoma(PC) tissues(mouse model C57BL/6) have been investigated.Statistical analyses(t test) of a total of 405 measurements(204 nuclei from BPH and 201 nuclei from PC) show that SHG signals from BPH and PC have a distinct difference(p < 0.05),suggesting a potential optical method of revealing very early malignancy in prostate glandular epithelial cells based upon induced biochemical and/or biophysical modifications in DNA.
