Using the effect of the fluorescence enhancement in close proximity to metal nanostructures, we have been able to demonstrate ultrasensitive immunoassays suitable for the detection of biomarkers. Silver fractal-like structures have been grown by electrochemical reduction of silver on the surface of glass slides. A model immunoassay was performed on the slide surface with rabbit IgG (antigen) noncovalently immobilized on the slide, and rhodamine red-X-labeled antirabbit IgG conjugate was subsequently bound to the immobilized antigen. The fluorescence signal was measured from the glass-fractal's surface using a confocal microscope, and the images were compared to the images from the same surface not coated with fractals. Our results showed significant enhancement (more than 100-fold) of the signal detected on fractals compared to bare glass. We thus demonstrate that such fractal-like structures can assist in improving the signals from assays used in medical diagnostics, especially those for analytes with molecular weight under 100 kDa.

Mammalian embryo implantation involves a series of complex interactions between maternal and embryonic cells. Uterine polypeptide growth factors may play critical roles in these cell interactions. Basic fibroblast growth factor (basic FGF) is a member of a family of growth factors. This growth factor may be potentially important for the process of embryo implantation because it (a) is stored within the extracellular matrix and is thus easily available during embryo invasion, (b) is a potent modulator of cell proliferation and differentiation and (c) stimulates angiogenesis. The immunolocalization of basic FGF in the uterus during the peri-implantation period of pregnancy is presented in this study. Uterine tissue samples were obtained on days 6-9 of pregnancy with day 1 of pregnancy being the day of a vaginal copulatory plug. Uterine samples were fixed in Bouin's fluid for no longer than 18 h. Following fixation and paraffin embedding, sections were exposed to primary antisera made in rabbits against either (a) human recombinant basic FGF or (b) 1-24 synthetic fragment of bovine basic FGF. The primary antibody was followed by biotinylated goat anti-rabbit IgG and a biotin-avidin-peroxidase complex. There were no differences in the immunolocalization of basic FGF using either source of primary antibody. Our results demonstrated both temporal and spatial changes in the localization of immunoreactive basic FGF within the implantation chamber during days 6-9 of pregnancy. Inter-implantation sites resembled the non-pregnant uterus with basic FGF present in extracellular matrices including basal laminae. On day 6 of pregnancy, decidual cells within the primary decidual zone lacked both intracellular and pericellular basic FGF while non-decidualized uterine stroma resembled inter-implantation sites. By days 7-8 of pregnancy, the secondary decidual zone had formed and was characterized by the distinct pericellular localization of basic FGF around individual decidual cells. By day 9 of pregnancy, the mesometrial region was forming and contained cords of decidual cells and a labyrinth of maternal blood vessels. The decidual cells contained diffuse intracellular basic FGF. Trophoblast cells were devoid of basic FGF at all times examined. These results indicate that basic FGF is present within the implantation chamber on days 6-9 of pregnancy and may be involved in the decidual cell response, trophoblast cell invasion and angiogenesis.

Basic fibroblast growth factor is a biologically active peptide with a strong affinity for heparin. This growth factor has been previously shown to be mitogenic for a variety of mesoderm and neuroectoderm-derived cells. The immunohistochemical localization of basic FGF within mouse growing and atretic ovarian follicles is presented in the study. Ovarian tissue samples were obtained either (a) randomly from mice housed in a controlled light environment or (b) following the administration of exogenous gonadotropins to stimulate follicle development. Ovarian samples were fixed in Bouin's fluid for no longer than 18 h. Following fixation and paraffin embedding, sections were exposed to a primary antibody made in rabbits against either (a) human recombinant basic FGF or (b) the 1-24 synthetic fragment of bovine basic FGF. The primary antibody was followed by biotinylated goat anti-rabbit IgG and a biotin-avidin-peroxidase complex. There were no differences in the immunolocalization of basic FGF using either source of primary antibody or between randomly obtained ovarian samples and those obtained from mice given exogenous gonadotropins. Basic FGF was immunolocalized in follicle basal laminae and was also closely associated with individual follicle cells during all stages of ovarian follicle development. Basic FGF was absent in the theca interna, oocyte cytoplasm, zona pellucida and follicle fluid of normal growing follicles. Individual corpora luteal cells were surrounded by basic FGF but lacked cytoplasmic staining. Atretic follicles exhibited staining patterns similar to their respective stage of follicle development. However, when present, follicle fluid within atretic follicles was strongly positive for basic FGF. These results indicate that basic FGF may be an important factor involved in intraovarian control mechanisms.