The effect of all-trans retinoic acid (ATRA) on the expression of vascular endothelial growth factor (VEGF) and VEGF receptors of human colon cancer LoVo cell line

All-trans retinoic acid (ATRA) was found to inhibit cell growth, induce differentiation and enhance apoptosis in a variety of malignant solid tumors. Retinoic acid is effective in inhibiting the expression of vascular endothelial growth factor (VEGF) in some cancer. In this study, we investigated the effect of ATRA on the expression of VEGF and its receptors in LoVo cells, and its possible mechanisms. LoVo cells were treated with ATRA at different concentrations for different time, and with exogenous recombinant human VEGF165 or VEGF165 + ATRA. Cell viability was measured by microtitration (MTT) assay. Cell cycle and apoptosis were evaluated by flow cytometry (FCM). The expression of VEGF in LoVo cells were detected by ELISA technique and Western blot, and its receptors by flow cytometry. ATRA greatly inhibited the proliferation of LoVo cells in dose- and time-dependent manners; inhibition rate of the cells decreased significantly after treatment with ATRA. ATRA could dose-dependently block the VEGF165-induced cell growth. FCM results show that ATRA induced apoptosis of LoVo cells with concomitant decrease of expressed VEGF and its receptors. The mechanism involved in down regulation of VEGF and its receptors may be related to apoptosis. ATRA could also disturb the stimulating effect of VEGF165 on the growth of LoVo cells. These results suggest that ATRA can delay growth of LoVo cells by inhibiting the paracrine and autocrine pathways.Key words: All-trans retinoic acid, LoVo cells, vascular endothelial growth factor, vascular endothelial growth factor (VEGF) receptors

Rapid and Facile Synthesis of Gold Trisoctahedrons for Surface-Enhanced Raman Spectroscopy and Refractive Index Sensing

Au trisoctahedrons (TOHs) with sharp tips and high-index facets have exceptional properties for diverse applications, such as plasmon-enhanced spectroscopies, catalysis, sensing, and biomedicine. However, the synthesis of Au TOHs remains challenging, and most reported synthetic methods are time-consuming or involve complex steps, hindering the exploration of their potential applications. Herein, we present a facile and fast approach to prepare Au TOHs with high uniformity and good control over the final size and shape, all within less than 10 min of synthesis, for surface-enhanced Raman spectroscopy (SERS) and refractive index sensing. The size of the Au TOHs can be easily tailored over a wide range, from 39 to 268 nm, allowing a tuning of the plasmon resonance at wavelengths from visible to near-infrared regions. The exposed facets of the Au TOHs can also be varied by controlling the growth temperatures. The wide tunability of size and exposed facets of Au TOHs can greatly broaden the range of their applications. We have also encapsulated Au TOHs with zeolite imidazolate framework (ZIF-8), obtaining core–shell hybrid structures. With the ability to tune Au TOH size, we further assessed their SERS performances in function of their size by detecting 2-NaT in solution, exhibiting enhancement factors of the order of 105 with higher values when the LSPR is blue-shifted from the laser excitation wavelength. Au TOHs have been also compared for refractive index sensing applications against Au nanospheres, revealing Au TOHs as better candidates. Overall, this facile and fast method for synthesizing Au TOHs with tunable size and exposed facets simplifies the path toward the exploration of properties and applications of this highly symmetrical and high-index nanostructure

Rapid and Facile Synthesis of Gold Trisoctahedrons for Surface-Enhanced Raman Spectroscopy and Refractive Index Sensing

Au trisoctahedrons (TOHs) with sharp tips and high-index facets have exceptional properties for diverse applications, such as plasmon-enhanced spectroscopies, catalysis, sensing, and biomedicine. However, the synthesis of Au TOHs remains challenging, and most reported synthetic methods are time-consuming or involve complex steps, hindering the exploration of their potential applications. Herein, we present a facile and fast approach to prepare Au TOHs with high uniformity and good control over the final size and shape, all within less than 10 min of synthesis, for surface-enhanced Raman spectroscopy (SERS) and refractive index sensing. The size of the Au TOHs can be easily tailored over a wide range, from 39 to 268 nm, allowing a tuning of the plasmon resonance at wavelengths from visible to near-infrared regions. The exposed facets of the Au TOHs can also be varied by controlling the growth temperatures. The wide tunability of size and exposed facets of Au TOHs can greatly broaden the range of their applications. We have also encapsulated Au TOHs with zeolite imidazolate framework (ZIF-8), obtaining core–shell hybrid structures. With the ability to tune Au TOH size, we further assessed their SERS performances in function of their size by detecting 2-NaT in solution, exhibiting enhancement factors of the order of 105 with higher values when the LSPR is blue-shifted from the laser excitation wavelength. Au TOHs have been also compared for refractive index sensing applications against Au nanospheres, revealing Au TOHs as better candidates. Overall, this facile and fast method for synthesizing Au TOHs with tunable size and exposed facets simplifies the path toward the exploration of properties and applications of this highly symmetrical and high-index nanostructure

Rapid and Facile Synthesis of Gold Trisoctahedrons for Surface-Enhanced Raman Spectroscopy and Refractive Index Sensing

Au trisoctahedrons (TOHs) with sharp tips and high-index facets have exceptional properties for diverse applications, such as plasmon-enhanced spectroscopies, catalysis, sensing, and biomedicine. However, the synthesis of Au TOHs remains challenging, and most reported synthetic methods are time-consuming or involve complex steps, hindering the exploration of their potential applications. Herein, we present a facile and fast approach to prepare Au TOHs with high uniformity and good control over the final size and shape, all within less than 10 min of synthesis, for surface-enhanced Raman spectroscopy (SERS) and refractive index sensing. The size of the Au TOHs can be easily tailored over a wide range, from 39 to 268 nm, allowing a tuning of the plasmon resonance at wavelengths from visible to near-infrared regions. The exposed facets of the Au TOHs can also be varied by controlling the growth temperatures. The wide tunability of size and exposed facets of Au TOHs can greatly broaden the range of their applications. We have also encapsulated Au TOHs with zeolite imidazolate framework (ZIF-8), obtaining core–shell hybrid structures. With the ability to tune Au TOH size, we further assessed their SERS performances in function of their size by detecting 2-NaT in solution, exhibiting enhancement factors of the order of 105 with higher values when the LSPR is blue-shifted from the laser excitation wavelength. Au TOHs have been also compared for refractive index sensing applications against Au nanospheres, revealing Au TOHs as better candidates. Overall, this facile and fast method for synthesizing Au TOHs with tunable size and exposed facets simplifies the path toward the exploration of properties and applications of this highly symmetrical and high-index nanostructure