Synthesis on aggregation of colloidal solutions of ICG-active silica nanoparticles and their application in in‐vivo fluorescence imaging

• Published in: Materials chemistry and physics 2018-12, Vol.220, p.201-207
• Main Authors: Shindo, Yuta, Inose, Tomoya, Kubota, Yohsuke, Oikawa, Takahiro, Tokunaga, Masayuki, Kamei, Takashi, Gonda, Kohsuke, Kobayashi, Yoshio
• Format: Article
• Language: English
• Subjects: Agglomeration; Aqueous solutions; Cations; Chemical synthesis; Colloids; Ethanol; Fluorescence; Fluorescent dyes; Fluorescent marker; Indocyanine green; Nanoparticles; Organic chemistry; Silica; Silicon dioxide; Sodium hydroxide; Sol-gel; Sol-gel processes
• ISSN: 0254-0584; 1879-3312
• DOI: 10.1016/j.matchemphys.2018.08.073

This study reports two findings. The first is a method for preparing a colloidal solution of silica (SiO2) nanoparticles activated with fluorescent dye or fluorescent dye-active SiO2 nanoparticles. Preparation of a colloid solution of spherical SiO2 nanoparticles with an average size of 109.4 ± 8.6 nm was performed using the sol-gel method at 35 °C using 0.2 M tetraethylorthosilicate, 25 M H2O, and 0.01 M NaOH in ethanol. Two kinds of cationic chemicals (poly-diallyldimethylammonium chloride (PDADMAC) and (3-aminopropyl) triethoxysilane (APES) were examined for surface-modification or surface-cationization of the SiO2 nanoparticles (SiO2/PDADMAC and SiO2/APES). To activate the SiO2 nanoparticles with fluorescent dye, indocyanine green (ICG) molecules were fixed on the surface-modified SiO2 nanoparticles by mixing ICG dissolved in albumin aqueous solution and the surface-modified SiO2 nanoparticle colloid solution (SiO2/PDADMAC/ICG and SiO2/APES/ICG) through electrostatic aggregation. The second finding is the verification of the fluorescence ability of the ICG-active SiO2 nanoparticle colloid solutions. Both the ICG-active SiO2 nanoparticle colloid solutions exerted fluorescence even at high ICG concentrations. Mouse tissues could be imaged by injecting the ICG-immobilized SiO2 nanoparticle colloid solution into the tail vein of the mouse and measuring the emitted fluorescence intensity. Pulmonary embolism was avoided in the SiO2/APES/ICG particle colloid solution-injected group, in which the particles reached the tissues more efficiently than in the SiO2/PDADMAC/ICG nanoparticles-injected group. [Display omitted] •Spherical SiO2 nanoparticles were fabricated using the sol-gel method.•The SiO2 nanoparticles were surface-modified with polymer or silane-coupling agent.•Indocyanine green (ICG) was electrostatically fixed on the modified particle surfaces.•Mouse tissues could be imaged by the injection of the ICG-active particles.