Multifunctional Silica Nanoparticles Modified via Silylated‐Decaborate Precursors

Abstract

A new class of multifunctional silica nanoparticles carrying boron clusters (10-vertex closo-decaborate) and incorporating luminescent centers (fluorescein) has been developed as potential probes/carriers for potential application in boron neutron capture therapy (BNCT). These silica nanoparticles were chargedin situwith silylated-fluorescein fluorophoresviathe Stöber method and their surface was further functionalized with decaborate-triethoxysilane precursors. The resulting decaborate dye-doped silica nanoparticles were characterized by TEM, solid state NMR, DLS, nitrogen sorption, elemental analysis, and fluorescence spectroscopy.

Recent Achievements on Functionalization within closo‐Decahydrodecaborate [B10H10]2− Clusters

“…The boratosilane precursors were also anchored on the surfaces of silica nanoparticles (SNPs) for the sole purpose of exploiting their vital role as theranostics agents. The SNPs were engineered as tracking agents and delivery agents of the decaborate cluster; they were covalently charged with luminescent centers as silylated isothiocyanate fluorescein compounds C 30 H 34 N 2 O 8 SSi and Tri‐nitrato‐tris[3‐(triethoxysilyl)‐propyl diphenylphosphine oxide]Eu III compound (as the simple entrapment of fluorescein and EU III in the framework suffered from several drawbacks, one of which is feeble luminescence efficiency due to hydroxyl quenching originating from the silanol groups) [74] . More recently, a new approach for the preparation of boron‐containing siloxanes has been reported, this approach details the reaction of hydroxy derivatives of closo‐decaborate anion [B 10 H 10‐n (OH) n ] 2− (n=1, 2) with dihalosilanes SiR 2 Cl 2 (R=CH 3 , t‐ C 4 H 9 , C 6 H 5 ) [73,75] …”

“…The SNPs were engineered as tracking agents and delivery agents of the decaborate cluster; they were covalently charged with luminescent centers as silylated isothiocyanate fluorescein compounds C 30 H 34 N 2 O 8 SSi and Tri-nitrato-tris [3-(triethoxysilyl)-propyl diphenylphosphine oxide]Eu III compound (as the simple entrapment of fluorescein and EU III in the framework suffered from several drawbacks, one of which is feeble luminescence efficiency due to hydroxyl quenching originating from the silanol groups). [74] More recently, a new approach for the preparation of boroncontaining siloxanes has been reported, this approach details the reaction of hydroxy derivatives of closo-decaborate anion [B 10 H 10-n (OH) n ] 2À (n = 1, 2) with dihalosilanes SiR 2 Cl 2 (R = CH 3 , t-C 4 H 9 , C 6 H 5 ). [73,75] In results yet to be published, di-substituted silane precursors were successfully synthetized starting from decaborate derivatives [B 10 H 9 O(CH 2 ) 4 ] À and [B 10 H 8 (O(CH 2 ) 4 ) 2 ] with Xpropyltriethoxysilanes where X is a nucleophilic terminal substituent as the À NH 2 .…”

Synthesis of Derivatives of closo-Dodecaborate Anion Based on Amino Acid Esters

“…Boron cluster anions are widely used as components of photovoltaic devices [1][2][3][4][5][6], catalysts [7,8], biosensors [9,10], and molecular magnets [11,12]. One of the most important areas of application of closo-borate anions is boron neutron capture therapy of malignant tumors [13][14][15][16][17][18].…”

Encapsulation of Chaotropic closo‐Decahydrodecaborate Clusters Within Cyclodextrins: Synthesis, Solution Studies, and DFT Calculations

“…This property thus makes the studies of the borane derivatives of a great interest, especially the carboranes, and the derivatives of the [B 12 H 12 ] 2– and of the [B 10 H 10 ] 2– clusters. The latter offers the possibility of various selective functionalizations leading for example to closo ‐decaborate‐triethoxysilane precursors which can be coordinated to luminescent dye doped silica nanoparticles, hence facilitating the tracing of the closo ‐decaborate drug pathway in BNCT , …”