We report herein the controlled synthetic strategy for Prussian blue nanoparticles (PBNPs) formation justifying the role of functional alkoxysilanes, [2-(3,4-Epoxycyclohexyl)ethyl]trimethoxysilane (EETMSi) in the presence of tetrahydrofuran hydroperoxide (THF-HPO) with following major findings: (i) significant change in nanogeometry from 40 to 8 nm by addition of EETMSi and (ii) allowed fabrication of PBNPs encapsulated silica-alginate beads. As made nanoparticles were characterized by UV-Vis spectroscopy, TEM, FT-IR, and SEM. Size dependent electrochemical behavior of three different PBNPs i.e. PBNPs-1 (26 nm), PBNPs-2 (17 nm) and PBNPs-3 (8 nm) was recorded based on cyclic voltammetry. Apart from unprecedented size-dependent properties, as made PBNPs-3 display excellent peroxidase mimetic activity with Km value to the order of similar to 0.9 mM. In addition, EETMSi also allows to cast Prussian blue film and simultaneously enable the formation of silica-alginate beads with controlled pores size perfectly suitable for encapsulating these nanoparticles which allocate selective electrochemical oxidation of Pyrogallol (Py) at 0.3 V vs. Ag/AgCl. (C) 2018 Elsevier Ltd. All rights reserved.