Modification of Amorphous Mesoporous Zirconia Nanoparticles with Bisphosphonic Acids: A Straightforward Approach for Tailoring the Surface Properties of the Nanoparticles

Abstract

The use of readily prepared bisphosphonic acids obtained in few steps through a thio‐Michael addition of commercially available thiols on tetraethyl vinylidenebisphosphonate enables the straightforward surface modification of amorphous mesoporous zirconia nanoparticles. Simple stirring of the zirconia nanoparticles in a buffered aqueous solution of the proper bisphosphonic acid leads to the surface functionalization of the nanoparticles with different kinds of functional groups, charge and hydrophobic properties. Formation of both chemisorbed and physisorbed layers of the bisphosphonic acid take place, observing after extensive washing a grafting density of 1.1 molecules/nm2 with negligible release in neutral or acidic pH conditions, demonstrating stronger loading compared to monophosphonate derivatives. The modified nanoparticles were characterized by IR, XPS, ζ‐potential analysis to investigate the loading of the bisphosphonic acid, FE‐SEM to investigate the size and morphologies of the nanoparticles and 31P and 1H MAS NMR to investigate the coordination motif of the phosphonate units on the surface. All these analytical techniques demonstrated the strong affinity of the bisphosphonic moiety for the Zr(IV) metal centers. The functionalization with bisphosphonic acids represents a straightforward covalent approach for tailoring the superficial properties of zirconia nanoparticles, much straightforward compared the classic use of trisalkoxysilane or trichlorosilane reagents typically employed for the functionalization of silica and metal oxide nanoparticles. Extension of the use of bisphosphonates to other metal oxide nanoparticles is advisable.

Nanotechnology in the Fabrication of Advanced Paints and Coatings: Dispersion and Stabilization Mechanisms for Enhanced Performance

“… Surface‐functionalization of the zirconia NPs with phosphonic acid by applying a post modification approach. Reproduced with permission from Ref [113] . (Copyright 2021 WILEY‐VCH).…”

“…This is particularly relevant in the stabilization of MOs such as ZrO 2 , TiO 2 , Al 2 O 3 , Fe 3 O 4 and ITO. The surface modification of ZrO 2 NPs was successfully done by using biophosphonic acid coupling agents (Figure 20) by pplying a post modification approach [113] …”

“…The surface modification of ZrO 2 NPs was successfully done by using biophosphonic acid coupling agents (Figure 20) by pplying a post modification approach. [113] Carboxylic Acids: Carboxylic acids (RÀ COOH) can bind to the surface of MOs NPs through metal-carboxylate bonds. The carboxylate group (COO À ) can coordinate with metal ions on the NPs surface, providing stability and preventing aggregation.…”

Present and Future of ZrO2 Nanostructure as Reservoir for Drug Loading and Release

“…The surface of ZrO2 nanostructures can be functionalized with various functional groups, such as amino, carboxylic, and thiol groups, which can be used for drug conjugation or electrostatic interactions with drugs (Figure 1) [45,46]. The functional groups used in the functionalization of ZrO2 nanostructures provide versatility in conjugating other molecules, improving stability [23], targeted delivery, solubility, controlled release, and surface modification, thereby expanding their applications in various fields, including medicine, biotechnology, and materials science [47][48][49].…”

Surface modification of zirconia by various modifiers to investigate its reinforcing efficiency toward nitrile rubber

“…[18][19][20] A plenty of reports are available on surface modification of zirconia that has been studied from different viewpoints. This includes a variety of surface modifier, namely, Organosilane: bis(triethoxysilylpropyl) tetrasulfide (TESPT), [19] methacryloxypropyltrimethoxysilane (MPS), [21,22] 3-(amino propyl) trimethoxysilane (APTES) [23,24] ; Surfactants: sodium dodecyl sulphate (SDS), [25,26] cetyltrimethyl ammonium bromide (CTAB), [27,28] lauryl amine hydrochloride [29] ; organic additives: 2-hydroxyethyl methacrylate (HEMA), [30] ethyl 3,4-dihydroxy cinnamate (EDHC), allylmalonic acid (AMA), trimethylolpropane trimethacrylate (TMPMA), [31] carboxylic acid, [32] bis-phosphonic acid, [33] glucose and fructose. [34,35] However, high cost, processing complexity and elevated processing temperature, needed for efficient surface modification, are some major drawbacks to limit their practical applicability in large scale.…”