Ionic liquid-based fluorescein colorimetric pH nanosensors

Abstract

A novel pH sensitive, colorimetric ionic liquid nanosensor based on phosphonium salts of fluorescein is reported. Herein, fluorescein salts of various stoichiometries were synthesized by use of a trihexyltetradecylphosphonium cation [TTP]+ in combination with dianionic [FL]2− and monoanionic [FL]− fluorescein. Nanomaterials derived from these two compounds yielded contrasting colorimetric responses in neutral and acidic environments. Variations in fluorescence spectra as a function of pH were also observed. Examination of TEM and DLS data revealed significant expansion in the diameter of [TTP]2[FL] nanodroplets in acidic environments of variable pHs. A similar trend was also observed for [TTP][FL] nanoparticles. The pH dependent colorimetric and other optical properties of these nanomaterials are attributed to alterations in molecular orientations and stacking as suggested by measuring the absorption, fluorescence, and zeta potential. Since the pH is an important indicator for many diseases, including cancer, these nanosensors are considered to be potential candidates for biomedical applications.

Characterization of Silver NanoparticleIn SituSynthesis on Porous Sericin Gel for Antibacterial Application

“…Silver nanoparticle is a regular and effective antibacterial material, which has shown a broad spectrum of antibacterial activity against fungus, viruses, and Gram-positive and Gram-negative bacteria [11][12][13]. With the development of nanotechnology, numerous nanomaterials with multifarious particular characteristics have been developed [14][15][16][17][18]. Recently, the immobilization of fibroin fiber with nanomaterials for multifunctional textiles has been developed [19,20].…”

Different Approaches to Develop Nanosensors for Diagnosis of Diseases

“…on polymers [186] or AuNPs modified with protein antigens [187] were also reported. An ionic liquid nanosensor for colorimetric pH detection based on phosphonium salt was reported by Das et al [188] This fluorescent salt was prepared by combining trihexyltetradecylphosphonium cation [TTP] + with monoanionic [FL] − and dianionic [FL] 2− fluorescein, yielding contrast colorimetric responses in acidic and neutral conditions. [188]…”

Ionic liquid crosslinkers for chiral imprinted nanoGUMBOS

“…ILs show interesting physical and chemical properties such as low volatility, chemical stability, and high conductivity [1], [3]; and can be tailored by molecular design of either the anionic or cationic component for task-specific functions [4], [5]. An emerging class of solid phase materials based on tunable ionic liquid chemistry, collectively referred to as GUMBOS (group of uniform materials based on organic salts), has been demonstrated as capable of forming nanoparticles (nanoGUMBOS) with magnetic, fluorescent, pH sensitive, and anticancer properties [6][7][8][9][10][11][12][13][14][15]. To combine one or more of these properties into nanoparticle based theranostic agents, incorporation of a molecular recognition element using the method of molecular imprinting was investigated for formation of nanoGUMBOS molecularly imprinted polymers (referred to as NGMIPs) [16], [17].…”