Functionalized graphene oxide quantum dot–PVA hydrogel: a colorimetric sensor for Fe²⁺, Co²⁺and Cu²⁺ions

Abstract

Functionalized graphene oxide quantum dots (GOQDs)-poly(vinyl alcohol) (PVA) hybrid hydrogels were prepared using a simple, facile and cost-effective strategy. GOQDs bearing different surface functional groups were introduced as the cross-linking agent into the PVA matrix thereby resulting in gelation. The four different types of hybrid hydrogels were prepared using graphene oxide, reduced graphene oxide, ester functionalized graphene oxide and amine functionalized GOQDs as cross-linking agents. It was observed that the hybrid hydrogel prepared with amine functionalized GOQDs was the most stable. The potential applicability of using this solid sensing platform has been subsequently explored in an easy, simple, effective and sensitive method for optical detection of M(2+) (Fe(2+), Co(2+) and Cu(2+)) in aqueous media involving colorimetric detection. Amine functionalized GOQDs-PVA hybrid hydrogel when put into the corresponding solution of Fe(2+), Co(2+) and Cu(2+) renders brown, orange and blue coloration respectively of the solution detecting the presence of Fe(2+), Co(2+) and Cu(2+) ions in the solution. The minimum detection limit observed was 1 × 10(-7) M using UV-visible spectroscopy. Further, the applicability of the sensing material was also tested for a mixture of co-existing ions in solution to demonstrate the practical applicability of the system. Insight into the probable mechanistic pathway involved in the detection process is also being discussed.

Hydrogel Based Biosensors for In Vitro Diagnostics of Biochemicals, Proteins, and Genes

“…The constructed hydrogel network structure may disintegrate by being exposed to specific target analytes in a dose‐dependent manner, since the binding affinities of aptamers to their target analytes are much stronger than that of simple hybridization affinities of aptamers. The deformation of the hydrogel network can be easily detected with naked eyes or by using various colorimetric or fluorescence agents such as gold nanoparticles, silver, iodine, quantum dots, and fluorescent dyes …”

Manganese(ii) enhanced fluorescent nitrogen-doped graphene quantum dots: a facile and efficient synthesis and their applications for bioimaging and detection of Hg2+ ions

“…18,19 However, there are a series of problems for the direct carbonization of citric acid to face, such as complicated preparation process, harsh reaction conditions (such as strong acid/ alkali using), accurate pH control and tedious postprocessing, which may lead to great restrictions for the further biomedical applications of QDs. [20][21][22] To extend and improve the physical and chemical properties of GQDs, different modication methods have been applied, including surface functional groups modication, 23 heteroatoms doping 24,25 and formation of composite. 26,27 For example, the ways of functionalization with surface groups and heteroatoms doping (such as N,S) may signicantly transform the optical properties, quantum yields, chemical activities and electronics structure of GQDs, 28,29 which would provide interesting luminescent properties, such as pH-dependent and excitation-dependent photoluminescence (PL) behaviors.…”

Design, Bioanalytical, and Biomedical Applications of Aptamer-Based Hydrogels

“…Because the binding affinities of aptamers to their target analytes are much stronger than that of simple hybridization, the network structure may deform or disintegrate when the specific target analytes are presented. The deformation of the aptamer-based hydrogel network can be easily detected with naked eyes or various colorimetric or fluorescence agents including, silver, gold nanoparticles, iodine, fluorescent dyes, and quantum dots (83,(100)(101)(102)(103)(104)(105)(106)(107). The constructed hydrogel biosensor may achieve visual detection easily.…”