Low-Potential Photoelectrochemical Biosensing Using Porphyrin-Functionalized TiO₂ Nanoparticles

Abstract

A novel photoelectrochemical biosensing platform for the detection of biomolecules at relatively low applied potentials was constructed using porphyrin-functionalized TiO₂ nanoparticles. The functional TiO₂ nanoparticles were prepared by dentate binding of TiO₂ with sulfonic groups of water-soluble [meso-tetrakis(4-sulfonatophenyl)porphyrin] iron(III) monochloride (FeTPPS) and characterized by transmission electron microscopy; contact angle measurement; and Raman, X-ray photoelectron, and ultraviolet-visible absorption spectroscopies. The functional nanoparticles showed good dispersion in water and on indium tin oxide (ITO) surface. The resulting FeTPPS-TiO₂-modified ITO electrode showed a photocurrent response at +0.2 V to a light excitation at 380 nm, which could be further sensitized through an oxidation process of biomolecules by the hole-injected FeTPPS. Using glutathione as a model, a methodology for sensitive photoelectrochemical biosensing at low potential was thus developed. Under optimal conditions, the proposed photoelectrochemical method could detect glutathione ranging from 0.05 to 2.4 mmol L⁻¹ with a detection limit of 0.03 mmol L⁻¹ at a signal-to-noise ratio of 3. The photoelectrochemical biosensor had an excellent specificity against anticancer drugs and could be successfully applied to the detection of reduced glutathione in gluthion injection, showing a promising application in photoelectrochemical biosensing.

Photoelectrochemistry of Free‐Base‐Porphyrin‐Functionalized Zinc Oxide Nanoparticles and Their Applications in Biosensing

“…Some photoelectrochemical materials such as TiO 2 , SnO 2 , CdS, and CdSe semiconductor nanoparticles have been used for this purpose. [8][9][10][11][12][13][14] For instance, a photoelectrochemical immunosensor has been designed for the detection of a-Synuclein using Au-doped TiO 2 nanotube arrays. [8] A highly sensitive photoelectrochemical sensor based on a SnO 2 -nanoparticle-modified indium tin oxide (ITO) electrode has been developed for the detection of adenosine triphosphate (ATP) in the extracts of cancer cells.…”

“…[11] Our previous work assembled an iron-porphyrin-containing sulfonic group on TiO 2 nanoparticles to develop a photoelectrochemical biosensing method for glutathione detection. [14] Porphyrins are the mimics of many enzymes. Metalloporphyrins such as iron-porphyrin, cobalt-porphyrin, and manganese-porphyrin exhibited good electrocatalysis toward many small molecules related to life processes.…”

“…[19][20][21][22] Moreover, a porphyrin-containing carboxylic or sulfonic groups can spontaneously adsorb onto ZnO nanoparticles by bridging, ester-like, or bidentate binding. [2,14,[23][24][25] The carboxylic-group-containing porphyrins possess a higher solar-energy conversion efficiency than sulfonic-group-containing porphyrins in dye-sensitized solar cells due to their stronger absorption coefficient. [2][3][4][5]25] Therefore, this work used carboxylic-group-containing free-base porphyrins to functionalize ZnO nanoparticles for sensitizing the photoelectrochemical efficiency of ZnO nanoparticles, which produced a universal photoelectrochemical biosensing platform.…”

Nanoparticles in biomedical applications

“…TiO 2 nanoparticles have many unique properties such as biocompatibility, chemical stability and optical properties [173]. It is because of these properties that there has been a recent increase in the use of TiO 2 nanoparticles in biomedical applications such as drug delivery [174][175][176][177][178][179], bioimaging [175], photoablation therapy [180][181][182][183][184][185] and biosensors [186,187], which will be discussed further in Section 4. Other metal oxide nanoparticles that are gaining interest in biomedical applications are cerium oxide (CeO 2 ) nanoparticles or nanoceria.…”

“…TiO 2 has many unique features such as good biocompatibility, low toxicity, chemical stability and photocatalytic properties which makes it an attractive material for use in the biomedical industry. Due to its unique properties, lots of research has been carried out on using TiO 2 nanoparticles in different biomedical applications such as drug delivery, PDT, cell imaging, biosensors and genetic engineering [173][174][175][176][177][178][179][180][181][182][183][184][185][186][187]. In this review, we will discuss the use of TiO 2 nanoparticles in targeted drug delivery and PDT.…”