The photoelectrochemical exploration of multifunctional TiO2 mesocrystals and its enzyme-assisted biosensing application

• The photoelectrochemical performances of TiO2 mesocrystals and TiO2 single crystals were firstly compared by a series of photoelectrochmeical tests for exploring the influence of structure differences between mesocrystals and single crystals on photoelectrochemical activity.
• An elegant photoelectrochemical immune sensing platform was firstly developed by using the multifunctional TiO2 mesocrystals as excellent photoactivity materials and strong absorbers.
• In this sensing platform, carbon nanohorns with outstanding electrical conductivity was employed to support TiO2 mesocrystals and accelerate the transfer of photogenerated electrons, and horseradish peroxidase was introduced by the immune recognition reaction to enzyme-assisted in situ generation of CdS QDs.
• The multiplex amplification strategy successfully realized the ultrasensitive detection of α-fetoprotein antigen and achieved excellent analytical performances, which will offer a rational and practical consideration for fabricating new and high-performance photoelectrochemical sensing devices.

Mesocrystals, as the assemblies of crystallographically oriented nanocrystals, have single-crystal-like atom structures and scattering features but with much higher porosity than single-crystalline materials, making them promising substitutes for conventional single crystals in photoelectrochemical application. As a proof-of-concept, a series of photoelectrochemical tests were investigated to understand the influence of the differences between them on photoelectrochemical activity. Expectedly, comparing with TiO2 single crystals, TiO2 mesocrystals demonstrated higher photoelectrochemical capability, which provides unique new opportunities for materials design in the fields of solar-energy conversion and catalysis. Therefore, an elegant photoelectrochemical biosensing platform was firstly developed by virtue of carbon nanohorns with outstanding electrical conductivity support multifunctional TiO2 mesocrystals to accelerate the transfer of photogenerated electrons, and then horseradish peroxidase was introduced through the immune recognition reaction for enzyme-assisted in situ generating CdS QDs. The multiplex amplification strategy successfully achieved the ultrasensitive detection of α-fetoprotein antigen. Promisingly, the successful application of multiplex amplification strategy affords a rational and practical consideration for the fabrication of new and high-performance photoelectrochemical sensing devices.