Effect of artificial redox mediators on the photoinduced oxygen reduction by photosystem I complexes

Abstract

The peculiarities of interaction of cyanobacterial photosystem I with redox mediators 2,6-dichlorophenolindophenol (DCPIP) and N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) were investigated. The higher donor efficiency of the reduced DCPIP form was demonstrated. The oxidized form of DCPIP was shown to be an efficient electron acceptor for terminal iron-sulfur cluster of photosystem I. Likewise methyl viologen, after one-electron reduction, DCPIP transfers an electron to the molecular oxygen. These results were discussed in terms of influence of these interactions on photosystem I reactions with the molecular oxygen and natural electron acceptors.

Photosystem I Multilayers within Porous Indium Tin Oxide Cathodes Enhance Mediated Electron Transfer

“…Within the meso‐ITO, the ITO nanoparticles pack randomly and densely, forming pore sizes between 20 and 100 nm (Figures A and 2B). These mesopores are on the scale of the crystallographic PSI protein complex unit cell dimensions, approximately 12×13×19 nm . The meso‐ITO electrodes have a thickness of 4.6±1.3 μm via profilometry (Figure S3A), and the dense porous structure extends uniformly to the substrate surface, as shown in the cross‐sectional SEM (Figure C).…”

“…Many electrochemical mediators have been studied within PSI bioelectrodes to achieve high rates of MET . One particularly high‐performing mediator pair is 2,6‐dichlorophenolindophenol (DCPIP) and ascorbate (AscH) . Upon dissolution of sodium ascorbate salt into deionized water, AscH is protonated, forming ascorbic acid (AscH 2 ).…”

“…(1)] in which two electrons and two protons are transferred to DCPIP, forming DCPIPH 2 and dehydroascorbate (DHA) . DCPIPH 2 is a fast electron donor to P 700 + , making it an ideal mediator species for shuttling charge between the P 700 + reaction center and the cathode material . Herein, DCPIPH 2 is used to ensure fast electron transfer from ITO to PSI multilayers in order to study the effect of the porous ITO morphology on MET. …”

“…[4][5][6][7][8] To achieve charge transfer in PSI-based biohybrid systems, the soluble redoxactive proteins that interact with PSI in plants are replaced with electrochemical mediators and metal, semi-metal, or semiconducting electrode materials. [5][6][7][8][9][10][11][12] One limiting factor within PSI-based bioelectrodes is the slow electron transfer between PSI's reaction centers and the electrode materials, which ultimately limits the produced photocurrent. [6][7][8] Electron transfer in PSI bioelectrodes can be categorized into two broad groups: direct electron transfer (DET) and mediated electron transfer (MET).…”

“…[37,38] One particularly high-performing mediator pair is 2,6-dichlorophenolindophenol (DCPIP) and ascorbate (AscH). [10,37] Upon dissolution of sodium ascorbate salt into deionized water, AscH is protonated, forming ascorbic acid (AscH 2 ). AscH 2 then undergoes a heterogenous reaction [Eq.…”