A　ternary　hybrid　was　developed　through　interaction　between　a　hierarchical-ordered　TiO2　and　a　thiol　group　that　was　obtained　by　in　situ　chemical　polymerization　of　L-cysteine　on　the　carbon　nanohorn　(CNH)　superstructure　modified　electrode.　Herein,　unique-ordered　TiO2　superstructures　with　quasi-octahedral　shape　that　possess　high　crystallinity,　high　porosity,　oriented　subunit　alignment,　very　large　specific　surface　area,　and　superior　photocatalytic　activity　were　first　introduced　as　a　photosensitizer　element　in　the　photoelectrochemical　determination.　Additionally,　the　assembly　of　hierarchical-structured　CNHs　was　used　to　provide　an　excellent　electron-transport　matrix　to　capture　and　transport　an　electron　from　excited　anatase　to　the　electrode　rapidly,　hampering　the　electron-hole　recombination　effectively,　resulting　in　improved　photoelectrochemical　response　and　higher　photocatalytic　activity　in　the　visible　light　region.　Owing　to　the　dependence　of　the　photocurrent　signal　on　the　concentration　of　electron　donor,　4-methylimidozal,　which　can　act　as　a　photogenerated　hole　scavenger,　an　exquisite　photoelectrochemical　sensor　was　successfully　fabricated　with　a　wide　linear　range　from　1　X　10(-4)　to　1　x　10(-10)　M,　and　the　detection　limit　was　down　to　30　pM.　The　low　applied　potential　of　0.2　V　was　beneficial　to　the　elimination　of　interference　from　other　reductive　species　that　coexisted　in　the　real　samples.　More　importantly,　the　mesocrystal　was　first　introduced　in　the　fabricating　of　a　biosensor,　which　not　only　opens　up　a　new　avenue　for　biosensors　manufactured　based　on　mesocrystal　materials　but　also　provides　beneficial　lessons　in　the　research　fields　ranging　from　solar　cells　to　photocatalysis.