Preparation Of Pillar[n]arenes Functionalized Nanomaterials And Their Application In Electrochemical Detection

With the development of nanoscience,nanomaterials have broad application prospects in the fields of electrochemical sensing,photo/electrocatalysis,and biomedicine.The surface structure and the state of nanomaterials can be modified by physical or chemical methods.Pillar[n]arenes are a kind of cyclic oligomers composed of methylene bridged hydroquinone units,which have symmetric rigid cavities.Because of their simple synthesis,easy modification,adjustable size and variable conformation,pillar[n]arenes have received considerable attention from researchers.The surface modification of nanomaterials with pillar[n]arenes can improve the dispersion and interfacial compatibility of nanomaterials,and may bring host-guest properties to nanomaterials,illustrating obvious advantages in the fields of optical/electrical detection,catalysis,energy storage,biosensor and imaging.This paper focuses on the surface modification of nanomaterials,including noble metals,carbon materials and metal oxides/sulfides.Pillar[n]arenes containing different groups can combine with nanomaterials through covalent or non-covalent interaction to construct a series of nanocomposites with specific functions and properties.The prepared nanocomposites not only have the host-guest recognition ability of pillar[n]arenes,but also show the inherent physical-chemical properties of nanomaterials.In this paper,the nanocomposites were applied to electrochemical detection of organic molecules,DNA and antigen,and the function of pillar[n]arenes in the sensing platform was also explored.The main research contents of this paper are as follows:The first part:the application of pillar[n]arenes functionalized nanomaterials in electrochemical detection of small molecules.（1）WP6-Au/MoSe2 nanomaterials were prepared by reducing HAuCl4 onto the surface of MoSe2 nanoflowers using water-soluble pillar[6]arenes（WP6）as stabilizer,and they were characterized by TEM,XRD,FTIR and XPS.The WP6-Au/MoSe2 modified glassy carbon electrode（GCE）not only possesses good conductivity,but also shows unique host-guest recognition ability.WP6-Au/MoSe2/GCE can effectively and accurately distinguish the mixture of ascorbic acid（AA）,dopamine（DA）and uric acid（UA）,and then achieve the simultaneous detection of AA,DA and UA.（2）Pt NPs were successfully reduced on the tube wall of MWCNTs by chemical reduction method to obtain Pt/MWCNTs nanocomposite.Pt/MWCNTs-PP6were prepared by theπ-πstacking interaction between Pt/MWCNTs and PP6,and they were characterized by TEM XRD,FTIR and XRS.The nanocomposites have excellent conductivity and unique host-guest recognition ability.Pt/MWCNTs-PP6/GCE can effectively and accurately distinguish the mixture of catechol（HQ）,resorcinol（RS）and hydroquinone（CC）,and then achieve the simultaneous detection of HQ,CC and RS.The second part:the application of pillar[n]arenes functionalized nanomaterials in electrochemical detection of HBV-DNA.（1）PdNPs were reduced on the surface of graphene using WP5 as the stabilizer,and the obtained WP5-Pd/RGO materials were characterized by TEM,XRD,and XPS.Benefiting from the interaction between host and guest,MB labeled DNA probe can be captured onto the WP5-Pd/RGO modified electrode surface.The recognition reaction between WP5 and MB was verified by UV and FL experiments.The strategy of DNA immobilization based on pillar[n]arenes can not only enhance the probe immobilization efficiency,but also maintain an appropriate distance between DNA molecules.HP5-Au/CoS were prepared by reducing AuNPs onto the surface of CoS hollow nanobox using hydroxyl pillar[5]arene（HP5）as stabilizer.The sandwich sensor for the detection of HBV-DNA was constructed based on DNA complementary base pairing rules,using WP5-Pd/RGO as electrode materials and HP5-Au/CoS as signal materials.The current comes from the reduction of H2O₂,and the proposed sensing platform can sensitively and accurately detect HBV-DNA in the range of 1 fmol/L to 1 nmol/L.（2）the mono-dispersed WP5-AgNPs was prepared using WP5as stabilizer.The WP5-AgNPs can self-assemble into WP5-Ag/PEHA two-dimensional supramolecular network structure under the induction of PEHA molecules,which was characterized by TEM,UV and XPS.HP5-Au/MWCNTs nanomaterials were prepared by reducing AuNPs onto the surface of MWCNTs using HP5 as reducing agent and stabilizer.Due to the host-guest interaction between HP5-AuNPs and RhB,the RhB labeled probe DNA was firmly immobilized on HP5-Au/MWCNTs modified electrode surface.The sandwich sensor for the detection of HBV-DNA was fabricated using WP5-Ag/PEHA as signal materials and HP5-Au/MWCNTs as electrode materials.The current comes from the dissolution current of AgNPs,and the proposed sensing platform can sensitively and accurately detect HBV-DNA in the range of 0.1 fmol/L to 0.1 nmol/L.The third part:the application of pillar[n]arenes functionalized nanomaterials in electrochemical detection of antigen.（1）PdNPs were reduced on the surface of MoS₂nanosheets using chemical reduction method to obtain Pd/MoS₂ nanocomposite.Subsequently,WP5-Pd/MoS₂ nanomaterials were prepared throughπ-πinteraction between Pd/MoS₂ and WP5,which were verified by TEM,XRD,FTIR and XRS.Thionine（Thi）can be captured on the surface of WP5-Pd/MoS₂ through charge transfer interaction.The sandwich immunosensing platform for the detection of squamous cell carcinoma antigen（SCCA）was constructed using Thi@WP5-Pd/MoS₂ as signal materials and Au/TiO₂ as electrode materials.The current comes from the oxidation reaction of Thi,and the proposed sensing platform can sensitively and accurately detect SCCA in the range of 0.001～10 ng/mL.（2）In alkaline conditions,2HP5-AuNPs were obtained by the reaction of 2HP5 with HAuCl4 at room temperature.The 2HP5-AuNPs were characterized by TEM,and the formation mechanism of AuNPs was studied by FTIR,XPS and ¹³C NMR measurements.The 2HP5-Au-Pd/MnO₂ nanomaterials were obtained by the integration of Pd/MnO₂ and 2HP5-AuNPs,which were characterized by TEM,element mapping,XRD,and XPS.Benefiting from the host-guest interaction,toluidine blue（TB）can be captured on the surface of 2HP5-Au-Pd/MnO₂.The sandwich immunosensor for the detection of cTnI was constructed using electrodeposited nanogold as electrode materials and TB@2HP5-Au-Pd/MnO₂ as signal materials.The current comes from the oxidation reaction of TB,and the proposed sensing platform can sensitively and accurately detect cTnI in the range of 0.005～20 ng/mL.