| Plasmon resonance energy transfer(PRET)is a form of resonance energy transfer which involves plasma.In PRET,noble metal nanoparticles with plasmon resonance scattering characteristics are always selected as energy donors,and chromophores such as small organic molecules and biological macromolecules are used as energy accep-tors.The chromophores must own light absorption capacity.When noble metal nano-particles are closely coupled to chromophores by resonance,as well as the plasmon resonance scattering spectra of nanoparticles overlap with the absorption spectra of chromophores,energy transfer can occur by the dipole-dipole interaction between no-ble metal nanoparticles and chromophores.This energy transfer is verified by the quenching of the plasmon resonance scattering spectra of noble metal nanoparticles and the decreased scattering signal of single particle.As a novel form of energy trans-fer,PRET has several advantages,such as high spectral resolution,high sensitivity,and good selectivity.Thus it has been widely applied in biomolecular recognition,cellular physiological status monitoring,detection of ions and molecular,light catalysis and photovoltaic system enhancement.However,due to the spectral overlap between energy donors and acceptors,it is not easy to construct a PRET system for analysis.Recently,most of PRET systems use cytochrome c or rhodamine derivatives as energy acceptors,while the energy donors are mostly gold nanospheres(Au NPs)or gold nanorods(Au NRs).Thus,there exit some problems in the application of PRET,such as the relatively single donor-acceptor pairs and the limited coupling efficiency between the energy donors and acceptors.Therefore,it is a hot issue for establishing novel PRET coupling systems to progress the application of PRET in analytical chemistry.Urchin-like gold nanoparticles(UGPs)are branched-structured nanoparticles composed of a central core and many branched tips.Compared with Au NPs and Au NRs,UGPs have higher specific surface area,stronger local electric field enhancement effect and significant plasma antenna effect.The localized surface plasmon resonance(LSPR)depends on the number of tips,length,and aspect ratio of UGPs and etc.Therefore,UGPs can have spectral tenability from the visible light region to the near-infrared region by adjusting the tip angle or length during the synthesis process.Based on this,this paper takes UGPs as the research object.Benefited from the adjust-able LSPR properties and the extremely strong local electric field enhancement effect of UGPs,novel PRET systems are established.The donors and acceptors can couple by electrostatic adsorption,and these PRET systems are further applied in analysis and detection.The specific contents are summarized as the following two aspects:(1)Plasmon resonance energy transfer between urchin-like gold nanoparti-cles and oxidized 3,3',5,5'-tetramethylbenzidine(oxTMB)was used for highly se-lective determination of acid phosphatase(ACP).Combining PRET with an enzy-matic reaction,a highly selective method for the detection of ACP was constructed.The prepared UGPs had a multi-tip structure and a large specific surface area.The LSPR characteristic scattering peak of UGPs was located at 634 nm,so it could over-lap with the absorption spectrum of oxTMB which had an absorption characteristic at652 nm.Moreover,the UGPs with negatively charged could combine with positive oxTMB by a simple electrostatic adsorption.Thus a new PRET coupling system be-tween oxTMB and UGPs was constructed,and the PRET was occurred.When the tar-get ACP was present,the enzymatic reaction product ascorbic acid(AA)could reduce oxTMB to TMB without absorption at 652 nm.The spectral mismatch between the re-duced product TMB and UGPs could effectively block the occurrence of PRET,which caused the recovery of the scattering intensity of UGPs.The results showed that the recovery of the scattering spectral intensity of UGPs was linearly related to the con-centration of ACP in the range of 0.1 to 5.0 U/L,and the detection limit was 0.076U/L.(2)Plasmon resonance energy transfer between urchin-like gold nanoparti-cles and oxidized 2,2'-diazo-bis-3-ethylbenzothiazoline-6-sulfonic acid(ABTS~+)was used to enhance photothermal conversion.UGPs have a wide plasmon reso-nance band from the visible to the near-infrared region,which provides conditions for spectral analysis and applications in the near-infrared region.Based on this,we synthe-sized UGPs which had strong near-infrared absorption by adjusting the number and length of UGPs.Then ABTS~+was selected as the energy acceptor since it also had strong absorption in the near-infrared region,and a new type of composite photother-mal material(UGPs&ABTS&HRP)@Lip was constructed by using liposomes(Lip)and horseradish peroxidase(HRP).Under the trigger of reactive oxygen species,the oxidation products ABTS~+could combined with UGPs by electrostatic adsorption.Then the PRET was took place,and the energy of UGPs could be transferred to ABTS~+through PRET.Under the irradiation of 808 nm laser,ABTS~+further converted the ab-sorbed energy into thermal energy.The strong scattering signals of UGPs could be converted into thermal signals through the PRET between UGPs and ABTS~+,which could enhance the photothermal effect of composite photothermal material(UGPs&ABTS&HRP)@Lip and this material also had the performance of scattering imag-ing.In summary,this paper prepared UGPs with multiple branch structures as the re-search object.UGPs with different LSPR characteristics were specifically prepared by controlling the morphology and size of UGPs.Then UGPs were used as donors to es-tablish novel PRET coupling systems.On the one hand,we had been successfully achieved the highly selective detection of disease markers.On the other hand,a com-posite photothermal material was successfully constructed by the PRET between na-noparticles and photothermal reagents.The composite photothermal material integrated the dark-field scattering properties of the nanoparticles with the photothermal proper-ties of the photothermal reagent,and it could convert the optical signal of the plasma nanoparticles into heat signal.This material not only enhanced the photothermal prop-erties,but also retained the scattering imaging performance and expanded the applica-tion of PRET. |
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