Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecu...Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecular adsorption and controllable molecular orientation.However,it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate.Herein,we demonstrate a graphene oxide(GO)energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity.The Fermi level(Ef)of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate.Experimentally,kelvin probe force microscopy(KPFM)is employed to quantitatively analyze the Ef of GO.Theoretically,the density functional theory calculations are also performed to verify the proposed modulation mechanism.Consequently,the SERS response of probe molecules with different band structures(R6G,CV,MB,PNTP)can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate.This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.展开更多
The outbreak of coronavirus disease 2019 has seriously threatened human health.Rapidly and sensitively detecting SARSCoV-2 viruses can help control the spread of viruses.However,it is an arduous challenge to apply sem...The outbreak of coronavirus disease 2019 has seriously threatened human health.Rapidly and sensitively detecting SARSCoV-2 viruses can help control the spread of viruses.However,it is an arduous challenge to apply semiconductor-based substrates for virus SERS detection due to their poor sensitivity.Therefore,it is worthwhile to search novel semiconductor-based substrates with excellent SERS sensitivity.Herein we report,for the first time,Nb2C and Ta2C MXenes exhibit a remarkable SERS enhancement,which is synergistically enabled by the charge transfer resonance enhancement and electromagnetic enhancement.Their SERS sensitivity is optimized to 3.0×10^6 and 1.4×10^6 under the optimal resonance excitation wavelength of 532 nm.Additionally,remarkable SERS sensitivity endows Ta2C MXenes with capability to sensitively detect and accurately identify the SARS-CoV-2 spike protein.Moreover,its detection limit is as low as 5×10^−9 M,which is beneficial to achieve real-time monitoring and early warning of novel coronavirus.This research not only provides helpful theoretical guidance for exploring other novel SERS-active semiconductor-based materials but also provides a potential candidate for the practical applications of SERS technology.展开更多
Developing novel nanoparticle-based bioprobes utilized in clinical settings with imaging resolutions ranging from cell to tissue levels is a major challenge for tumor diagnosis and treatment.Herein,an optimized strate...Developing novel nanoparticle-based bioprobes utilized in clinical settings with imaging resolutions ranging from cell to tissue levels is a major challenge for tumor diagnosis and treatment.Herein,an optimized strategy for designing a Fe_(3)O_(4)-based bioprobe for dual-modal cancer imaging based on surface-enhanced Raman scattering(SERS)and magnetic resonance imaging(MRI)is introduced.Excellent SERS activity of ultrasmall Fe_(3)O_(4)nanoparticles(NPs)was discovered,and a 5×10^(-9)M limit of detection for crystal violet molecules was successfully obtained.The high-efficiency interfacial photon-induced charge transfer in Fe_(3)O_(4)NPs was promoted by multiple electronic energy levels ascribed to the multiple valence states of Fe,which was observed using ultraviolet-visible diffuse reflectance spectroscopy.Density functional theory calculations were utilized to reveal that the narrow band gap and high electron density of states of ultrasmall Fe_(3)O_(4)NPs significantly boosted the vibronic coupling resonances in the SERS system upon illumination.The subtypes of cancer cells were accurately recognized via high-resolution SERS imaging in vitro using the prepared Feg Og-based bioprobe with high sensitivity and good specificity.Notably,Fe_(3)O_(4)-based bioprobes simultaneously exhibited T,-weighted MRI contrast enhancement with an active targeting capability for tumors in vivo.To the best of our knowledge,this is the first report on the use of pure semiconductor-based SERS-MRI dual-modal nanoprobes in tumor imaging in vivo and in vitro,which has been previously realized only using semiconductor-metal complex materials.The non-metallic materials with SERS-MRI dual-modal imaging established in this report are a promising cancer diagnostic platform,which not only showed excellent performance in early tumor diagnosis but also possesses great potential for image-guided tumor treatment.展开更多
The detection of circulating tumor cells(CTCs)is a crucial tool for early cancer diagnosis,prognosis,and postoperative evaluation.However,detection sensitivity remains a major challenge because CTCs are extremely rare...The detection of circulating tumor cells(CTCs)is a crucial tool for early cancer diagnosis,prognosis,and postoperative evaluation.However,detection sensitivity remains a major challenge because CTCs are extremely rare in peripheral blood.To effectively detect CTCs,octahedral Ag_(2)O nanoparticles(NPs)with high dispersibility,good biocompatibility,remarkable surface-enhanced Raman scattering(SERS)enhancement,and obvious enhancement selectivity are designed as an SERS platform.Ag_(2)O NPs with many oxygen vacancy defects are successfully synthesized,which exhibit an ultra-high SERS enhancement factor(1.98×10^(6))for 4-mercaptopyridine molecules.The remarkable SERS activity of octahedral Ag_(2)O NPs is derived from the synergistic effect of the surface defect-promoted photo-induced charge transfer(PICT)process and strong vibration coupling resonance in the Ag_(2)O-molecule SERS complex,greatly amplifying the molecular Raman scattering crosssection.The promoted PICT process is confirmed using ultraviolet-visible(UV-Vis)absorption spectroscopy,demonstrating that obvious PICT resonance occurs in Ag_(2)O SERS system under visible light.An additional growth step of SERS bioprobe is proposed by modifying the Raman signal molecules and functional biological molecules on Ag_(2)O NPs for CTC detection.The Ag_(2)O-based SERS bioprobe exhibits excellent detection specificity for different cancer cells in rabbit blood.Importantly,the high-sensitivity Ag_(2)O-based SERS bioprobe satisfies the requirement for rare CTC detection in the peripheral blood of cancer patients,and the detection limit can reach 1 cell per m L.To our knowledge,this study is the first time that a semiconductor SERS substrate has been successfully utilized in CTC detection.This work provides new insights into CTC detection and the development of novel semiconductor-based SERS platforms for cancer diagnosis.展开更多
Understanding the mechanisms of Cu pollution-induced community tolerance (PICT) in soil requires the characterization of Cu-resistant microorganisms at a community level using modern molecular tools. A primer pair (co...Understanding the mechanisms of Cu pollution-induced community tolerance (PICT) in soil requires the characterization of Cu-resistant microorganisms at a community level using modern molecular tools. A primer pair (copAF2010 (5 -TGCAC CTGAC VGGSC AYAT-3 )/copAR2333 (5 -GVACT TCRCG GAACA TRCC-3 )) tentatively targeting Pseudomonas-like Cu-resistant microorganisms was designed in this study. The specification of the primers was tested through conventional polymerase chain reaction (PCR) and the construction of a Pseudomonas-like copA gene fragment library, and then the primers were used to quantify the Cu-resistant microorganisms using quantitative PCR technique. A significant increase of Cu-resistant microorganisms targeted by the primers was observed in a paddy soil from Jiaxing, China which has been exposed to one-year Cu contamination. The results provided direct evidence for Cu PICT in the soil, and the quantification method developed in this study has the potential to be used as a molecular assay for soil Cu pollution.展开更多
Quantum-chemical calculations with the time-dependent density function theory (TDDFT) have been carried out for 5-phenyl-5H-phenanthridin-6-one (PP). For this molecule, dual fluorescence and in- tramolecular charge tr...Quantum-chemical calculations with the time-dependent density function theory (TDDFT) have been carried out for 5-phenyl-5H-phenanthridin-6-one (PP). For this molecule, dual fluorescence and in- tramolecular charge transfer (ICT) were experimentally observed. The B3LYP functional with 6-311+G (2d, p) basis set has been used for the theoretical calculations. The solvent effects have been described within the polarizable continuum model (PCM). Ground-state geometry optimization reveals that the phenyl/phenanthridinone dihedral angle equals 90.0°, a nearly perpendicular structure. Vertical ab- sorption energy calculations characterize the lower singlet excited states both in gas phase and in solvents. It can be found that the lower excited states have locally excitation (LE) feature. Through constructing the potential energy curves of both isolated and solvated systems describing the LE→ICT reaction and fluorescence emission, we obtain the enthalpy difference ΔH between the LE and ICT states, energy barrier Ea, and energy difference δEFC, indicating the structural changes taking place during the ICT reaction. Potential curve and calculated emission energies for both isolated and sol- vated systems show a dual fluorescence phenomenon, consisting of a LE emission band and a red-shifted ICT band. Our calculations including the solvent effects indicate that the dual fluorescence is brought about by the change in molecular structure connected with the planarization of the twisted N-phenylphenanthridinone during the ICT reaction.展开更多
基金financial supports from the National Natural Science Foundation of China (11974222,12004226,12174229,11904214)Natural Science Foundation of Shandong Province (ZR2022YQ02,ZR2020QA075)+2 种基金Qingchuang Science and Technology Plan of Shandong Province (2021KJ006,2019KJJ014,2019KJJ017)Taishan Scholars Program of Shandong Province (tsqn202306152)China Postdoctoral Science Foundation(2019M662423),Shandong Post-Doctoral Innovation Project (202002021).
文摘Surface-enhanced Raman scattering(SERS)substrates based on chemical mechanism(CM)have received widespread attentions for the stable and repeatable signal output due to their excellent chemical stability,uniform molecular adsorption and controllable molecular orientation.However,it remains huge challenges to achieve the optimal SERS signal for diverse molecules with different band structures on the same substrate.Herein,we demonstrate a graphene oxide(GO)energy band regulation strategy through ferroelectric polarization to facilitate the charge transfer process for improving SERS activity.The Fermi level(Ef)of GO can be flexibly manipulated by adjusting the ferroelectric polarization direction or the temperature of the ferroelectric substrate.Experimentally,kelvin probe force microscopy(KPFM)is employed to quantitatively analyze the Ef of GO.Theoretically,the density functional theory calculations are also performed to verify the proposed modulation mechanism.Consequently,the SERS response of probe molecules with different band structures(R6G,CV,MB,PNTP)can be improved through polarization direction or temperature changes without the necessity to redesign the SERS substrate.This work provides a novel insight into the SERS substrate design based on CM and is expected to be applied to other two-dimensional materials.
基金The authors gratefully acknowledge the finical support of the National Key Research and Development Project(No.2017YFB0310600)this work is also supported by Shanghai International Science and Technology Cooperation Fund(Nos.17520711700 and 18520744200).
文摘The outbreak of coronavirus disease 2019 has seriously threatened human health.Rapidly and sensitively detecting SARSCoV-2 viruses can help control the spread of viruses.However,it is an arduous challenge to apply semiconductor-based substrates for virus SERS detection due to their poor sensitivity.Therefore,it is worthwhile to search novel semiconductor-based substrates with excellent SERS sensitivity.Herein we report,for the first time,Nb2C and Ta2C MXenes exhibit a remarkable SERS enhancement,which is synergistically enabled by the charge transfer resonance enhancement and electromagnetic enhancement.Their SERS sensitivity is optimized to 3.0×10^6 and 1.4×10^6 under the optimal resonance excitation wavelength of 532 nm.Additionally,remarkable SERS sensitivity endows Ta2C MXenes with capability to sensitively detect and accurately identify the SARS-CoV-2 spike protein.Moreover,its detection limit is as low as 5×10^−9 M,which is beneficial to achieve real-time monitoring and early warning of novel coronavirus.This research not only provides helpful theoretical guidance for exploring other novel SERS-active semiconductor-based materials but also provides a potential candidate for the practical applications of SERS technology.
文摘Developing novel nanoparticle-based bioprobes utilized in clinical settings with imaging resolutions ranging from cell to tissue levels is a major challenge for tumor diagnosis and treatment.Herein,an optimized strategy for designing a Fe_(3)O_(4)-based bioprobe for dual-modal cancer imaging based on surface-enhanced Raman scattering(SERS)and magnetic resonance imaging(MRI)is introduced.Excellent SERS activity of ultrasmall Fe_(3)O_(4)nanoparticles(NPs)was discovered,and a 5×10^(-9)M limit of detection for crystal violet molecules was successfully obtained.The high-efficiency interfacial photon-induced charge transfer in Fe_(3)O_(4)NPs was promoted by multiple electronic energy levels ascribed to the multiple valence states of Fe,which was observed using ultraviolet-visible diffuse reflectance spectroscopy.Density functional theory calculations were utilized to reveal that the narrow band gap and high electron density of states of ultrasmall Fe_(3)O_(4)NPs significantly boosted the vibronic coupling resonances in the SERS system upon illumination.The subtypes of cancer cells were accurately recognized via high-resolution SERS imaging in vitro using the prepared Feg Og-based bioprobe with high sensitivity and good specificity.Notably,Fe_(3)O_(4)-based bioprobes simultaneously exhibited T,-weighted MRI contrast enhancement with an active targeting capability for tumors in vivo.To the best of our knowledge,this is the first report on the use of pure semiconductor-based SERS-MRI dual-modal nanoprobes in tumor imaging in vivo and in vitro,which has been previously realized only using semiconductor-metal complex materials.The non-metallic materials with SERS-MRI dual-modal imaging established in this report are a promising cancer diagnostic platform,which not only showed excellent performance in early tumor diagnosis but also possesses great potential for image-guided tumor treatment.
基金supported by the National Natural Science Foundation of China(32025021,52002380,31971292,and 51873225)Zhejiang Province Key Research Project(2019C03058)+4 种基金Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)Zhejiang Province Financial Supporting(LQ20E020003)Natural Science Foundation of Ningbo(2019A610024)Ningbo 3315 Innovative Teams Program(2019A-14-C)STS project from the Chinese Academy of Sciences(KFJ-STS-ZDTP-061)。
文摘The detection of circulating tumor cells(CTCs)is a crucial tool for early cancer diagnosis,prognosis,and postoperative evaluation.However,detection sensitivity remains a major challenge because CTCs are extremely rare in peripheral blood.To effectively detect CTCs,octahedral Ag_(2)O nanoparticles(NPs)with high dispersibility,good biocompatibility,remarkable surface-enhanced Raman scattering(SERS)enhancement,and obvious enhancement selectivity are designed as an SERS platform.Ag_(2)O NPs with many oxygen vacancy defects are successfully synthesized,which exhibit an ultra-high SERS enhancement factor(1.98×10^(6))for 4-mercaptopyridine molecules.The remarkable SERS activity of octahedral Ag_(2)O NPs is derived from the synergistic effect of the surface defect-promoted photo-induced charge transfer(PICT)process and strong vibration coupling resonance in the Ag_(2)O-molecule SERS complex,greatly amplifying the molecular Raman scattering crosssection.The promoted PICT process is confirmed using ultraviolet-visible(UV-Vis)absorption spectroscopy,demonstrating that obvious PICT resonance occurs in Ag_(2)O SERS system under visible light.An additional growth step of SERS bioprobe is proposed by modifying the Raman signal molecules and functional biological molecules on Ag_(2)O NPs for CTC detection.The Ag_(2)O-based SERS bioprobe exhibits excellent detection specificity for different cancer cells in rabbit blood.Importantly,the high-sensitivity Ag_(2)O-based SERS bioprobe satisfies the requirement for rare CTC detection in the peripheral blood of cancer patients,and the detection limit can reach 1 cell per m L.To our knowledge,this study is the first time that a semiconductor SERS substrate has been successfully utilized in CTC detection.This work provides new insights into CTC detection and the development of novel semiconductor-based SERS platforms for cancer diagnosis.
基金Supported by the International Copper Association, Rio Tinto Limited, the Nickel Producers Environmental Research Association, the Key International S&T Cooperation Projects of China (No. 2009DFB90120)the National Natural Science Foundation of China (No. 31070101)
文摘Understanding the mechanisms of Cu pollution-induced community tolerance (PICT) in soil requires the characterization of Cu-resistant microorganisms at a community level using modern molecular tools. A primer pair (copAF2010 (5 -TGCAC CTGAC VGGSC AYAT-3 )/copAR2333 (5 -GVACT TCRCG GAACA TRCC-3 )) tentatively targeting Pseudomonas-like Cu-resistant microorganisms was designed in this study. The specification of the primers was tested through conventional polymerase chain reaction (PCR) and the construction of a Pseudomonas-like copA gene fragment library, and then the primers were used to quantify the Cu-resistant microorganisms using quantitative PCR technique. A significant increase of Cu-resistant microorganisms targeted by the primers was observed in a paddy soil from Jiaxing, China which has been exposed to one-year Cu contamination. The results provided direct evidence for Cu PICT in the soil, and the quantification method developed in this study has the potential to be used as a molecular assay for soil Cu pollution.
基金Supported by the Major Scientific Research Project of Southwest University of Science and Technology (Grant No. 053118)
文摘Quantum-chemical calculations with the time-dependent density function theory (TDDFT) have been carried out for 5-phenyl-5H-phenanthridin-6-one (PP). For this molecule, dual fluorescence and in- tramolecular charge transfer (ICT) were experimentally observed. The B3LYP functional with 6-311+G (2d, p) basis set has been used for the theoretical calculations. The solvent effects have been described within the polarizable continuum model (PCM). Ground-state geometry optimization reveals that the phenyl/phenanthridinone dihedral angle equals 90.0°, a nearly perpendicular structure. Vertical ab- sorption energy calculations characterize the lower singlet excited states both in gas phase and in solvents. It can be found that the lower excited states have locally excitation (LE) feature. Through constructing the potential energy curves of both isolated and solvated systems describing the LE→ICT reaction and fluorescence emission, we obtain the enthalpy difference ΔH between the LE and ICT states, energy barrier Ea, and energy difference δEFC, indicating the structural changes taking place during the ICT reaction. Potential curve and calculated emission energies for both isolated and sol- vated systems show a dual fluorescence phenomenon, consisting of a LE emission band and a red-shifted ICT band. Our calculations including the solvent effects indicate that the dual fluorescence is brought about by the change in molecular structure connected with the planarization of the twisted N-phenylphenanthridinone during the ICT reaction.
