Libin Yang

Improvement of surface-enhanced Raman scattering performance for broad band gap semiconductor nanomaterial (TiO2): Strategy of metal doping

The strategy of metal doping was performed to improve surface-enhanced Raman scattering (SERS) performance for semiconductor TiO2 and deeply understand the contributing/controlling factors of semiconductor (TiO2)-to-molecule charge transfer (CT) mechanism contributed to SERS. The amount and intrinsic nature of doping ions have a great influence on SERS enhancement. An appropriate doping amount of Fe3+, Co2+, and Ni2+ is 0.5%, 1%, 3% mol., respectively, which can enormously improve SERS properties of TiO2 substrate. The considerable SERS enhancement is attributed to doped metal ions, which can embed abundant doping level in TiO2 band gap contributing to semiconductor (TiO2)-to-molecule CT and SERS effect.

Rapid monitoring of benzylpenicillin sodium using Raman and surface enhanced Raman spectroscopy.

At present, fluorescence spectroscopy, ultraviolet spectroscopy and infrared spectroscopy are usually used to detect drug molecules, however the information about using Raman spectroscopy to detect drug molecules is very few. In this work normal Raman spectroscopy and surface-enhanced Raman spectroscopy were utilized to study benzylpenicillin sodium (NaBP). The results show that NaBP is close to the surface of silver substrate through the carboxyl group, and the detection limit of NaBP is reduced to 1×10(-7) mol/L. Accordingly, the quantitative analysis of NaBP can be carried out in the range of 1×10(-4)-1×10(-7) mol/L concentration. And it is proved that NaBP is not stable in acid and alkali conditions and the decomposition reaction is very complex.

Anatase TiO2 nanoparticles with controllable crystallinity as a substrate for SERS: improved charge-transfer contribution

In this paper, TiO2 nanoparticles (NPs) in the anatase phase were synthesized by a very simple sol-hydrothermal method with the assistance of H2SO4. And importantly, the crystallinity and the surface defects (surface state) of anatase TiO2 NPs can be regulated and controlled by this means for improving their SERS performances. The 4-MBA molecule adsorbed on 0.14 mL-H2SO4–TiO2 NPs exhibits the highest SERS enhancement, as compared with the native enhancement on unmodified TiO2 NPs. The introduction of H2SO4 not only enriches the surface defects of anatase TiO2 and the adsorption site, but also improves the separation efficiency of photo-generated carriers, which all can promote the TiO2-to-molecule charge transfer and are mainly responsible for the improved SERS performances.

Improving surface-enhanced Raman scattering properties of TiO2 nanoparticles by metal Co doping

In this paper, pure and different amount Co ions doped TiO2 nanoparticles were synthesized by a sol-hydrothermal method and were served as SERS-active substrate. The effect of metal Co doping on SERS properties of TiO2 nanoparticles was mostly investigated. The results indicate that abundant metal doping energy levels can be formed in the energy gap of TiO2 by an appropriate amount Co ions doping, which can promote the charge transfer from TiO2 to molecule, and subsequently enhance SERS signal of adsorbed molecule on TiO2 substrate, and improve remarkably SERS properties of TiO2 nanoparticles.

High sensitive detection of penicillin G residues in milk by surface-enhanced Raman scattering

The antibiotic residue in animal source foods (milk, meat, etc.) is threatening peoples health due to its abusing in livestock breeding more and more seriously. In this study, a simple and sensitive SERS method coupled with a two-step pretreatment process of sample was proposed for the residue detection of penicillin G (PENG) in real milk sample. It can be found that the two-step pretreatment process of sample is an essential procedure for the successful detection of PENG residue in milk, which can effectively avoid interference from other components in the sample and achieve the trace-level detection of PENG residue by SERS. Under the optimal test conditions, the limit of detection of PENG residue is 2.54×10-9mol/L (equal to 0.85μg/kg), which is lower than the standard of the European Union (4μg/kg). And, there is a good linear relationship (R2=0.9902) in the concentration range of 1.0×10-8~1.0×10-3mol/L. By this method, the recovery of PENG residue ranges from 76% to 97% with relative standard deviation between 4.8% and 2.1%. The proposed SERS method can be effectively applied for determination of PENG residue in milk.

SERS strategy based on the modified Au nanoparticles for highly sensitive detection of bisphenol A residues in milk

Bisphenol A (BPA) is a highly toxic chemical, and its residue in milk product is threatening peoples health due to its possible leaching from the packagings and cans with BPA coating. In this work, halides modified Au nanoparticles (NPs) as the modification substrates were first designed for rapid and sensitive determination of BPA residue in real milk by SERS method with the assistance of aggregation agents (Zn2+). It can be concluded that Au NPs modification substrate with assistance of the aggregation agent can remarkably improve the detection sensitivity of BPA residue, which can significantly enhance the SERS signal of BPA and achieve the trace-level detection of BPA residue. Under the optimal conditions, the limit of detection of BPA residue can be as low as to 4.3 × 10-9mol/L (equal to 0.98 × 10-3mg/kg), which is much less than the standard of European Union (0.6mg/kg). And, there is a good linear relationship (R2 = 0.990) between the intensity of SERS signal and the logarithm of BPA concentration in the range of 1.0 × 10-8-1.0 × 10-3mol/L. By this method, the recovery of BPA residue ranges from 89.5% to 100.2% with relative standard deviation between 4.6% and 2.7%. The proposed SERS method proves to be reliable, highly sensitive and possesses good reproducibility, which is very promising for sensitive detection of bisphenols residue in foodstuff.

SERS investigation and high sensitive detection of carbenicillin disodium drug on the Ag substrate

The reliable and ultrasensitive detection of antibiotic drug residue is of great interest for environmental protection and human health. Herein, we propose a simple SERS strategy based on Ag nanoparticles (NPs) as substrate with the assistance of aggregation agent (MgSO4) for the SERS investigation and the high sensitive detection of antibiotic drug carbenicillin disodium (CBDM). The density functional theory calculation was performed for the assignment and identification of Raman bands of the CBDM molecule. The results indicate that the CBDM molecule is close to the Ag NP substrate surface through the carboxyl group. The CBDM molecules on Ag NP substrate exhibit the largest SERS enhancement, when the concentration of MgSO4 is 1 × 10-2 mol/L and the pH value of CBDM solution is 6. By this SERS method, the limit of detection of CBDM is 0.63 × 10-8 mol/L, which is lower than the standard of European Union for the maximum residue limit of antibiotic drug (1.2 × 10-8 mol/L). And, a quantitative detection method of CBDM can be established. There is a good linear relationship (R2 = 0.9908) in the concentration range of 1.0 × 10-8-1.0 × 10-3 mol/L. It proves that the proposed SERS method is a simple, rapid (within 6 min), reliable and highly sensitive scheme with a good reproducibility for the detection of CBDM. And, the proposed SERS strategy can also be applied for the high sensitive detection and identification of other antibiotic drug (penicillin).