Qingling Nie,Peipei Xu,Jiajia Liu,Yanhanzhuo Wang,Qian Huang,Ruiyun You,Yunzhen Liu,Lizhi Li,Yudong Lu
To improve the sensitivity, accuracy and specificity of the assay, a two-dimensional silver substrate with EF=5.85×10 8 was first synthesized as a SERS substrate, on the surface of which DSP molecules were modified to form a DSP-antibody coupling through the activation of two N-hydroxy succinimide (NHS) esters to capture TNF-α. Subsequently, aptamerized silver-coated gold nanospheres (Au@TFMBA@Ag) were synthesized as Surface-Enhanced Raman Scattering (SERS) recognition probes. These probes were employed to create a sandwich structure for the quantitative detection of Tumor Necrosis Factor-alpha (TNF-α), utilizing the SERS signal intensity at 1374 cm −1 . Quantitative detection of TNF-α was successfully accomplished within the concentration range of 10 −4 to 10 −10 mg·mL −1 . Clinical serum samples were collected and subjected to testing. Significance analysis, conducted through the T-test (p < 0.0001), unequivocally showed the method's ability to differentiate between sera from normal individuals and those diagnosed with colon cancer.
Yang Chen,Zong-cai Tu,Hui Wang,Guang-xian Liu,Zi-wei Liao,Lu Zhang
In general, the reducing sugars were extensively utilized as additives to prevent denaturation and inactivation during the freeze-drying process. However, different additives have unequal protective effects on the protein conformation. To evaluate the mechanism of protection the protein structure using different additives in the freeze-drying process, the glycated sites and degree of substitution per peptide (DSP) of each site were investigated by LC-Orbitrap MS. We found that the ovalbumin that was supplemented with ribose and then lyophilized (R-oval) have the highest extent of glycation modification. K227 was the most reactive glycated site in R-Oval, with a DSP of 0.83. The ovalbumin that was supplemented with lactose and then lyophilized (L-Oval) have the lowest degree of glycation, and K227 did not undergo the glycation reaction. It was hypothesized that the order impact of different additives on protection of the protein conformation were lactose > galactose > ribose during the freeze-drying process.
Minling Li,Dechan Lu,Ruiyun You,Huiying Shen,Lanjin Zhu,Qingqiang Lin,Yudong Lu
Tyrosinase (TYR) is a key rate-limiting enzyme of melanin and a biomarker for melanoma diagnosis. Therefore, detection of TYR in biological samples is essential for the clinical diagnosis of melanoma. A novel portable surface-enhanced Raman scattering (SERS) sensor is proposed to detect TYR activity. It is based on dopamine (DA)-functionalized Au nanorod (Au NR) arrays as the capture substrate and 4-mercaptophenylboronic acid (4-MPBA)-modified silver nanoparticles (Ag NPs) as the SERS probe. In this case, the Au NR arrays are modified with 3,3′-dithiodipropionic acid di(N-succinimide ester) (DSP) to capture DA. In the presence of TYR, DA is oxidized to dopaquinone (DQ), which resulted in a decrease in the concentration of SERS probes further adsorbed onto the arrays. The activity of TYR is detected by changes in the intensity of the phenylboronic acid signal. Furthermore, this detection system has a wide linear detection range and high sensitivity that can effortlessly evaluate a linear range of 0.0001–100 U/mL of TYR activity. More significantly, the presented SERS sensor can perform well on both the determination of TYR activity in serum and the assessment of TYR inhibitors, which offers new opportunities for diagnosis of melanoma and other TYR-related diseases under complex biological conditions.
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