RESUMEN

The detection of trace biomarkers is an important supplementary approach for early screening and diagnoses of tumors. An optical fiber near-field enhanced plasmonic resonance immunoprobe is developed for the detection of the hepatocellular carcinoma biomarker, i.e., the alpha-fetoprotein. Generic principles based on dispersion models and finite element analysis (FEA) models are developed to realize the optimized configuration of spectral characteristics of the immunoprobe. Dispersion models provide theoretical guidance for the design of the multilayer sensing structure from the perspective of the ray optics theory. FEA models provide theoretical guidance for the selection of coating materials from the perspective of the self-defined dielectric constant ratio, i.e., the ratio of the real part to the imaginary part. The optimized configuration of the antibody coupling further improves the biosensing performance of the immunoprobe. The limit of detection (LOD) can reach down to 0.01 ng mL-1 , which is one order of magnitude lower than those relevant reported works. Such a low LOD can more effectively avoid the accuracy degradation of detection results due to measurement errors. Human serum samples have also been detected, with the good precision achieved. This work shows promising prospects in applications of label-free, low-cost, rapid, and convenient early screening of tumors.

Asunto(s)

Técnicas Biosensibles , Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , alfa-Fetoproteínas/análisis , Fibras Ópticas , Carcinoma Hepatocelular/diagnóstico , Neoplasias Hepáticas/diagnóstico

RESUMEN

Cardiac troponin I (cTnI) plays an important role in emergency diagnosis of cardiovascular diseases, which exists predominately in the form of cardiac troponin I-C (cTnI-C) complex. We proposed a fiber-integrated optofluidic chip immunosensor with time-delay-dispersion based microwave photonic analyzer (MPA) for cTnI-C detection. The whispering gallery mode (WGM) fiber probe was fabricated by embedding a polydopamine functionalized hollow glass microsphere (HGMS) into the etched capillary-fiber structure, and the WGMs could be excited through the efficient coupling between the thin-wall capillary and the HGMS. The reflective WGM optofluidic chip functioned as a wavelength tuner to construct fiber ring laser cavity, whose laser output wavelength was cTnI-C concentration-dependent. The tiny wavelength variation of sensing laser was converted into a radio-frequency (RF) response, which was retrieved by measuring the change of RF-domain free spectrum range (FSR) in time-delay-dispersion based MPA, and the quantitative detection of cTnI-C complex can be achieved with high resolution. Experimental results show that this immunosensor had a limit of detection (LOD) of 0.59 ng/mL, and a detection resolution of 1.2 fg/mL. The relative resolving power was 102-104-fold higher than that of others optical fiber cTnI biosensors. The proposed fiber-integrated optofluidic chip provides an innovative lab-on-chip diagnostic tool for myocardial damage.

Asunto(s)

Técnicas Biosensibles , Biomarcadores , Técnicas Biosensibles/métodos , Inmunoensayo , Microondas , Troponina I

RESUMEN

A long-range surface plasmonic resonance (LR-SPR) biosensor modified with double-antibody sandwich immunoassay and plasmonic coupling is demonstrated for human-immunoglobulin G detection with a low limit of detection (LOD). The double-antibody sandwich immunoassay dramatically changes the average refractive index of the medium layer on the sensor surface. The near-field electron coupling between the localized surface plasmon and the long-range surface plasmon leads to a significant perturbation of the evanescent field. The large penetration depth and the long propagation distance of the long-range surface plasmonic waves facilitate the LR-SPR sensor in the detection of biological macromolecules. The unique light absorption characteristic of the nanocomposite material in the sensor provides the in situ self-compensation for the disturbance. Therefore, besides the inherent advantages of optical fiber sensors, the developed biosensor can realize the detection of biomolecules with high sensitivity, low LOD and high accuracy and reliability. Experimental results demonstrate that the LOD of the biosensor is as low as 0.11 µg/mL in the detection of the phosphate-buffered saline sample, and the spike-and-repetition rate is 105.56% in the detection of the real serum sample, which partly shows the practicability of the biosensor. This indicates that the LR-SPR biosensor provides better response compared with existing similar sensors and can be regarded as a valuable method for biochemical analysis and disease detection.

RESUMEN

A type of hollow gold nanoparticle (HGNP)-modified fiber optic long-range surface plasmon resonance (LRSPR) sensor with sensing self-reference is proposed and demonstrated. HGNPs have a stronger plasmonic field compared to solid GNPs because of the coupling between the inner and outer walls of HGNPs. The intense near-field electronic coupling between long-range surface plasmon polaritons associated with the LRSPR gold layer and localized surface plasmon polaritons of HGNPs leads to localized electromagnetic-field enhancement and LRSPR response signal amplification. Therefore, the HGNP-modified LRSPR sensor possesses a more excellent sensing property compared with the unmodified LRSPR sensor. The long-range resonance dip in the transmission spectrum is shown to shift in response to ambient refractivity change, and the characteristic absorption peak is fixed, allowing to regard it as a reference to improve detection accuracy of the sensors. The mode-field distribution of the sensors is simulated by using the finite element method, and the simulation results show that the electric-field intensity on the HGNP surface is significantly enhanced compared with that of the gold layer surface of the unmodified LRSPR sensor. 1874.79 nm/RIU improvement in sensitivity, 1.42 times improvement in figure of merit (FOM), and approximately 50% reduction in limit of detection (LOD) are achieved for the refractivity measurement of a low-concentration biological solution with the employment of HGNPs in LRSPR sensing experiments. The HGNP-modified LRSPR sensor proposed in this paper has high detection accuracy and FOM and low LOD, and can realize remote real-time online monitoring. Therefore, it has important research value and broad application prospects in the field of biochemical detection.

RESUMEN

Cam mechanism is widely applied in industry because it can help achieve various complex motions of the follower via the cam contour design. However, its performance is significantly affected by the wear condition. This study proposes a load distribution measurement instrument to assist the study on friction and wear regularities of oscillating follower cam mechanisms through obtaining the normal pressure (F) and friction force (Ff) distributions along the cam profile. In the instrument, F and Ff are automatically calculated via a MATLAB program based on the geometry and the measured rotary resistance torque and rotary angle of the cam. The latter two parameters are obtained through a static torque sensor and a rotary encoder built in servo motor in real time, respectively. An experimental test was conducted and the cam morphology after service was observed using scanning electron microscopy. Results show that the wear condition of the cam is significantly related to the corresponding F and Ff. Complex load parameters of oscillating follower cam mechanisms can be provided by this instrument, which is crucial in understanding the friction and wear behaviors of cams and finding the vulnerable position.

RESUMEN

GST Alpha 4 (GSTA4) has an important role in the protection against oxidative stress induced by carcinogens such as tobacco smoke. However, few studies investigated the association between GSTA4 polymorphisms and lung cancer risk. We genotyped three selected GSTA4 SNPs (rs182623 - 1718:T > A, rs3798804 + 5034:G > A and rs316141 + 13984:C > T) in a case-control study of 500 lung cancer patients and 517 cancer-free controls and evaluated the association between these SNPs and risk of lung cancer in this Han Chinese population. We found that there was a significant difference in genotype and allele frequency distributions of GSTA4 -1718 between the cases and the controls (P = 0.006 and P = 0.003, respectively). Compared with the GSTA4 -1718TT genotype, individuals with the TA + AA genotypes had a significantly decreased risk of lung cancer (adjusted OR, 0.63; 95% CI, 0.47-0.84; P = 0.006). Although there were no such statistical differences between the cases and controls at the loci +5034 and +13984, nor for histological types, individuals carrying the genotypes of -1718TA, +5034GG and +13984CT had a significantly decreased lung cancer risk (OR, 0.37; 95% CI, 0.23-0.61; P < 0.0001), especially for those smokers who smoked

Asunto(s)

Carcinoma de Pulmón de Células no Pequeñas/genética , Glutatión Transferasa/genética , Neoplasias Pulmonares/genética , Polimorfismo de Nucleótido Simple/genética , Adenocarcinoma/epidemiología , Adenocarcinoma/genética , Carcinoma de Pulmón de Células no Pequeñas/epidemiología , Carcinoma de Células Escamosas/epidemiología , Carcinoma de Células Escamosas/genética , Estudios de Casos y Controles , China/epidemiología , Frecuencia de los Genes , Genotipo , Humanos , Neoplasias Pulmonares/epidemiología , Factores de Riesgo , Carcinoma Pulmonar de Células Pequeñas/epidemiología , Carcinoma Pulmonar de Células Pequeñas/genética , Fumar/efectos adversos

RESUMEN

The relationship between the tenth exon C825T of G-protein ß3 subunit (GNB3) genetic polymorphism and hypertension in the Uygur population of China was investigated. A nested case-control study (n = 738) was carried out. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to genotype GNB3 C825T polymorphism in 354 hypertensive (HT) and 384 normotensive (NT) Uygur subjects. The distributions of GNB3 C825T genotypes were CC (27.2%), TT (42.9%), and CT (29.9%) in the hypertensive subjects and CC (27.7%), TT (42.4%), CT (29.9%) in the normotensive subjects. There were no significant differences in the genotype distributions between the two groups (χ (2) = 0.0262 P = 0.99). The T allele was 51.4% in hypertensive subjects and 51.2% in normotensive subjects, which, between the two groups, was not a significant difference (χ (2) = 0.0016 P = 0.97). Further analysis shows that there is no association between C825T genotypes and age, body mass index (BMI), Glucose (GLU), Triglyceride (TG), Cholesterol (CHO), systolic blood pressure (SBP) and diastolic blood pressure (DBP). No evidence was found to suggest an association between GNB3 C825T polymorphism and hypertension in the Uygur population of China.