Search

The sensitive quantification of Human Epidermal growth factor Receptor 2 (HER2), as a key prognostic tumor marker, plays a critical role in screening, early diagnosis and management of breast cancer. This paper describes a sandwich-type immunoassay with silver signal enhancement strategy for highly sensitive detection of HER2. For this purpose, the target capturing step was designed by functionalization of 3-aminopropyltrimethoxysilane coated magnetite nanoparticles with antibody (antiHER2/APTMS-Fe3O4), as a platform bioconjugate (PB), and immobilized at a bare GCE. Then, in the presence of label-free immunosensor, the PB was covered by magnetic gold nanoparticles self-assembled with thiolated antibodies (antiHER2/Hyd@AuNPs-APTMS-Fe3O4) containing chemically reduced silver ions, as a label bioconjugate (LB). Under optimum conditions, a linear relationship between the differential pulse voltammetric (DPV) stripping signal of silver and the logarithm of HER2 concentrations was obtained in the range of 5.0 × 10-4-50.0ngmL-1 (R2 = 0.9906) with a detection limit of 2.0 × 10-5ngmL-1. The effectiveness of this protocol was evaluated experimentally through employing of designed immunosensor for detection of the serum level of tumor marker. The good consistency of the results with those obtained by the enzyme-linked immunosorbent assay (ELISA) conventional method (p-value of < 0.05) showed that this immunosensor can be applied for the testing of HER2 in clinical samples of breast cancer patients.

Background The methylenetetrahydrofolate reductase (MTHFR) gene is involved in DNA methylation, synthesis and repair, which influences the risk of cancers. Many studies have demonstrated that the MTHFR rs1801133 and rs1801131 polymorphisms are linked with the risks of colorectal cancer (CRC). However, no study has probed the relationship between these polymorphisms and CRC risk in southeast Iranian population. Therefore, the aim of this study was to investigate the association of these two polymorphisms with CRC risk in a case-control investigation. Methods A total of 200 confirmed CRC patients and 200 healthy controls (matched to sex and age) were recruited from the Southeast of Iran between 2014 and 2019. Genomic DNA was extracted and genotyped for the polymorphisms using the polymerase chain reaction-restriction fragment length polymorphism method. The relationship between the polymorphism and CRC risk was evaluated by logistical regression analysis. Results MTHFR 667C>T polymorphism was significantly associated with a lower risk of CRC (TT vs CC: p-value = 0.021; CT vs CC: p-value = 0.047; CT+TT vs CC: p-value = 0.017). The T-allele was associated with decreased risk for CRC (p-value = 0.012). However, we did not observe any association of 1298A>C with CRC. Furthermore, stratified analysis showed that MTHFR 667C>T polymorphism was correlated with tumor location in CRC patients. The frequency of T-A haplotype was significantly higher in the healthy controls compared to CRC patients (p-value = 0.021). Conclusion In conclusion, the T-allele of MTHFR 667C>T polymorphism was related to decreased susceptibility to CRC in this Iranian population. Moreover, the CT-AA and TT-AA combined genotypes and T-A haplotype of MTHFR 667C>T and 1298A>C polymorphisms were associated with decreased risk of CRC.

The application of digital micromirror device (DMD) for maskless lithography and vat photopolymerization in the micro-fabrication processes is increasing. Therefore, a high-fidelity model that describes the DMD’s light propagation in a medium is required. To achieve this goal, we initially measured the light field and the intensity evolution beyond its focal plane for a single pixel and multi-pixels pattern. Then, the divergent angle of the field has been obtained. In order to identify the effect of a light field in a vat polymerization performance, two scenarios were investigated: with and without light field effect (LFE). The measured light field data, as well as a uniform light field (without LFE), are fed to a previously developed FEM Multiphysics simulation software as an input. The simulation consists of photochemical kinetic reactions and light attenuation. For each scenario, the output was captured to generate distribution contours that represent the variations in the degree of conversion in the medium. The influence of LFE was investigated for two separate regions: the center and sidewall of the exposed pattern. The evolution of sidewalls angle vs. curing depth was experimentally validated.

Projection-based stereolithography (PSL) is an efficient way for rapid fabrication of 3D structures. However, it is suitable for small parts requiring high resolution. The scanning-based SL (SSL) covers a larger area with a lower resolution. Fabrication time in PSL is intrinsically less than SSL due to exposing an entire image field in a single shot. This study introduces a new scanning-projection based stereolithography (SPSL) to include the advantages of both former methods. SPSL takes advantage of a digital micromirror device (DMD) and a moving stage to combine the projection and scanning methods. The DMD moves continuously over the medium while the projected pattern is continuously updated to allow the fabrication of large layers. After modeling the approach, an experimental setup is assembled to produce real parts. An economical ultra violet light-emitting diode (UV-LED) is used as a light source for curing. Seven 3D models with defined geometry consisted of circular, rectangular, complex and overhanging parts are selected. Five copies of each model are built. The experimental results show that the method is feasible and versatile. The achieved standard deviation is lower than 32 μm.

There are currently no analytical methods available which determine the exact arc length for NURBS curves and for this reason, a smooth feedrate profile with desired trajectory cannot be achieved. Numerical methods used to calculate the arc length are time-consuming processes which make generating a feedrate profile with desired accelerations difficult in real-time. This paper introduces a look-ahead trajectory generation method which determines the deceleration stage according to the fast estimated arc length and the reverse interpolation of each curve at every sampling time. This results in a feedrate trajectory generation with jerk-limited acceleration profiles for the NURBS curves. The feedrate profile is adjusted dynamically according to the geometrical path constraint determined by chord error for the curved path. A NURBS curve by two different kinematics conditions was used as a means to test the feasibility of the developed interpolation scheme and command generator.

In this work, a novel gadolinium membrane sensor based on new S–N Schiff,s base (2-[{3-[(2-sulfanylphenyl)imino)-1-methylbutylidene}amino]phenyl hydrosulfide (SMPH) is presented. The sensor displays a linear dynamic range between 1.0×10−1 and 1.0×10−5 M, with a nice Nernstian slope of 19.8±0.3 mV per decade and a detection limit of 3.0×10−6 M. The best performance was obtained with a membrane composition of 33% poly(vinyl chloride), 61% benzyl acetate, 2% sodium tetraphenyl borate and 5% SMPH. The potentiometric response of the sensor is independent of the pH of the solution in the pH range of 4.0–8.0. The sensor possesses the advantages of short conditioning time, very fast response time, and especially, very good selectivity towards a large number of cations, such as Sm(III), Ce(III), La(III), Cu(II), Pb(II) and Hg(II). The electrode can be used for at least 9 weeks without any considerable divergence in the potentials. It was used as an indicator electrode in potentiometric titration of Gd(III) ions with EDTA, and recovery of Gd(III) from various binary mixtures. The electrode was also applied to the determination of Gd(III) in a urine sample.