P450-based porous silicon biosensor for arachidonic acid detection

Recent advances in the biosensing of neurotransmitters: material and method overviews towards the biomedical analysis of psychiatric disorders

Neurotransmitters are the most important messengers of the nervous system, and any changes in their balances and activities can cause serious neurological, psychiatric and cognitive disorders such as schizophrenia, Alzheimer's disease and Parkinson's disease.

Novel nanoarchitecture of arginine-glycine-aspartate conjugated gold nanoparticles: a sensitive and selective platform for detecting arachidonic acid

A novel electrochemical approach for determination of arachidonic acid (ARA) was developed based on the linear arginine-glycine-aspartic-Au (RGD-Au) nanomaterial modified on glassy carbon electrode (GCE). The prepared material was characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), ultraviolet-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrochemical signal was obtained from the reduction of 1,4-naphthoquinone and ARA served as a proton source. Under the optimum experimental conditions, the RGD-Au-based electrode was used to analyze ARA. Meanwhile, the electrochemical characteristics were also studied by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). The sensor showed a wider linear range from 0.5 to 100 μM and the linear fitting equation was I_p (μA) = 0.0721 c + 2.4583 (R² = 0.9987) with a detection limit of 80 nM. The application of the sensor in real samples was tested and compared with that of LC-MS/MS. This sensor would be a promising platform for detection of ARA in blood plasma. Graphical abstract.

Crystallographic insights into a cobalt (III) sepulchrate based alternative cofactor system of P450 BM3 monooxygenase

P450 BM3 is a multi-domain heme-containing soluble bacterial monooxygenase. P450 BM3 and variants are known to oxidize structurally diverse substrates. Crystal structures of individual domains of P450 BM3 are available. However, the spatial organization of the full-length protein is unknown. In this study, crystal structures of the P450 BM3 M7 heme domain variant with and without cobalt (III) sepulchrate are reported. Cobalt (III) sepulchrate acts as an electron shuttle in an alternative cofactor system employing zinc dust as the electron source. The crystal structure shows a binding site for the mediator cobalt (III) sepulchrate at the entrance of the substrate access channel. The mediator occupies an unusual position which is far from the active site and distinct from the binding of the natural redox partner (FAD/NADPH binding domain).

Hydatid detection using the near-infrared transmission angular spectra of porous silicon microcavity biosensors

Hydatid, which is a parasitic disease, occurs today in many regions worldwide. Because it can present a serious threat to people's health, finding a fast, convenient, and economical means of detection is important. This paper proposes a label- and spectrophotometer-free apparatus that uses optical biological detection based on porous silicon microcavities. In this approach, the refractive index change induced by the biological reactions of a sample in a porous silicon microcavity is detected by measuring the change in the incidence angle corresponding to the maximum transmitted intensity of a near-infrared probe laser. This paper reports that the proposed method can achieve the label-free detection of 43 kDa molecular weight hydatid disease antigens with high sensitivity.

Spectrometer-free biological detection method using porous silicon microcavity devices

This paper proposes a label-free and spectrometer-free method for biological detection with high detecting resolution. Taking advantage of the optical properties of porous silicon microcavity, the refractive index changes caused by biological reaction can be detected by measuring the incident angle of the minimum reflected light intensity. Based on the above method, label-free eight-base pair DNA detection can be realized with a corresponding detection limit is as low as 87 nM. This method provides high detecting resolution at a low equipment cost, and can be further used to develop an advanced instrument for biological detection.

Laser-written nanoporous silicon diffraction gratings for biosensors

Surface-relief diffraction gratings and planar diffraction gratings directly written on nanoporous silicon layers using 514 nm continuous-wave lasers at very low power (less than 20 mW) were demonstrated. Diffraction-based biosensing application to detect arachidonic acid was experimentally demonstrated at incident light wavelength of 632.8 nm. A comparison in sensing applications was made between the two types of gratings to show the distinct advantage of the planar grating with selective functionalization. Laser-written planar gratings enable directly immobilizing biomolecules in the laser oxidized area of nanoporous silicon, resulting in a new patterned functionalization technique for biosensing applications. The functionalization technique can not only simplify the functionalization procedure in biosensing but also it has potential to increase the sensitivity of sensors by accurately defining grating patterns using the laser direct writing technique.