A 1D binary photonic crystal sensor for detecting fat concentrations in commercial milk

Detection and photothermal inactivation of Gram-positive and Gram-negative bloodstream bacteria using photonic crystal biosensor and plasmonic core-shell

Plasmonics and core-shell nanomaterials hold great potential to develop pharmaceuticals and medical equipment due to their eco-friendly and cost effective fabrication procedures. Despite these advancements, combating drug-resistant bacterial infections remains a global challenge. Therefore, this study aims to introduce a tailored theoretical framework for a one-dimensional (1D) photonic crystal biosensor (PCB) composed of (ZrO2/GaN)N/defect layer/(ZrO2/GaN)N, designed to detect Gram-positive and Gram-negative bloodstream bacteria employing the transfer matrix method (TMM). In addition, using the finite difference methods (FDM), the photothermal inactivation of bloodstream bacteria with plasmonic core-shell structures (FeO@AuBiS2) was explored using key factors such as light absorption, heat generation, and thermal diffusion. By incorporating six dielectric layers and contaminated blood into the proposed PCB, a maximum sensitivity of 562 nm per RIU was recorded, and using rod-shaped plasmonic core-shell structures, 5.8 nm-1 light absorption capacity and 152 K change in temperature were achieved. The maximum detection sensitivity, light absorption, heat conduction and heat convection capacity of the proposed 1D PCB and plasmonic core-shell show an effective approach to combating drug-resistant bacteria.

Optical Detection of Fat Concentration in Milk Using MXene-Based Surface Plasmon Resonance Structure

MXene (Ti3C2Tx) has emerged very recently as an interacting material for surface plasmon resonance (SPR) configuration. It was discovered that Ti3C2Tx can facilitate the adsorption of biomolecules due to its higher binding energies, stronger interaction between matter and light, and larger surface area. In this work, a two-dimensional Ti3C2Tx and silicon layer-based SPR refractometric sensor is proposed for the sensitive and fast detection of milk fat concentration due to the high significance of this issue to people all over the world. The proposed SPR structure employs BK7 (BK7 is a designation for the most common Borosilicate Crown glass used for a variety of applications in the visible range) as a coupling prism and silver as a metal layer. The layer thicknesses and the number of Ti3C2Tx sheets are optimized for the highest performance. The highest reached sensitivity is 350 deg./RIU with 50 nm silver and 4 nm silicon with a monolayer of Ti3C2Tx, which is ultra-high sensitivity compared to the latest work that utilizes SPR configuration. The proposed SPR-based sensor's ultra-high sensitivity makes it more attractive for usage in a variety of biosensing applications.

Biophotonic sensor design using a 1D defective annular photonic crystal for the detection of creatinine concentration in blood serum

A new biophotonic sensor composed of a porous silicon (PSi)-based one-dimensional (1D) defective annular photonic crystal (APC) was designed and theoretically investigated using a modified transfer matrix method (TMM) in terms of cylindrical coordinates. The proposed biosensor was found to be capable of sensing very minute variations in the refractive index of blood serum samples of different creatinine concentrations. It can be considered as a useful tool for diagnosing mild to chronic kidney diseases by measuring the creatinine concentration in the blood serum samples of patients. The biosensor design [(AB)^N/2D(AB)^N/2/Si] is composed of two 1D APCs (AB)^N/2 associated with a defect layer D of a blood serum sample of thickness d_d whose creatinine concentration is to be determined. Both 1D APCs are made up of two alternate PSi layers A and B with porosity ratios of 34% and 87%, respectively. Moreover, our proposed biophotonic sensor demonstrated a high value of sensitivity (S) between 637.73 and 640.29 nm per RIU, a quality factor (Q) between 1.51 × 10⁵ and 0.74 × 10⁵, and a figure of merit (FOM) between 2.6 × 10⁴ and 1.96 × 10⁴ RIU, corresponding to a blood serum sample whose creatinine concentration varied between 80.90 to 85.28 μmol L⁻¹. The limit of detection (LOD) was of the order of 10⁻⁶ RIU. This low value LOD confirmed that our biosensor is capable of noticing any minute change in the wavelength up to an order of 10⁻⁶. Compared with previous works, the proposed biosensor design can be easily realized and offers high performance at normal incidence, which allows overcoming the complications involved while achieving a high value of sensitivity in planar PC-based biosensor designs at oblique incidence. Beside this, there is also a possibility to explore this work further for the development of various APC-based biosensing designs with the aim to study various human body fluids.

A new biophotonic sensor composed of a porous silicon (PSi)-based one-dimensional (1D) defective annular photonic crystal (APC) was designed and theoretically investigated using a modified transfer matrix method (TMM) in terms of cylindrical coordinates.