ABSTRACT
Compartmentalizing magnetically controlled drug molecules is critical in several bioanalytical trials and tests, such as drug screening, digital PCR, magnetic hyperthermia, and controlled magnetic drug targeting (MDT). However, several studies have focused on diluting the nonmagnetic drug using various passive devices based on traditional microfabrication and 3D printing techniques, leading to the requirement of sterilized cleanroom facilities and expensive equipment, respectively. This work develops a strategically designed and straightforward lithography-free process to fabricate a magnetic microfluidic device using a multilayered PMMA substrate for concentration-dependent compartmentalization of a magnetically controlled anticancer drug. The device contains an array of outlet chamber wells connected to five primary separation microfluidic channels for collecting different drug concentrations. The microfluidic design geometry, magnet configuration, and fluid flow rate are optimized using FEM (Finite Element Method) simulations to attain a systematic concentration gradient region within the microfluidic channel. A stair-step-like patterned magnet creates an attenuating magnetic force between 0.01-0.24 pN on magnetic nanoparticles, capable of generating the concentration gradient for the clinically acceptable flow range of Q = 0.6-1.1 µL min-1. The chamber well of the device is designed to adapt different cell cultures and simultaneously expose five different concentrations by introducing a predefined concentration from the inlet. As a result, this innovative design provides a predictable concentration control in each well through a single injection port to minimize drug loading errors. The concentration gradient generation of the drug and exposure to cell culture chambers are controlled using the magnetic and drag forces capable of running a time-varying dose screening experiment. The concentration range of the compartmentalized drug sample in the device is determined as 10-480 µg mL-1 using inductively coupled plasma mass spectrometry (ICPMS) measurement and fluorescence intensity. The cytotoxicity test of MCF7 and NIH3T3 cells using the device was consistent with the results obtained with the manual dilution method, resulting in the reusability of the device.
Subject(s)
Microfluidic Analytical Techniques , Animals , Mice , NIH 3T3 Cells , Microfluidics , Cell Culture Techniques , Lab-On-A-Chip DevicesABSTRACT
The manipulation of domain walls (DWs) in strain-mediated magnetoelectric (ME) heterostructures has attracted much attention recently, with potential applications in precise and location-specific manipulation of magnetic nanoparticles (MNPs). However, the manipulation ability in these structures is restricted to magnetostrictive circular ring structures only, where the required onion state is metastable, less thermally stable, and cannot be obtained easily. This work investigates the highly shape anisotropic FeGaB magnetostrictive elliptical ring structures of different aspect ratios and trackwidths on the PMN-PT piezoelectric substrate to manipulate fluid-borne MNPs using active control of DWs. The proposed model utilizes the attribute that the required onion state in a magnetostrictive elliptical ring is thermally stable and easily obtained compared to magnetostrictive circular ring structures. By varying the trackwidth of elliptical rings, nucleated DWs are rotated at different angles to capture and transport fluid-borne MNPs. Up to a critical trackwidth, DW rotation is predicted by dominant stress anisotropy energy that leads the rotation of DWs and attached MNPs toward the dominant tensile strain direction of PMN-PT with reversibility. Increasing the trackwidth beyond the critical trackwidth caused a complete 90° rotation of DWs and attached MNPs without reversibility and is given by dominant shape anisotropy energy. The fundamental relationship of capture probability with the size and velocity of injected MNPs is also demonstrated. The nucleation and rotation of DWs are predicated using the coupled elastodynamic and electrostatic Finite Difference Method (FDM) micromagnetic model. Dynamics of MNP capture and rotation are envisaged using an analytical model.
ABSTRACT
Glancing Angle Deposition (GLAD) technique has been used to fabricate the Ag nanoparticles (NPs) over TiO2 thin film (TF) on the n-Si substrate. The deposited Ag NPs are in the size of 3-5 nm. Open-air annealing has been done at 500 °C and 600 °C for the n-Si/TiO2 TF/Ag NP samples. High Resolution X-ray Diffraction (HRXRD) peaks were identified to calculate the crystalline size of the NPs and rutile phase of the annealed sample were exhibited. Morphological analysis has been done for the sample using Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS) and Atomic Force Microscopy (AFM). The enhancement of plasmonic absorption and modulation in the bandgap for the annealed Ag NPs surrounded TiO2 TF has been verified by UV-Vis Spectroscopy and the bandgap has been calculated using Tauc plot. An overall 2.5 fold and 3 fold enhancement has been observed in the UV region and visible region for n-Si/TiO2 TF/Ag NP annealed at 500 °C and 600 °C samples as compared to the n-Si/TiO2 TF/Ag NP as-deposited samples. The modulation of bandgap due to the sub-band transition and Localized Surface Plasmon Resonance (LSPR) effect of Ag NPs and relevant sub-band transition due to change in annealing temperature has been reported.
