Kashif Riaz

An Aluminum Nano-Spike electroporation chip for low voltage delivery of molecules to cancer cells

Micro electroporation (EP) devices with high efficiency and cell viability are useful for various biomedical applications, such as drug delivery and screening. However, these devices usually have low reliability due to undesirable electrochemical reactions. In this study, an Aluminum Nano-Spike EP (ANS-EP) chip was fabricated using nano-imprint lithography, electrochemical anodization and MEMS technology. The fabricated device was characterized using cervical cancer cell line (HeLa cells). The EP efficiency and cell viability as functions of electric pulse amplitude and duration were measured using digital fluorescent microscopy with Propidium Iodide (PI) dye. Numerical simulations of electric field strength indicated enhanced localized electric field at the tip due to high aspect ratio of nano-spikes. Systematic experiments revealed EP can be achieved with high efficiency and cell viability using ANS-EP chips without bubble generation at the critical applied voltage of 2.5 V, much smaller than the micro and conventional electroporators.

A novel combination of four flavonoids derived from Astragali Radix relieves the symptoms of cyclophosphamide‐induced anemic rats

By using a feedback system control scheme, the best combination of formononetin, ononin, calycosin, and calycosin‐7‐O‐β‐d‐glucoside derived from Astragali Radix was shown to activate a hypoxia response element, a regulator for erythropoietin (EPO) transcription, in kidney fibroblast. In cyclophosphamide‐induced anemic rats, the treatment of combined flavonoids, or EPO, improved the levels of red blood cells, white blood cells, hemoglobin, and hematocrit. In addition, the altered levels of antioxidant capacity, super oxidase dismutase, and malondialdehyde, triggered in anemic rats, were restored to control levels by the treatment of flavonoids. Here, we proposed a possible therapy by using the common flavonoids in treating anemia.

Optimization of multiple-pulse ultra-low voltage Nanospike electroporation chips using feedback system control for efficient delivery of molecules to cancer cells

We present a rapid and efficient method to optimize the electric pulse parameters for multiple-pulse electroporation (EP) of cancer cells on Nano-spike EP chips to achieve high EP efficiencies (ηEP) and cell viabilities (φcell) at ultra-low voltages. In this paper, feedback system control (FSC) scheme was used for the optimization. The FSC scheme consists of an iterative closed-loop of three operations: combinatory inputs of electric pulse parameters, the experimental readouts, and stochastic search algorithm to find combinations for next iteration. We show that only 11 combinations were needed to obtain the optimized electric pulse parameters with high ηEP and φcell (> 90%) at ultra-low voltage (~ 1 V), much better than that of commercial electroporators. In addition, more than 80% of research time was saved.

Design, Modeling and Simulation of CMOS-MEMS Piezoresistive Cantilever Based Carbon Dioxide Gas Sensor for Capnometry

This paper reports design, modeling and simulation of MEMS based sensor working in dynamic mode with fully differential piezoresistive sensing for monitoring the concentration of exhaled carbon dioxide (CO2) gas in human breath called capnometer. CO2 being a very important biomarker, it is desirable to extend the scope of its monitoring beyond clinical use to home and ambulatory services. Currently the scope of capnometers and its adaption is limited by high cost, large size and high power consumption of conventional capnometers . In recent years, MEMS based micro resonant sensors have received considerable attention due to their potential as a platform for the development of many novel physical, chemical, and biological sensors with small size, low cost and low power requirements. The sensor is designed using 0.35 micron CMOS technology. CoventorWare and MATLAB have been used as simulation software. According to the developed model and simulation results the resonator has resonant frequency 57393 Hz and mass sensitivity of 3.2 Hz/ng. The results show that the longitudinal relative change of resistance is 0.24%/µm while the transverse relative change of resistance is -0.03%/µm.

Smartphone-based electroporator system for micro/nano electroporation chips

A smartphone-based portable electroporator system, “Electroporation Lab on Smartphone,” for the micro/nano EP chips is designed and fabricated for the first time. An android application on a smartphone with a Bluetooth module and a library with different electroporation protocols, such as amplitude, duration, duty cycle and number of pulses is developed to control an Arduino MCU electric pulse generator. This system is successfully used to electroporate HeLa cells in micro/nano EP chips.

Low-cost Nano-spike Bio-Impedance Sensor (NBIS) without surface functionalization for detection and phenotyping of cancer cells

We report a low-cost Nano-spike Bio-Impedance Sensor (nBIS) for detection and phenotyping of cancer/non-cancer cells (HeLa, MCF7 and HEK293). 3D self-aligned nano-spikes, fabricated on a thin aluminum substrate by nanoimprint and electrochemical anodization, were used to measure electrical impedance of cancer cells without surface functionalization. The impedance spectra of cancer and non-cancer cells show significant differences. From the modified Randles model, nano-spike electrodes can significantly reduce electrochemical and polarization problems at the electrode and liquid interface. The limit of detection (LOD) of nBIS was 10 cells/mL. The normalized charge transfer resistance (20-30% difference among different cells) Rct was shown to be a promising electric biomarker for cancer cell detection and phenotyping.

MEMS 3-DoF gyroscope design, modeling and simulation through equivalent circuit lumped parameter model

Pre-fabrication, behavioural and performance analysis with computer aided design (CAD) tools is a common and fabrication cost effective practice. In light of this we present a simulation methodology for a dual-mass oscillator based 3 Degree of Freedom (3-DoF) MEMS gyroscope. 3-DoF Gyroscope is modeled through lumped parameter models using equivalent circuit elements. These equivalent circuits consist of elementary components which are counterpart of their respective mechanical components, used to design and fabricate 3-DoF MEMS gyroscope. Complete designing of equivalent circuit model, mathematical modeling and simulation are being presented in this paper. Behaviors of the equivalent lumped models derived for the proposed device design are simulated in MEMSPRO T-SPICE software. Simulations are carried out with the design specifications following design rules of the MetalMUMPS fabrication process. Drive mass resonant frequencies simulated by this technique are 1.59 kHz and 2.05 kHz respectively, which are ...