An Aluminum Microfluidic Chip Fabrication Using a Convenient Micromilling Process for Fluorescent Poly(dl-lactide-co-glycolide) Microparticle Generation

This study presents the development of a robust aluminum-based microfluidic chip fabricated by conventional mechanical micromachining (computer numerical control-based micro-milling process). It applied the aluminum-based microfluidic chip to form poly(lactic-co-glycolic acid) (PLGA) microparticles encapsulating CdSe/ZnS quantum dots (QDs). A cross-flow design and flow-focusing system were employed to control the oil-in-water (o/w) emulsification to ensure the generation of uniformly-sized droplets. The size of the droplets could be tuned by adjusting the flow rates of the water and oil phases. The proposed microfluidic platform is easy to fabricate, set up, organize as well as program, and is valuable for further applications under harsh reaction conditions (high temperature and/or strong organic solvent systems). The proposed method has the advantages of actively controlling the droplet diameter, with a narrow size distribution, good sphericity, as well as being a simple process with a high throughput. In addition to the fluorescent PLGA microparticles in this study, this approach can also be applied to many applications in the pharmaceutical and biomedical area

Measurement of micro burr and slot widths through image processing: Comparison of manual and automated measurements in micro‐milling

In this study, the burr and slot widths formed after the micro‐milling process of Inconel 718 alloy were investigated using a rapid and accurate image processing method. The measurements were obtained using a user‐defined subroutine for image processing. To determine the accuracy of the developed imaging process technique, the automated measurement results were compared against results measured using a manual measurement method. For the cutting experiments, Inconel 718 alloy was machined using several cutting tools with different geometry, such as the helix angle, axial rake angle, and number of cutting edges. The images of the burr and slots were captured using a scanning electron microscope (SEM). The captured images were processed with computer vision software, which was written in C++ programming language and open‐sourced computer library (Open CV). According to the results, it was determined that there is a good correlation between automated and manual measurements of slot and burr widths. The accuracy of the proposed method is above 91%, 98%, and 99% for up milling, down milling, and slot measurements, respectively. The conducted study offers a user‐friendly, fast, and accurate solution using computer vision (CV) technology by requiring only one SEM image as input to characterize slot and burr formation

PRODUCTION OF LETROZOLE-LOADED MONODISPERSE POLYMERIC-BASED MICROPARTICLES FOR BREAST CANCER THERAPY

Letrozole (LTZ) is effective for the treatment of hormone-receptor-positive breast cancer in postmenopausal women. However, due to its adverse effects this study was designed to investigate the feasibility of producing monodisperse LTZ microparticles using either Poly-ε-Caprolactone (PCL) or Poly (D,L-Lactide) (PDLLA) as polymeric carriers to improve its release and safety profiles. An amount of 1 g PCL or PDLLA was mixed with 5-30% w/w LTZ in 1-2 % w/v ml dichloromethane. Using Vibrating Orifice Aerosol Generator (VOAG) with a 300-µm orifice at a rate of 0.17-1.7 ml/min, and a frequency of 100-1000 KHz, a constant stream of monodisperse microdroplets was generated. These droplets were collected in a 0.04-1% Polyvinyl Alcohol (PVA) aqueous medium and stirred at 250-500 rpm for 24 hours. Solidified microparticles were collected through filtration and dried under vacuum over 48 hours. Optimized microparticles were characterized for yield, morphology, particle size, entrapment efficiency, thermal and structural properties, in vitro release profile, and in vitro cytotoxicity evaluation using 4′,6-Diamidino-2-phenylindole dihydrochloride (DAPI) staining. Monodisperse microparticles were prepared with a high yield that ranged from 88.2-96.1%. Particles appeared to be spherical with smooth surfaces in both carriers. The particle size varied from 15.6 µm to 91.6 µm and from 22.7 µm to 99.6 µm with a span ranging from 0.22 to 1.24 and from 0.29 to 1.48 in PCL- and PDLLA-based formulations, respectively. Liquid flow rate and PVA concentration were the main contributors to the variation in particle size. Upon optimizing the production parameters, span was reduced to 0.162-0.195. High entrapment efficiency was obtained reaching up to 96.8%. LTZ became completely amorphous at 5-10% w/w drug loading using PDLLA, and at all loadings using PCL. Drug release from PDLLA and PCL followed a biphasic zero-order release over 31 days using 5% and 30% w/w drug loadings. In vitro cytotoxicity results have shown that all LZT-PDLLA/PCL formulations significantly inhibited the growth of MCF-7 cell line at low concentrations reaching 10 nM, suggesting its potential clinical importance in suppressing breast tumor growth and invasiveness. This study indicated the potential of manufacturing new LTZ formulations for monthly administration as intramuscular injections (IM) which offer better release profiles that may result in minimal adverse effects

Fabrication of polymeric microchannels with focused and defocused CO2 lasers

 The control of energy distribution or energy intensity inside a laser spot using a defocusing method enables the formation of high-quality microchannels of multiple cross-sections in polycarbonate. Moreover, a thermal mathematical model of the process was developed to aid understanding of the process and to allow channel topology prediction