Analysis of centrifugal homogenization and its applications for emulsification & mechanical cell lysis

Maintaining sidedness and fluidity in cell membrane coatings supported on nano-particulate and planar surfaces

Supported cell membrane coatings meet many requirements set to bioactive nanocarriers and materials, provided sidedness and fluidity of the natural membrane are maintained upon coating. However, the properties of a support-surface responsible for maintaining correct sidedness and fluidity are unknown. Here, we briefly review the properties of natural membranes and membrane-isolation methods, with focus on the asymmetric distribution of functional groups in natural membranes (sidedness) and the ability of molecules to float across a membrane to form functional domains (fluidity). This review concludes that hydrophilic sugar-residues of glycoproteins in the outer-leaflet of cell membranes direct the more hydrophobic inner-leaflet towards a support-surface to create a correctly-sided membrane coating, regardless of electrostatic double-layer interactions. On positively-charged support-surfaces however, strong, electrostatic double-layer attraction of negatively-charged membranes can impede homogeneous coating. In correctly-sided membrane coatings, fluidity is maintained regardless of whether the surface carries a positive or negative charge. However, membranes are frozen on positively-charged, highly-curved, small nanoparticles and localized nanoscopic structures on a support-surface. This leaves an unsupported membrane coating in between nanostructures on planar support-surfaces that is in dual-sided contact with its aqueous environment, yielding enhanced fluidity in membrane coatings on nanostructured, planar support-surfaces as compared with smooth ones.

Development of simple and efficient Lab-on-a-Disc platforms for automated chemical cell lysis

Cell lysis is the most important first step for molecular biology and diagnostic testing. Recently, microfluidic systems have attracted considerable attention due to advantages associated with automation, integration and miniaturization, especially in resource-limited settings. In this work, novel centrifugal microfluidic platforms with new configurations for chemical cell lysis are presented. The developed systems employ passive form of pneumatic and inertial forces for effective mixing of lysis reagents and cell samples as well as precise fluidic control. Characterizations of the developed Lab-on-a-Discs (LoaDs) have been conducted with dyed deionized (DI) waters and white blood cells (WBCs) to demonstrate the suitability of the proposed systems in terms of mixing, fluidic control and chemical cell lysis. By making comparison between the results of a well-established manual protocol for chemical cell lysis and the proposed chemical cell lysis discs, it has been proved that the developed systems are capable of realizing automated cell lysis with high throughput in terms of proper values of average DNA yield (ranging from 20.6 to 29.8 ng/µl) and purity (ranging from 1.873 to 1.907) as well as suitability of the released DNA for polymerase chain reaction (PCR). By considering the manual chemical lysis protocol as a reference, the efficiency of the LoaDs has been determined 95.5% and 91% for 10 min and 5 min lysis time, respectively. The developed LoaDs provide simple, efficient, and fully automated chemical cell lysis units, which can be easily integrated into operational on-disc elements to obtain sample-to answer settings systems.

Droplet and Particle Generation on Centrifugal Microfluidic Platforms: A Review

The use of multiphase flows in microfluidics to carry dispersed phase material (droplets, particles, bubbles, or fibers) has many applications. In this review paper, we focus on such flows on centrifugal microfluidic platforms and present different methods of dispersed phase material generation. These methods are classified into three specific categories, i.e., step emulsification, crossflow, and dispenser nozzle. Previous works on these topics are discussed and related parameters and specifications, including the size, material, production rate, and rotational speed are explicitly mentioned. In addition, the associated theories and important dimensionless numbers are presented. Finally, we discuss the commercialization of these devices and show a comparison to unveil the pros and cons of the different methods so that researchers can select the centrifugal droplet/particle generation method which better suits their needs.