Editorial for the Special Issue on “Micro- and Nanofluidics for Bionanoparticle Analysis”

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Micro- and Nanofluidics for Bionanoparticle Analysis

Bionanoparticles such as microorganisms and exosomes are recoganized as important targets for clinical applications, food safety, and environmental monitoring. Other nanoscale biological particles, includeing liposomes, micelles, and functionalized polymeric particles are widely used in nanomedicines. The recent deveopment of microfluidic and nanofluidic technologies has enabled the separation and anslysis of these species in a lab-on-a-chip platform, while there are still many challenges to address before these analytical tools can be adopted in practice. For example, the complex matrices within which these species reside in create a high background for their detection. Their small dimension and often low concentration demand creative strategies to amplify the sensing signal and enhance the detection speed. This Special Issue aims to recruit recent discoveries and developments of micro- and nanofluidic strategies for the processing and analysis of biological nanoparticles. The collection of papers will hopefully bring out more innovative ideas and fundamental insights to overcome the hurdles faced in the separation and detection of bionanoparticles

Inverted Scanning Microwave Microscope for In Vitro Imaging and Characterization of Biological Cells

This paper presents for the first time an innovative instrument called an inverted scanning microwave microscope (iSMM), which is capable of noninvasive and label-free imaging and characterization of intracellular structures of a live cell on the nanometer scale. In particular, the iSMM is sensitive to not only surface structures, but also ectromagnetic properties up to one micrometer below the surface. Conveniently, the iSMM can be constructed through straightforward conversion of any scanning probe microscope, such as the atomic force microscope or the scanning tunneling microscope, with a simple metal probe to outperform traditional SMM in terms of ruggedness, and width, sensitivity and dynamic range. By contrast, the application of the traditional SMM to date has been limited to mainly surface physics and semiconductor technology, because the traditional SMM requires a fragile and expensive probe and is incompatible with saline solution or live biological cells.Comment: 5 pages, 4 figures, published in Applied Physics Letter

Microfluidic separation of viruses from blood cells based on intrinsic transport processes

Clinical analysis of acute viral infection in blood requires the separation of viral particles from blood cells, since the cytoplasmic enzyme inhibits the subsequent viral detection. To facilitate this procedure in settings without access to a centrifuge, we present a microfluidic device to continuously purify bionanoparticles from cells based on their different intrinsic movements on the microscale. In this device, a biological sample is layered on top of a physiological buffer, and both fluids are transported horizontally at the same flow rate in a straight channel under laminar flow. While the micron sized particles such as cells sediment to the bottom layer with a predictable terminal velocity, the nanoparticles move vertically by diffusion. As their vertical travel distances have a different dependence on time, the micro- and nanoparticles can preferentially reside in the bottom and top layers respectively after certain residence time, yielding purified viruses. We first performed numerical analysis to predicate the particle separation and then tested the theory using suspensions of synthetic particles and biological samples. The experimental results using dilute synthetic particles closely matched the numerical analysis of a two layer flow system containing different sized particles. Similar purification was achieved using diluted blood spiked with human immunodeficiency virus. However, viral purification in whole blood is compromised due to extensive bioparticle collisions. With the parallelization and automation potential offered by microfluidics, this device has the potential to function as an upstream sample preparation module to continuously provide cell depleted bio-nanoparticles for downstream analysis

A REVERSIBLE THERMOSENSTTIVE ADHESIVE FOR RETINAL IMPLANTS In Vivo Experience with Plasma-deposited Poly(N-Isopropyl Acrylamide)

WOS: 000260474200025PubMed: 19430393Purpose: To study the in vivo effects of a thermosensitive retinal adhesive, plasma-polymerized N-isopropyl acrylamide (ppNIPAM), in rabbit eyes. Methods: Parylene C(poly(monochloro-p-xylylene)) (20 mu m) and poly(dimethyl siloxane) (PDMS) (>= 200 mu m) coated with ppNIPAM were used as implant materials. Following pars plana vitrectomy (PPV), ppNIPAM coated parylene (n = 3) and PDMS (n = 3) implants were inserted over the retina in six rabbits. Baseline and follow-up imaging (color fundus photographs, fluorescein angiography, and optic coherence tomography [OCT]) and electroretinogram recordings were performed. Histologic evaluation was performed following enucleation at 6 weeks. Results: Intraoperative retinal adhesion occurred in all eyes with ppNIPAM coated parylene and PDMS implants. Two eyes developed retinal tears during the implantation procedure and the ppNIPAM coated implants closed the retinal tears successfully preventing retinal detachment. OCT findings confirmed the retinal adhesion in all eyes. Four weeks after implantation one parylene and one PDMS implant detached partly from the retinal surface. Histology showed mild changes at the outer retinal segments. There was no evidence of ocular toxicity and inflammation. None of the eyes that had an implant covering the retinal tear developed a retinal detachment but had some inflammatory changes around the implants. Conclusions: ppNIPAM coated implants may provide retinal adhesion in vivo without measurable ocular toxicity in the short term. Covering a retinal tear, the ppNIPAM coated implants may prevent retinal detachment. RETINA 28:1338-1343, 2008National Science FoundationNational Science Foundation (NSF) [EEC 9529161]Supported by the National Science Foundation to UWEB ERC (EEC 9529161)

Correlation between <i>MF</i> and neuronal cell differentiation.

<p>(A) Samples with <i>MF</i> number smaller than 8.3×10⁴ µm³/cell⋅hour had significantly higher numbers of β-tubulin-III positive cells than that of the control. Samples with <i>MF</i> numbers equal to or larger than 8.3×10⁴ µm³/cell⋅hour had similar β-tubulin-III positive cell population compared to the control. (B) Samples with <i>MF</i>s smaller than 8.3×10⁴ µm³/cell⋅hour generally had significantly higher numbers of neuronal cells while samples with <i>MF</i>s equal to or larger than 8.3×10⁴ µm³/cell⋅hour were mostly comparable to the control. (C) The average neurite length had minimal correlation with the <i>MF</i>. The control (with “c”) was C17.2 NSCs seeded at the same surface density in FluoroDishes but without microchannels and fed every 48 hours as in standard subculture protocols. In all data points, N≥15. * indicates statistical difference compared to the control after 1 week, ** for 2 weeks and *** for 3 weeks (p<0.05). The vertical dash line represents the critical <i>MF</i> of 8.3×10⁴ µm³/cell⋅hour.</p