A high-throughput microfluidic assay to study neurite response to growth factor gradients

Kothapalli, Chandrasekhar R.,van Veen, Ed,de Valence, Sarra,Chung, Seok,Zervantonakis, Ioannis K.,Gertler, Frank B.,Kamm, Roger D. Royal Society of Chemistry 2011 Lab on a chip Vol.11 No.3

<P>Studying neurite guidance by diffusible or substrate bound gradients is challenging with current techniques. In this study, we present the design, fabrication and utility of a microfluidic device to study neurite guidance under chemogradients. Experimental and computational studies demonstrated the establishment of a steep gradient of guidance cue within 30 min and stable for up to 48 h. The gradient was found to be insensitive to external perturbations such as media change and movement of device. The effects of netrin-1 (0.1–10 µg mL<SUP>−1</SUP>) and brain pulp (0.1 µL mL<SUP>−1</SUP>) were evaluated for their chemoattractive potential on neurite turning, while slit-2 (62.5 or 250 ng mL<SUP>−1</SUP>) was studied for its chemorepellant properties. Hippocampal or dorsal root ganglion (DRG) neurons were seeded into a micro-channel and packed onto the surface of a 3D collagen gel. Neurites grew into the matrix in three dimensions, and a gradient of guidance cue was created orthogonal to the direction of neurite growth to impact guidance. The average turning angle of each neurite was measured and averaged across multiple devices cultured under similar conditions to quantify the effect of guidance cue gradient. Significant positive turning towards gradient was measured in the presence of brain pulp and netrin-1 (1 µg mL<SUP>−1</SUP>), relative to control cultures which received no external guidance cue (<I>p</I> < 0.001). Netrin-1 released from transfected fibroblasts had the most positive turning effect of all the chemoattractive cues tested (<I>p</I> < 0.001). Slit-2 exhibited strong chemorepellant characteristics on both hippocampal and DRG neurite guidance at 250 ng mL<SUP>−1</SUP> concentration. Slit-2 also showed similar behavior on DRG neuron invasion into 3D collagen gel (<I>p</I> < 0.01 relative to control cultures). Taken together, the results suggest the utility of this microfluidic device to generate stable chemogradients for studying neurobiology, cell migration and proliferation, matrix remodeling and co-cultures with other cell lines, with potential applications in cancer biology, tissue engineering and regenerative medicine.</P> <P>Graphic Abstract</P><P>We describe a three-channel microfluidic device to study the role of chemogradients on neurite outgrowth and guidance in 3D scaffolds, using experimental and computational studies. The stable chemogradients in these devices could also be used to screen potential drugs for neuron pathway regeneration under disease/ injury conditions, cell migration and cell–cell interactions. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c0lc00240b'> </P>

Unsaturated Fatty Acids and Related Genes as Potential Biomarkers for Breast Cancer

Woo Jung Park,Kumar SD Kothapalli,Peter Lawrence,J. Thomas Brenna 한국식품영양과학회 2012 한국식품영양과학회 학술대회발표집 Vol.2012 No.10

Specific Heat and Thermal Conductivity of UCu4+xAl8−x Compounds

F. Nasreen,M. S. Torikachvili,K. Kothapalli,Y. Kohama,V. S. Zapf,H. Nakotte 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.10

We report on thermal conductivity and specific heat measurements for eight UCu4+xAl8−x compounds (0 ≤ x ≤ 2.0) as a function of temperature and magnetic field. For this series of compounds,previous magnetic and transport studies indicated a transition from magnetic to a non-magnetic heavy fermion state near xcr ≈ 1.15. This paper presents supplementary specific heat and thermal conductivity studies. The ratio of the specific heat over temperature C/T data on the non magnetic compound with xcr ≈ 1.15 show logarithmic dependence with T, a hallmark of non-Fermi liquid (NFL) behavior due to the proximity of a quantum critical point. Compounds with higher Cu content (x > xcr) exhibit unusual temperature scaling in the specific heat possibly due to an increase in disorder between Cu and Al. Thermal conductivity data show stark contrast in the behaviors between the magnetic (x = 0.5) and non-magnetic compound (x = 1.75). Our results confirm that a simple free-electron picture is inadequate for the description of the low-temperature thermal conductivity properties in non-magnetic UCu4+xAl8−x compounds.

Synthesis and Antimicrobial Activity of N-[2-(aryl/substituted aryl)-4-oxo-1,3-thiazolidin-3-yl]pyridine-4-carboxamide

Thomas, Asha B.,Nanda, Rabindra K.,Kothapalli, Lata P.,Deshpande, Avinash D. Korean Chemical Society 2011 대한화학회지 Vol.55 No.6

A series of isonicotinyl hydrazones and their 4-thiazolidinones have been synthesized by condensation of isonicotinic acid hydrazide with various aromatic aldehydes to yield Schiff's bases, followed by the cyclocondensation of Schiff's bases with 2-mercaptoacetic acid to yield their 4-thiazolidinones. The synthesized compounds have been characterized by their elemental, analytical and spectral studies. All these compounds were evaluated for their invitro antimicrobial activity against a spectrum of non-resistant and resistant microbial organisms. These studies proved that compounds 5e,i against B. subtilis; 5e,f,h against B. anthracis; 5g,i against S. aureus showed good activity at lower concentrations. Compounds 5d-5i displayed significant activity against resistant strain of K. pneumonia with minimum inhibitory potency in the concentration range of 2-16 ug/ml.

Detection of Listeria Monocytogenes Using an Automated Fiber-Optic Biosensor: RAPTOR

Kim, Gi Young,Morgan, Mark T.,Ess, Daniel,Hahm, Byoung Kwon,Kothapalli, Aparna,Valadez, Angela,Bhunia, Arun Trans Tech Publications, Ltd. 2006 Key Engineering Materials Vol.321 No.-

<P>Fiber-optic biosensor uses light transmittable tapered fiber to send excitation laser light and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to biomolecules immobilized on the fiber surface [1]. An automated fiber-optic biosensor based detection method for Listeria monocytogenes was developed in this research. Detections of Listeria monocytogenes in hotdog sample were performed to evaluate the method. By using the detection method with automated fiber-optic biosensor, 5.4×107 cfu/ml of Listeria monocytogenes was able to detect.</P>

An Automated Fiber-optic Biosensor Based Binding Inhibition Assay for the Detection of Listeria Monocytogenes

Giyoung Kim,Mark Morgan,Daniel Ess,Byoung-Kwon Hahm,Aparna Kothapalli,Arun Bhunia 한국식품과학회 2007 Food Science and Biotechnology Vol.16 No.3

Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Fiber-optic biosensors have been used to rapidly detect pathogens because they can be very sensitive and are simple to operate. However, many fiber-optic biosensors rely on manual sensor handling and the sandwich assay, which require more effort and are less sensitive. To increase the simplicity of operation and detection sensitivity, a binding inhibition assay method for detecting Listeria monocytogenes in food samples was developed using an automated, fiber-optic-based immunosensor; RAPTOR (Research International, Monroe, WA, USA). For the assay, fiber-optic biosensorswere developed by the immobilization of Listeria antibodies on polystyrene fiber waveguides through a biotin-avidin reaction. Developed fiber-optic biosensors were incorporated into the RAPTOR to evaluate the detection of L. monocytogenes in frankfurter samples. The binding inhibition method combined with RAPTOR was sensitive enough to detect L. monocytogenes (5.4ⅹ10? CFU/mL) in a frankfurter sample.

Binding Inhibition Assay Using Fiber-Optic Based Biosensor for the Detection of Foodborne Pathogens

Morgan, Mark T.,Kim, Gi Young,Ess, Daniel,Kothapalli, Aparna,Hahm, Byoung Kwon,Bhunia, Arun Trans Tech Publications, Ltd. 2006 Key Engineering Materials Vol.321 No.-

<P>Frequent outbreaks of foodborne illness have been increasing the need for simple, rapid and sensitive methods to detect foodborne pathogens. Conventional methods for pathogen detection and identification are labor-intensive and take days to complete. Some immunological rapid assays are developed, but these assays still require prolonged enrichment steps. Biosensors have shown great potential for the rapid detection of foodborne pathogens. Among the biosensors, fiber-optic methods have much potential because they can be very sensitive and simple to operate. Fiber-optic biosensors typically use a light transmittable, tapered fiber to send excitation laser light to the detection surface and receive emitted fluorescent light. The fluorescent light excited by an evanescent wave generated by the laser is quantitatively related to fluorophor-labeled biomolecules immobilized on the fiber surface. A portable and automated fiber-optic biosensor, RAPTOR (Research International, Monroe, WA), was used to detect Salmonella enteritidis in food samples. A binding inhibition assay based on the biosensor was developed to detect the bacteria in hot dog samples. The biosensor and the binding inhibition assay could detect 104 cfu/ml of bacteria in less than 10 min of assay time.</P>