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Microwell Array-based Digital PCR for Influenza Virus Detection
Christian D. Ahrberg,이종민,정봉근 한국바이오칩학회 2019 BioChip Journal Vol.13 No.3
Digital polymerase chain reaction (dPCR) enables the accurate determination of deoxyribonucleic acid (DNA) copy numbers. In contrast to real-time PCR (qPCR), dPCR can perform quantification without requiring previous standard curve experiments. Furthermore, dPCR is more sensitive for rare targets in genetic samples. Despite the significant advantages of dPCR over qPCR, dPCR is not widely applied yet due to the complicated requirements of instrumentations regarding creating sample subvolumes and the equipment cost associated with this. In this paper, we present a microwell array that can be used for dPCR. The microwell array can be operated with little microfluidic expertise, while it can be manufactured at a unit cost of less than 1$. The amplification results of the microwell array can be analyzed with a custom-written Python script. With this method, we have been able to amplify and quantify complementary deoxyribonucleic acid (cDNA) samples for the H7N9 influenza virus in a concentration range spanning three orders of magnitude (1,000-100,000 copies/μL).
Functional Graphene Oxide-Based Nanosheets for Photothermal Therapy
임재현,김다은,김은중,Christian D. Ahrberg,정봉근 한국고분자학회 2018 Macromolecular Research Vol.25 No.6
Cancer is one of the main causes of morbidity and mortality. Although a number of techniques are available for treatment, these methods still have a number of drawbacks, destroying healthy tissues and cells to cause various side effects. Here we present the synthesis and biological application of a composite nanomaterial, folic acid (FA)-conjugated graphene oxide (GO) nanosheets functionalized with manganese dioxide (MnO2) nanoparticles. While FA-conjugated GO nanosheets can be used for targeted photothermal therapy (PTT) when irradiated with a near infrared (NIR) light, MnO2 nanoparticles degrade hydrogen peroxide (H2O2) in the cancer microenvironment, countering hypoxia. Further the nanoparticles can be used as a contrast agent in MRI imaging. We demonstrated that MnO2-FA-GO nanosheets were uptaken by HeLa cells overexpressing FA receptors to induce NIR irradiationmediated hyperthermia (35% viability). Therefore, this composite MnO2-FA-GO nanosheet could be a powerful carrier for cancer targeting and PTT applications.
Dual-nozzle microfluidic droplet generator
최지욱,이종민,Kim Tae Hyun,하장호,Ahrberg Christian D.,정봉근 나노기술연구협의회 2018 Nano Convergence Vol.5 No.12
The droplet-generating microfluidics has become an important technique for a variety of applications ranging from single cell analysis to nanoparticle synthesis. Although there are a large number of methods for generating and experimenting with droplets on microfluidic devices, the dispensing of droplets from these microfluidic devices is a challenge due to aggregation and merging of droplets at the interface of microfluidic devices. Here, we present a microfluidic dual-nozzle device for the generation and dispensing of uniform-sized droplets. The first nozzle of the microfluidic device is used for the generation of the droplets, while the second nozzle can accelerate the droplets and increase the spacing between them, allowing for facile dispensing of droplets. Computational fluid dynamic simulations were conducted to optimize the design parameters of the microfluidic device.
Continuous separation of fungal spores in a microfluidic flow focusing device
Park, Byeong Seon,Kye, Hyeon Gi,Kim, Tae Hyeon,Lee, Jong Min,Ahrberg, Christian D.,Cho, Eun-Min,Yang, Sung Ik,Chung, Bong Geun The Royal Society of Chemistry 2019 The Analyst Vol.144 No.16
<P>The research of fungi is of great importance in a number of fields, such as environmental and healthcare studies. While there are a large number of optical and molecular methods available for characterization and identification of fungi and their spores, their isolation is still conducted using slow and labor-intensive methods. Here, we develop a microfluidic device for the continuous separation of fungal spores from other eukaryotic cells. The spores were separated through the microfluidic device by expanding pinched flow fractionation (PFF) containing the spores, achieving a spatial separation perpendicular to the flow direction according to the spore size. Further branch flow fractionation (BFF) and co-flow of a Newtonian and viscoelastic fluid were used to enhance the separation performance. Using this microfluidic device, we demonstrated the separation of two different types of fungal spores and further separation of fungal spores from eukaryotic cells with a separation efficiency of above 90%. Compared to the existing conventional methods, our microfluidic flow focusing device requires little manual handling and uses small amounts of samples without any pre-treatment steps of the samples.</P>
Functional Graphene Oxide-Based Nanosheets for Photothermal Therapy
Lim, Jae Hyun,Kim, Da Eun,Kim, Eun-Joong,Ahrberg, Christian D.,Chung, Bong Geun The Polymer Society of Korea 2018 Macromolecular Research Vol.26 No.6
Cancer is one of the main causes of morbidity and mortality. Although a number of techniques are available for treatment, these methods still have a number of drawbacks, destroying healthy tissues and cells to cause various side effects. Here we present the synthesis and biological application of a composite nanomaterial, folic acid (FA)-conjugated graphene oxide (GO) nanosheets functionalized with manganese dioxide (<TEX>$MnO_2$</TEX>) nanoparticles. While FA-conjugated GO nanosheets can be used for targeted photothermal therapy (PTT) when irradiated with a near infrared (NIR) light, <TEX>$MnO_2$</TEX> nanoparticles degrade hydrogen peroxide (<TEX>$H_2O_2$</TEX>) in the cancer microenvironment, countering hypoxia. Further the nanoparticles can be used as a contrast agent in MRI imaging. We demonstrated that <TEX>$MnO_2-FA-GO$</TEX> nanosheets were uptaken by HeLa cells overexpressing FA receptors to induce NIR irradiationmediated hyperthermia (35% viability). Therefore, this composite <TEX>$MnO_2-FA-GO$</TEX> nanosheet could be a powerful carrier for cancer targeting and PTT applications.
Conductive hydrogel/nanowire micropattern-based sensor for neural stem cell differentiation
Lee, Jong Min,Moon, Joo Yoon,Kim, Tae Hyun,Lee, Seung Won,Ahrberg, Christian D.,Chung, Bong Geun Elsevier 2018 Sensors and actuators. B, Chemical Vol.258 No.-
<P><B>Abstract</B></P> <P>One of the main challenges regarding treatment of neurodegenerative diseases in the central nervous system (CNS) lies in the inability of neurons to undergo mitosis. Stem cell therapy could provide a possible solution to treat the neurodegenerative diseases. Here, we developed a conductive polyethylene glycol (PEG) hydrogel/silver nanowire (AgNW) composite micropattern-based sensor to direct differentiation of neuronal stem cells (NSCs) and guidance of neurite outgrowth. The ridge micropatterns made from the composite PEG hydrogel/AgNW materials were fabricated on a flexible polyethylene terephthalate (PET) film. Through the combination of these composite materials and the ridge micropatterns, the outgrowth of neurites could be efficiently guided in a controlled manner. Therefore, this conductive PEG hydrogel/AgNW micropattern-based sensor could potentially allow future use of the flexible device as an implant for NSC therapy applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A Conductive hydrogel/silver nanowire composite micropattern-based sensor was developed for neural stem cell differentiation. </LI> <LI> PEG hydrogel/AgNW materials were fabricated on a flexible polyethylene terephthalate (PET) film. </LI> <LI> The outgrowth of neurites was efficiently guided in a controlled manner. </LI> </UL> </P>