High-throughput double emulsion-based microfluidic production of hydrogel microspheres with tunable chemical functionalities toward biomolecular conjugation

Liu, Eric Y.,Jung, Sukwon,Weitz, David A.,Yi, Hyunmin,Choi, Chang-Hyung The Royal Society of Chemistry 2018 Lab on a chip Vol.18 No.2

<P>Chemically functional hydrogel microspheres hold significant potential in a range of applications including biosensing, drug delivery, and tissue engineering due to their high degree of flexibility in imparting a range of functions. In this work, we present a simple, efficient, and high-throughput capillary microfluidic approach for controlled fabrication of monodisperse and chemically functional hydrogel microspheres <I>via</I> formation of double emulsion drops with an ultra-thin oil shell as a sacrificial template. This method utilizes spontaneous dewetting of the oil phase upon polymerization and transfer into aqueous solution, resulting in poly(ethylene glycol) (PEG)-based microspheres containing primary amines (chitosan, CS) or carboxylates (acrylic acid, AA) for chemical functionality. Simple fluorescent labelling of the as-prepared microspheres shows the presence of abundant, uniformly distributed and readily tunable functional groups throughout the microspheres. Furthermore, we show the utility of chitosan's primary amine as an efficient conjugation handle at physiological pH due to its low pKa by direct comparison with other primary amines. We also report the utility of these microspheres in biomolecular conjugation using model fluorescent proteins, R-phycoerythrin (R-PE) and green fluorescent protein (GFPuv), <I>via</I> tetrazine-<I>trans</I>-cyclooctene (Tz-TCO) ligation for CS-PEG microspheres and carbodiimide chemistry for AA-PEG microspheres, respectively. The results show rapid coupling of R-PE with the microspheres' functional groups with minimal non-specific adsorption. In-depth protein conjugation kinetics studies with our microspheres highlight the differences in reaction and diffusion of R-PE with CS-PEG and AA-PEG microspheres. Finally, we demonstrate orthogonal one-pot protein conjugation of R-PE and GFPuv with CS-PEG and AA-PEG microspheres <I>via</I> simple size-based encoding. Combined, these results represent a significant advancement in the rapid and reliable fabrication of monodisperse and chemically functional hydrogel microspheres with tunable properties.</P>

When a good company transgresses: A study of the influences of CSR, moral decoupling, and ethnocentrism

장대련,Joonsuk Jang,Eric Y. Lee,Hosun Lee,Boinn Chang 한국마케팅과학회 2017 Journal of Global Fashion Marketing Vol.8 No.1

Transgressions can result in negative consequences, especially when committed by global companies. Some of the biggest multinational companies in the world take extra steps to be socially responsible and to have positive reputations in domestic and foreign markets. Despite the extra steps that may be taken, it is a common occurrence for some of these companies to commit transgressions. The knowledge of the eff ect of corporate social responsibility (CSR) history and the country of origin of transgressing companies is scarce in studies that examine the consumers’ reasoning process to forgive or not to forgive the transgression. While the moral reasoning process to forgive transgressions has been examined in instances with public fi gures, studies are lacking in the instance of companies. This study will bridge these gaps by examining the eff ects of CSR history and consumer ethnocentrism on the evaluation of companies before and after transgressions. This study will also examine the eff ects of company evaluations before and after transgressions in the reasoning process of consumers. The authors conclude the study by discussing implications for marketing managers and the potential for further research.

Ultrashort Echo Time MRI (UTE-MRI) Quantifications of Cortical Bone Varied Significantly at Body Temperature Compared with Room Temperature

Jerban, Saeed,Szeverenyi, Nikolaus,Ma, Yajun,Guo, Tan,Namiranian, Behnam,To, Sarah,Jang, Hyungseok,Chang, Eric Y.,Du, Jiang Korean Society of Magnetic Resonance in Medicine 2019 Investigative Magnetic Resonance Imaging Vol.23 No.3

Purpose: To investigate the temperature-based differences of cortical bone ultrashort echo time MRI (UTE-MRI) biomarkers between body and room temperatures. Investigations of ex vivo UTE-MRI techniques were performed mostly at room temperature however, it is noted that the MRI properties of cortical bone may differ in vivo due to the higher temperature which exists as a condition in the live body. Materials and Methods: Cortical bone specimens from fourteen donors ($63{\pm}21$ years old, 6 females and 8 males) were scanned on a 3T clinical scanner at body and room temperatures to perform T1, $T2^*$, inversion recovery UTE (IR-UTE) $T2^*$ measurements, and two-pool magnetization transfer (MT) modeling. Results: Single-component $T2^*$, $IR-T2^*$, short and long component $T2^*s$ from bi-component analysis, and T1 showed significantly higher values while the noted macromolecular fraction (MMF) from MT modeling showed significantly lower values at body temperature, as compared with room temperature. However, it is noted that the short component fraction (Frac1) showed higher values at body temperature. Conclusion: This study highlights the need for careful consideration of the temperature effects on MRI measurements, before extending a conclusion from ex vivo studies on cortical bone specimens to clinical in vivo studies. It is noted that the increased relaxation times at higher temperature was most likely due to an increased molecular motion. The T1 increase for the studied human bone specimens was noted as being significantly higher than the previously reported values for bovine cortical bone. The prevailing discipline notes that the increased relaxation times of the bound water likely resulted in a lower signal loss during data acquisition, which led to the incidence of a higher Frac1 at body temperature.

Ultrashort Echo Time MRI (UTE-MRI) Quantifications of Cortical Bone Varied Significantly at Body Temperature Compared with Room Temperature

Saeed Jerban,,Nikolaus Szeverenyi,Yajun Ma,Tan Guo,Behnam Namiranian,Sarah To,장형석,Eric Y. Chang,Jiang Du 대한자기공명의과학회 2019 Investigative Magnetic Resonance Imaging Vol.23 No.3

Purpose: To investigate the temperature-based differences of cortical bone ultrashort echo time MRI (UTE-MRI) biomarkers between body and room temperatures. Investigations of ex vivo UTE-MRI techniques were performed mostly at room temperature however, it is noted that the MRI properties of cortical bone may differ in vivo due to the higher temperature which exists as a condition in the live body. Materials and Methods: Cortical bone specimens from fourteen donors (63 ± 21 years old, 6 females and 8 males) were scanned on a 3T clinical scanner at body and room temperatures to perform T1, T2*, inversion recovery UTE (IR-UTE) T2* measurements, and two-pool magnetization transfer (MT) modeling. Results: Single-component T2*, IR-T2*, short and long component T2*s from bicomponent analysis, and T1 showed significantly higher values while the noted macromolecular fraction (MMF) from MT modeling showed significantly lower values at body temperature, as compared with room temperature. However, it is noted that the short component fraction (Frac1) showed higher values at body temperature. Conclusion: This study highlights the need for careful consideration of the temperature effects on MRI measurements, before extending a conclusion from ex vivo studies on cortical bone specimens to clinical in vivo studies. It is noted that the increased relaxation times at higher temperature was most likely due to an increased molecular motion. The T1 increase for the studied human bone specimens was noted as being significantly higher than the previously reported values for bovine cortical bone. The prevailing discipline notes that the increased relaxation times of the bound water likely resulted in a lower signal loss during data acquisition, which led to the incidence of a higher Frac1 at body temperature.

Dopamine Regulation of Amygdala Inhibitory Circuits for Expression of Learned Fear

Kwon, O.B.,Lee, J.,Kim, H.,Lee, S.,Lee, S.,Jeong, M.J.,Kim, S.J.,Jo, H.J.,Ko, B.,Chang, S.,Park, S.,Choi, Y.B.,Bailey, Craig H.,Kandel, Eric R.,Kim, J.H. Cell Press 2015 Neuron Vol.88 No.2

GABAergic signaling in the amygdala controls learned fear, and its dysfunction potentially contributes to posttraumatic stress disorder (PTSD). We find that sub-threshold fear conditioning leads to dopamine receptor D4-dependent long-term depression (LTD) of glutamatergic excitatory synapses by increasing inhibitory inputs onto neurons of the dorsal intercalated cell mass (ITC) in the amygdala. Pharmacological, genetic, and optogenetic manipulations of the amygdala regions centered on the dorsal ITC reveal that this LTD limits less salient experiences from forming persistent memories. In further support of the idea that LTD has preventive and discriminative roles, we find that LTD at the dorsal ITC is impaired in mice exhibiting PTSD-like behaviors. These findings reveal a novel role of inhibitory circuits in the amygdala, which serves to dampen and restrict the level of fear expression. This mechanism is interfered with by stimuli that give rise to PTSD and may also be recruited for fear-related psychiatric diseases.