Thermo-sensitive injectable glycol chitosan-based hydrogel for treatment of degenerative disc disease

Li, Zhengzheng,Shim, Hyeeun,Cho, Myeong Ok,Cho, Ik Sung,Lee, Jin Hyun,Kang, Sun-Woong,Kwon, Bosun,Huh, Kang Moo Elsevier 2018 Carbohydrate Polymers Vol.184 No.-

<P><B>Abstract</B></P> <P>The use of injectable hydrogel formulations have been suggested as a promising strategy for the treatment of degenerative disc disease to both restore the biomechanical function and reduce low back pain. In this work, a new thermo-sensitive injectable hydrogels with tunable thermo-sensitivity and enhanced stability were developed with <I>N</I>-hexanoylation of glycol chitosan (GC) for treatment of degenerative disc disease, and their physico-chemical and biological properties were evaluated. The sol-gel transition temperature of the hydrogels was controlled in a range of 23–56 °С, depending on the degree of hexanoylation and the polymer concentration. <I>In vitro</I> and <I>in vivo</I> tests showed no cytotoxicity and no adverse effects in a rat model. The hydrogel filling of the defective IVD site in an ex vivo porcine model maintained its stability for longer than 28 days. These results suggest that the hydrogel can be used as an alternative material for treatment of disc herniation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A series of thermo-sensitive <I>N</I>-hexanoyl glycol chitosans are synthesized by <I>N</I>-hexanoylation of glycol chitosan. </LI> <LI> The hydrogel system is optimized for thermo-sensitivity, gel stability, and injectability. </LI> <LI> The hydrogels can be useful as an alternative material for treatment of disc disease. </LI> </UL> </P>

Molecular Weight and End Group Effects on the Thermo-responsive Property of Oligomeric N-Isopropylacrylamide

Zhengzheng Li,김온환,민현수,한창권,허강무 한국고분자학회 2010 Macromolecular Research Vol.18 No.6

Pressure drop in packed beds with horizontally or vertically stratified structure

Li, Liangxing,Xie, Wei,Zhang, Zhengzheng,Zhang, Shuanglei Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.11

The paper concentrates on an experimental study of the pressure drop in double-layered packed beds formed by glass spheres, having the configuration of horizontal and vertical stratification. Both single-phase and two-phase flow tests are performed. The pressure drop during the test is recorded and the measured data are compared with those of homogeneous beds consisting of mono-size particles. The results show that for the horizontally stratified bed with fine particles atop coarse particles, the pressure drop in top layer is found higher than those of homogenous bed consisting of the same smaller size particles, while the measured pressure drop of bottom part is similar with those of similar homogenous bed. But for the homologous bed with upside-down structure, the stratification has little or no effect on the pressure drop of the horizontally stratified bed, and the pressure drop of each layer is almost same as that of homogeneous bed packed with corresponding spheres. Additionally, in vertically stratified bed, the pressure drops on the left and right side is almost equal and between those in homogeneous beds. It is speculated that vertically stratified structure may lead to lateral flow which redistributes the flow rate in different parts of packed bed.

Assessment and comparison of three different air quality indices in China

Youping Li,Ya Tang,Zhongyu Fan,Hong Zhou,Zhengzheng Yang 대한환경공학회 2018 Environmental Engineering Research Vol.23 No.1

Air pollution index (API) is used in Mainland China and includes only SO₂, NO₂ and PM10. In 2016, air quality index (AQI) replaced API. AQI contains three more air pollutants (CO, O₃ and PM2.5). Both the indices emphasize on the effect of a single pollutant, whereas the contributions of all other pollutants are ignored. Therefore, in the present work, a novel air quality index (NAQI), which emphasizes on all air pollutants, has been introduced for the first time. The results showed that there were 19 d (5.2%) in API, 28 d (7.7%) in AQI and 183 d (50.1%) in NAQI when the indices were more than 100. In API, PM10 and SO₂ were regarded as the primary pollutants, whereas all five air pollutants in AQI were regarded as primary. Furthermore, four air pollutants (other than the CO) in NAQI were regarded as primary pollutants. PM10, as being the primary pollutant, contributed greatly in these air quality indices, and accounted for 51.2% (API), 37.0% (AQI) and 52.6% (NAQI). The results also showed that particulate matter pollution was significantly high in Luzhou, where stricter pollution control measures should be implemented.

Preparation and characterization of an in situ crosslinkable glycol chitosan thermogel for biomedical applications

오혜민,강은애,Zhengzheng Li,조익성,김다은,MALLICKSUDIPTA,강선웅,노경호,허강무 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Thermogels have been extensively utilized as one of representative in situ forming hydrogel systems forbiomedical applications. However, most thermogels often suffer from a weak mechanical strength andlow physical stability. To overcome these intrinsic weaknesses of conventional thermogels, wedeveloped a new in situ crosslinkable thermogel system with enhanced and tunable physicochemicalproperties. Thermosensitive N-hexanoyl glycol chitosans (HGCs) were synthesized by N-hexanoylationof glycol chitosan and further modified to yield methacrylated HGCs (M-HGCs) and thiolated HGCs (SHHGCs). A mixture of M-HGCs and SH-HGCs (M/SH-HGCs) retained not only their thermogellingproperties but also their reactive functionalities for chemical crosslinking at physiological temperature. Compared to conventional thermogels, the M/SH-HGC thermogels showed enhanced mechanicalproperties due to physical and chemical crosslinking mechanisms. The physicochemical properties of theM/SH-HGC thermogels were characterized in terms of the sol–gel transition temperature, gelation time,mechanical strength, and biodegradability. They showed negligible toxicity in cells, and the in situcrosslinking step did not affect cell viability. These results suggest that our crosslinkable thermogelsystem is useful not only as a new in situ forming hydrogel but also as a biomaterial for variousbiomedical applications due to its thermogelling characteristics and enhanced and tunablephysicochemical properties.

Facile spheroid forming method using thermo-sensitive hydrogel based on glycol chitosan

조명옥,심혜은,Zhengzheng Li,김기석,허강무,강선웅 한국고분자학회 2015 한국고분자학회 학술대회 연구논문 초록집 Vol.2015 No.4

An Energy-Efficient Multicast Algorithm with Maximum Network Throughput in Multi-hop Wireless Networks

Dingde Jiang,Zhengzheng Xu,Wenpan Li,Chunping Yao,Zhihan Lv,Tao Li 한국통신학회 2016 Journal of communications and networks Vol.18 No.5

Energy consumption has become a main problem of sus-tainable development in communication networks and how to com-municate with high energy efficiency is a significant topic that re-searchers and network operators commonly concern. In this paper,an energy-efficient multicast algorithm in multi-hop wireless net-works is proposed aiming at new generation wireless communica-tions. Traditional multi-hop wireless network design only consid-ers either network efficiency or minimum energy consumption ofnetworks, but rarely the maximum energy efficiency of networks. Different from previous methods, the paper targets maximizingenergy efficiency of networks. In order to get optimal energy ef-ficiency to build network multicast, our proposed method triesto maximize network throughput and minimize networks’ energyconsumption by exploiting network coding and sleeping scheme. Simulation results show that the proposed algorithm has better en-ergy efficiency and performance improvements compared with ex-isting methods.

An Energy-Efficient Multicast Algorithm with Maximum Network Throughput in Multi-hop Wireless Networks

Jiang, Dingde,Xu, Zhengzheng,Li, Wenpan,Yao, Chunping,Lv, Zhihan,Li, Tao The Korea Institute of Information and Commucation 2016 Journal of communications and networks Vol.18 No.5

Energy consumption has become a main problem of sustainable development in communication networks and how to communicate with high energy efficiency is a significant topic that researchers and network operators commonly concern. In this paper, an energy-efficient multicast algorithm in multi-hop wireless networks is proposed aiming at new generation wireless communications. Traditional multi-hop wireless network design only considers either network efficiency or minimum energy consumption of networks, but rarely the maximum energy efficiency of networks. Different from previous methods, the paper targets maximizing energy efficiency of networks. In order to get optimal energy efficiency to build network multicast, our proposed method tries to maximize network throughput and minimize networks' energy consumption by exploiting network coding and sleeping scheme. Simulation results show that the proposed algorithm has better energy efficiency and performance improvements compared with existing methods.

Bioinspired tuning of glycol chitosan for 3D cell culture

Cho, Myeong Ok,Li, Zhengzheng,Shim, Hye-Eun,Cho, Ik-Sung,Nurunnabi, Md,Park, Honghyun,Lee, Kuen Yong,Moon, Sung-Hwan,Kim, Ki-Suk,Kang, Sun-Woong,Huh, Kang Moo Nature Publishing Group 2016 NPG Asia Materials Vol.8 No.-

<P>Three-dimensional (3D) cell culture systems have promising applications compared with conventional two-dimensional cell culture systems. Herein, we report a facile method for the formation of 3D spheroids using novel thermo-reversible polysaccharide-based hydrogels. A series of thermo-reversible hydrogels consisting of N-acyl glycol chitosans (NAGCs) are synthesized through a simple N-acylation reaction, and the degree of acylation is finely tuned to obtain adequate thermo-reversible properties and gel stability. Among the NAGCs, N-hexanoyl glycol chitosan is the most thermo-sensitive and is highly effective for forming multi-cellular spheroids when used to coat the surfaces of cell culture dishes. Cell spheroids are effectively formed at various cell concentrations, and their spheroid shape and cellular functions are well maintained for longer times. The hydrogel culture system is also useful for co-cultures that mimic a biological microenvironment. Our thermo-reversible hydrogels may offer a convenient method for the development of in vitro 3D cell culture systems to provide enhanced performance in tissue regeneration, organ-on-chips, drug screening research and other biomedical applications.</P>

N-아세틸화 글리콜 키토산의 합성과 온도감응성 졸-젤 전이 특성

유호선(Ho Seon You),조명옥(Myeong Ok Cho),조익성(Ik Sung Cho),이정정(Zhengzheng Li),김남홍(Nam-Hong Kim),장미경(Mi-Kyeong Jang),강선웅(Sun-Woong Kang),허강무(Kang Moo Huh) 한국고분자학회 2016 폴리머 Vol.40 No.2

본 연구에서는 수용성 천연고분자인 글리콜 키토산의 N-아세틸화를 통해 새로운 천연고분자 기반의 온도감응성 고분자를 합성하고, 온도감응성을 평가하였다. 글리콜 키토산의 N-아세틸화 반응을 통해 글리콜 키틴 구조의 고분자를 성공적으로 합성하였고, 수용액 상에서 37 °C 주변에서 온도감응성 졸-젤 전이현상이 효과적으로 일어남을 확인하였다. 이러한 졸-젤 전이 특성은 기존의 합성고분자 기반 온도감응성 고분자에 비해 상대적으로 더 낮은 농도(3~16 wt%)에서 보였고, 고분자의 분자량, 아세틸화도, 농도를 변화시킴으로써 효과적으로 조절될 수 있었다. 글리콜 키틴은 우수한 온도감응성 뿐 아니라 낮은 세포독성과 향상된 젤 안정성을 보임으로써, 약물전달, 조직공학, 3차원 세포배양 등 다양한 생체의료용 응용분야에 유용하게 활용될 수 있을 것으로 전망된다. In this study, new polysaccharide-based thermo-sensitive polymers were synthesized and their thermo-sensitive sol-gel transition properties were evaluated. Glycol chitin structures were successfully introduced by N-acetylation reaction of glycol chitosan. The aqueous solutions of glycol chitins demonstrated unique thermo-sensitive sol-gel transition behaviors around 37 °C. Their sol-gel transition properties were observed at a relatively lower concentration range (3~16 wt%) compared to those of typical synthetic polymer based systems and efficiently modulated by varying molecular weight, DA, and concentration. Based on their thermo-sensitivity, low cyto-toxicity, and high gel stability, the glycol chitin polymers could be utilized for various biomedical applications, such as drug delivery, tissue engineering, and 3D cell culture.