1,720,978 research outputs found
Toughness and elasticity from phase separation
No full textA simple one-step method that enables the random copolymerization of two monomers with different solubility in ionic liquids creates phase-separated elastic and stiff domains that result in ultra-tough and stretchable ionogels.11Nsciescopu
Flexible and biodegradable electronic implants for diagnosis and treatment of brain diseases
No full text© 2021 The Author(s)In the diagnosis and treatment of brain diseases, implantable devices have immense potential for intracranial sensing of brain activity and application of controlled therapy for providing feedback to the sensing. Flexible materials are preferred for implantable devices, as they can minimise implanted device–brain tissue mechanical mismatch. Moreover, biodegradable implantable devices can reduce potential immunological side-effects. Biodegradability also helps avoid the burdensome secondary surgery for retrieving the implanted device. In this study, we reviewed recent advancements related to the use of flexible and biodegradable type of implantable devices for the diagnosis and treatment of brain diseases. Representative cases of intracranial sensing and feedback therapy are introduced, and then a brief discussion concludes the review.11Nsciescopu
Bioresorbable Electronic Implants: History, Materials, Fabrication, Devices, and Clinical Applications
Full text link© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Medical implants, either passive implants for structural support or implantable devices with active electronics, have been widely used for the diagnosis and treatment of various diseases and clinical issues. These implants offer various functions, including mechanical support of biological structures in orthopedic and dental applications, continuous electrophysiological monitoring and feedback of electrical stimulation in neuronal and cardiac applications, and controlled drug delivery while maintaining arterial structure in drug-eluting stents. Although these implants exhibit long-term biocompatibility, surgery for their retrieval is often required, which imposes physical, biological, and economical burdens on the patients. Therefore, as an alternative to such secondary surgeries, bioresorbable implants that disappear after a certain period of time inside the body, including bioresorbable active electronics, have been highlighted recently. This review first discusses the historical background of medical implants and briefly define related terminology. Representative examples of non-degradable medical implants for passive structural support and/or for diagnosis and therapy with active electronics are also provided. Then, recent progress in bioresorbable active implants composed of biosignal sensors, actuators for therapeutics, wireless power supply components, and their integrated systems are reviewed. Finally, clinical applications of these bioresorbable electronic implants are exemplified with brief conclusion and future outlook11sci
Local Drug Delivery Strategies for Glioblastoma Treatment
No full textGlioblastoma multiforme (GBM) is a brain tumor notorious for its malignancy. The key reason for the limited efficacy of standard treatment is the high recurrence rate of GBM, even after surgical resection. Hence, intensive postsurgical chemical therapies, such as the systemic delivery of various drugs and/or drug combinations, are typically followed after surgery. However, overcoming the blood-brain barrier by systemic administration to efficiently deliver drugs to the brain tumor remains a daunting goal. Therefore, various local drug delivery methods showing potential for improved therapeutic efficacy have been proposed. In particular, the recent application of electronic devices for the controlled delivery of chemotherapy drugs to GBM tissue has attracted attention. We herein review the recent progress of local drug delivery strategies, including electronics-assisted strategies, at the research and commercial level. We also present a brief discussion of the unsolved challenges and future research direction of localized chemotherapy methods for GBM
생체 내 임상 응용을 위한 차세대 생분해성 플랫폼
No full text학위논문(박사) -- 서울대학교 대학원 : 공과대학 화학생물공학부(에너지환경 화학융합기술전공), 2022. 2. 김대형.의료용 임플란트는 대상 부위에 임플란트가 근접하여 위치할 수 있어 웨어러블 기기와 같은 비침습적 시도에 비해 원하는 기능이 크게 향상되기 때문에 다양한 임상 환경에 주목받아 왔다. 임플란트의 중요성에 비추어, 많은 임플란트가 정형외과, 치과, 심장 응용 등 다양한 분야에서 임상적으로 상용화되었다. 하지만 기존 임플란트는 대부분 생체 비활성 물질로 구성돼 있어 예상치 못한 부작용을 초래할 수 있다. 따라서 임플란트를 사용한 후 수술적으로 제거가 필요하지만 이는 환자에게 큰 부담이 된다. 대안으로서, 어떠한 부작용 없이 인체에서 분해되고 흡수될 수 있는 생분해성 물질이 각광받았다.
생분해성 임플란트는 간단한 형태로 만들어져 임상에 시도되어 왔다. 예를 들어, 단일 물질로 구성된 수동형의 생분해성 가능한 임플란트가 임상적으로 사용되기 시작했다(예: 수술용 봉합 및 바이오글루). 그러나 위의 유형은 물리적 지지 기능 이상의 고급 기능을 수행하는 데 한계가 있다. 이러한 필요에 따라, 첨단 생분해성 플랫폼이 다양한 생체 내 응용을 위해 개발되었다. 위 발전은 두 가지 형태로 분류될 수 있다. 첫째, 질병에 대한 심층적인 이해를 바탕으로 특정 용도에 최적화된 기존의 생분해성 재료의 조합에 의한 생분해성 플랫폼 설계이다. 둘째, 목표 장기에 최적화되어 있는 새로운 재료 특성의 생분해성 물질이 개발되었다. 우리는 첫 번째 종류로 분류된 두 개의 새로운 생분해성 플랫폼과 두 번째 종류로 분류된 하나의 새로운 생분해성 물질 포함하여 생체 내 애플리케이션을 위한 세 가지 차세대 생분해성 플랫폼을 제시한다.
첫째, 생체에서 분해가 가능한 무선 전자 장치와 고분자 약물 저장소로 구성된 두개골 내 임플란트가 교모세포종 다형상(GBM) 치료를 위해 개발되었다. 생분해성 전자 패치의 전자 장치는 외부 자기장에 반응하여 무선 열 작동을 가능하게 하여 깊은 곳까지 약물 전달을 용이하게 한다. 뇌척수액으로 약물이 유출되는 것을 방지하는 포장층은 생분해성 전자 패치의 폭발적인 방출과 빠른 생분해를 방지한다. 또한, 생분해성 전자 패치의 물리적 특성, 즉 유연성과 접착성은 절제 수술 후 구불구불한 뇌 표면에 대한 등각 접촉을 가능하게 한다. 생분해성 전자패치의 특성과, 그에 최적화된 프로토콜의 뇌종양 치료 효과를 극대화한다.
둘째, 뇌종양 치료 효과를 보다 더 획기적으로 개선하기 위해 하이드로겔 나노복합체를 개발하였다. 생분해성 전자 패치는 뇌 표면에 위치하기 때문에 심부의 뇌종양으로 약물 전달이 용이하지 않아 뇌종양으로부터의 완전한 회복을 달성할 없었다. 따라서, 우리는 이 문제를 해결하기 위해 온도 감응성 나노복합체를 도입한다. 하이드로겔 나노복합체의 중합체 골격은 온도 감응성 겔화 작용을 나타내는데, 이것은 약물 저장소가 뇌 심부 깊이 형성될 수 있게 하여 침투성 종양 세포를 치료할 수 있게 해준다. 나노복합체의 약물 마이셀은 정상 상태에서 하이드로겔 고분자 골격에 끼이도록 조절되지만, 열 작동의 도움으로 활발하게 방출될 수 있다. 이 열 작동은 하이드로겔 나노복합체에 포함된 수분 분산 강자성 산화철 나노튜브에 의해 가능하다. 이러한 생분해성 재료의 조합은 뇌종양 치료에 매우 최적화된 새로운 생분해성 플랫폼을 가능하게 했고, 쥐 뇌 모델에서 치료 효과를 입증하였다.
셋째, 주입성, 접착성, 신축성 및 생분해성의 특징을 가진 다기능 하이드로겔을 개발하였다. 이전의 연구에 사용된 물질을 포함한 기존의 생분해성 재료는 뇌 이외의 장기에 적용하기에 부적절한 특성을 가지고 있다. 따라서 하이드로겔 전구체의 상세한 설계를 바탕으로 심장, 폐, 방광 등 역동적으로 변화하는 기관에 최적화된 특성을 가진 다기능 하이드로겔을 개발하였다. 이 하이드로겔은 생체 내 응용에 활용될 수 있을 만큼 뛰어난 다기능성을 발휘한다. 또한 나노물질의 하이드로겔로의 통합으로 원래 성능의 저하 없이 하이드로겔에 추가 기능이 부여되어 하이드로겔의 잠재적 효용성이 확장된다. 결과적으로, 다기능 하이드로겔은 다양한 동적 장기에서 생체 내 응용을 통해 그것의 실용성을 입증한다.The medical implants have been utilized for various clinical circumstances, because the proximity of implants to the target site significantly enhances the desired functionality compared to non-invasive attempts such as wearable devices. In light of the importance of the implantable approaches, many clinical implants have been commercialized in diverse fields including orthopedic, dental, and cardiac applications. However, most of the conventional implants are composed of the bio-inert materials, which can induce unexpected side effects. Hence, the surgical retraction after the desired use of implants is necessary, but the additional surgery imposes big burden on patients. As an alternative, bioresorbable materials that degrades and absorbs in the human body without any body responses have been spotlighted.
The bioresorbable implants have been attempted to be administered from a simple form. For example, passive bioresorbable implants composed of a single substance has begun to be clinically used, such as surgical suture and bio-glue. However, the above type has limitations to perform advanced functions over the physical support. By following this demand, the advanced bioresorbable platforms have been developed for various in vivo applications. This development can be classified into two main streams; First, the design of the bioresorbable platform by the combination of conventional bioresorbable materials, optimized for specific application based on in-depth understanding of the disease. Second, new bioresorbable materials whose material properties are optimized for the target organs have been developed. Here, we present three unconventional bioresorbable platforms for in vivo applications, including two novel platforms that are categorized as the first stream and one new materials that are categorized as the second stream.
Firstly, intracranial implant consisting of bioresorbable wireless electronics and a polymeric drug reservoir has been developed for the treatment of glioblastoma multiforme (GBM). The electronics in the bioresorbable electronic patch (BEP) enables wireless thermal actuation in respond to external magnetic field, facilitating the penetrative drug delivery. The encapsulation layer, which prevents direct contact of the electronics and drug-conjugated polymer from the cerebrospinal fluid (CSF), avoids the burst release and rapid degradation of the BEP. Furthermore, the physical properties of the BEP, i.e., flexibility and adhesiveness, enables conformal contact to the curvilinear brain surface after the resection surgery. Such features of the BEP, associated with the optimized protocols, enhances the therapeutic efficacy.
Secondly, the hydrogel nanocomposite has been approached for the dramatic improvement of the GBM treatment efficacy. The BEP could not achieve a full recovery of GBM due to their drug delivery mechanism from the brain surface. Hence, we introduce a thermogel nanocomposite to solve this challenge. The polymer backbone of the nanocomposite exhibits thermo-responsive gelation behavior, which enables the injectable deep drug reservoir into the brain to counter infiltrative tumor cells. The drug micelle in the nanocomposite is modulated to be entrapped in the hydrogel backbone at usual state, but it can be actively released in the aid of thermal actuation. This thermal actuation is enabled by the water-dispersible ferromagnetic iron oxide nanocubes (wFIONs) included in the hydrogel nanocomposite. The combination of such bioresorbable materials makes the novel bioresorbable platform that is highly optimized for the GBM treatment, which proves its therapeutic efficacy in the mouse brain model.
Thirdly, a multifunctional hydrogel with features of injectability, adhesiveness, stretchability, and bioresorbability was reported. Conventional bioresorbable materials, including the materials used in previous researches, have inappropriate characteristics for application to organs other than brain. Therefore, based on the meticulous design of the hydrogel precursors, we develop a multifunctional hydrogel whose properties are optimized for dynamically expandable organs such as heart, lung, and bladder. The hydrogel exhibits superior performance of the multifunctionality enough to be utilized for in vivo applications. Furthermore, with the incorporation of nanofillers, the additional functionality is given to the hydrogel without any degradation of the original performance, expanding the potential utility of the hydrogel. As a result, the multifunctional hydrogel demonstrates its practicality by in vivo applications in various dynamic organs.Abstract i
Contents v
List of Figures vii
Chapter 1. Introduction 1
1.1 The bioresorbable platform for implantable use 1
1.2 Therapeutic approaches for the treatment of glioblastoma multiforme 4
1.3 The development of the hydrogels for in vivo applications 7
1.4 Conclusion 10
1.5 Reference 11
Chapter 2. Bioresorbable electronic patch for GBM treatment 15
2.1 Introduction 15
2.2 Experimental section 17
2.3 Result and discussion 22
2.4 Conclusion 49
2.5 Reference 50
Chapter 3. Hydrogel nanocomposite for GBM treatment 52
3.1 Introduction 52
3.2 Experimental section 55
3.3 Result and discussion 61
3.4 Conclusion 88
3.5 Reference 90
Chapter 4. Multifunctional hydrogel for in vivo diagnosis and therapy 92
4.1 Introduction 92
4.2 Experimental section 94
4.3 Result and discussion 98
4.4 Conclusion 128
4.5 Reference 129박
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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