Для просмотра этого контента требуется подписка на Jove Войдите в систему или начните бесплатную пробную версию.
Method Article
We present a protocol to synthesize Janus microhydrogels composed entirely of the same base material, poly(N-isopropylacrylamide) (PNIPAAm), with a clearly compartmentalized structure base on the phase separation of a supersaturated NIPAAm monomer solution. The synthesized Janus microhydrogels show unique properties such as anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability.
Janus microparticles are compartmentalized particles with differing molecular structures and/or functionality on each of their two sides. Because of this unique property, Janus microparticles have been recognized as a new class of materials, thereby attracting a great deal of attention from various research fields. The versatility of these microparticles has been exemplified through their uses as building blocks for self-assembly, electrically responsive actuators, emulsifiers for painting and cosmetics, and carriers for drug delivery. This study introduces a detailed protocol that explicitly describes a synthetic method for designing novel Janus microhydrogels composed of a single base material, poly(N-isopropylacrylamide) (PNIPAAm). Janus microdroplets are firstly generated via a hydrodynamic focusing microfluidic device (HFMD) based on the separation of a supersaturated aqueous NIPAAm monomer solution and subsequently polymerized through exposure to UV irradiation. The resulting Janus microhydrogels were found to be entirely composed of the same base material, featured an easily identifiable compartmentalized morphology, and exhibited anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability. We believe that the proposed method introduces a novel hydrogel platform with the potential for advanced synthesis of multi-functional Janus microhydrogels.
Hydrogels are a network of hydrophilic polymer chains.1 An increasing amount of research in the field of hydrogels has promoted significant advances and revealed their similarity to biological tissues; the properties of hydrogels allow the uptake of large amounts of water while maintaining their structure. Environmentally responsive hydrogels have also been studied extensively because of their ability to swell or shrink reversibly in response to external stimuli.2 Several triggers, including temperature,3-5 pH,6,7 light,8,9 electric fields,10,11 and specific molecules, such as glucose,12,13 have been suggested to control the geometric shape of hydrogels. Among the many environmentally responsive hydrogels currently available, poly(N-isopropylacrylamide) (PNIPAAm), a well-known thermo-responsive hydrogel, exhibits volume shrinkage above a low critical solution temperature (LCST) of 32 °C.14 A recent study by Sasaki et al.15 reported the intriguing liquid-liquid phase separation of supersaturated NIPAAm, which is the monomer of PNIPAAm. According to this report, supersaturated NIPAAm was dissolved with a 10-fold molar excess of H2O, and soon after, the solution separated into two liquid phases when allows to stand at a temperature above 25 °C; by contrast, dilute NIPAAm was dissolved homogeneously under the same conditions.
Microparticles made of environmentally responsive hydrogels are fascinating candidates for application in drug delivery,16,17 catalysis,18 sensing,19,20 and photonics.21 Traditional synthetic methods including emulsion polymerization, are used to produce hydrogel microparticles with polydispersity.22,23 However, certain applications require microparticles with a narrow size distribution, for example, to stabilize the pharmacokinetics of drug delivery.24 Irregularly shaped or polydisperse embolic microparticles aggregate proximally into clusters, leading to chronic inflammatory responses in embolic particles for cancer therapeutic treatment.25,26
The microfluidic approach is at the forefront of research as a means of fabricating micro-sized particles with narrow size distributions and complex shapes.27-31 The advantages of fabricating microparticles in the microfluidic device are predicated by the small characteristic length of the microfluidic device, which results in a low Reynolds number. In contrast to traditional bulk emulsification where drops are formed in parallel, microdroplets produced in microfluidic devices are generated in series and subsequently polymerized into microparticles upon exposure to UV irradiation. The fundamental principle of droplet formation using a microfluidic device is balance between the interfacial tension and the shear force of the sheath fluid acting on the core fluid.
Despite the obvious advantages of microfluidic fabrication of droplets/particles, Janus droplets/particles consisting of the same base material are rarely reported because the internal morphology of these droplets/particles is generally disturbed by the diffusion and perturbation of the core fluids. To circumvent this intrinsic limitation, two groups recently reported the preparation of the Janus microparticles by employing heat-induced phase separation of colloidal nanoparticles and UV-directed phase separation.32,33
To this end, we report a microfluidic approach to synthesize Janus microhydrogels entirely composed of a single base material and obtain a product with clearly compartmentalized morphology. Our approach is based on the primary concept of liquid-liquid phase separation of supersaturated NIPAAm monomer. The resulting Janus microhydrogels were found to possess unique properties including anisotropic thermo-responsiveness and organophilic/hydrophilic loading capability.
1. Изготовление мастер-формы для гидродинамического Сосредоточение микрожидкостных устройств (ФГДМ) через фотолитографии
2. Изготовление ФГМД через PDMS Литейно
Рисунок 1: Обзор процедуры ФГМД Fabrication (а) Конструктивные параметры фотошаблона для ФГМД.. (Б) Иллюстрация процедуры изготовления для ФГМД.ftp_upload / 52813 / 52813fig1large.jpg "целевых =" _blank "> Пожалуйста, нажмите здесь, чтобы посмотреть увеличенную версию этой фигуры.
3. Получение NIPAAm богатых (N-богатых) и NIPAAm бедных (N-бедных) фаз путем фазового разделения перенасыщенного NIPAAm
Рис . 2: Подготовка материала для Janus Microhydrogel синтеза (а) Получение N-богатых и N-бедных растворов мономеров путем разделения фаз перенасыщенной NIPAAm. (Б) Подробная информация о материалах и экспериментальной установки , используемой в протоколе. Пожалуйста , нажмите здесь , чтобы посмотреть увеличенную версию этой фигуры.
4. Синтез Janus Microhydrogels Использование ФГМД
5. Анализ анизотропного Thermo-отзывчивости Janus Microhydrogels
На рисунке 3а представлена схема экспериментальной установки для синтеза Janus microhydrogels через ФГДМ. N-богатых и N-бедные фазы точно впрыскивается в ФГМД в качестве основных жидкостей 1 и 2, а затем объединяются и разбивается на Janus микрокапель в отверстие с ...
Две несмешивающихся базовые материалы, как правило, используются для синтеза microhydrogels Janus. До недавнего времени Януса microhydrogels , состоящие из того же основного материала были редко сообщается и сообщили Janus microhydrogels не имеют четкой внутренней морфологии из - за возмущения , вызванного смеш...
The authors declare that they have no competing financial interests.
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP (Nos. 2014R1A2A1A01006527 and 2011-0030075).
Name | Company | Catalog Number | Comments |
Silicon wafer | LG Siltron | 4", Test grade | Wafer for master mold fabrication |
Acetone | Samchun Pure Chemical | A0097 | Cleaning silicon wafer |
Isopropyl alcohol (IPA) | Daejung Chemicals & Metals | 5035-4404 | Cleaning silicon wafer |
Water purification system | Merck Millipore | EMD Millipore RIOs Essential 5 | Prepering deionized water |
O2 plasma machine | Femto Science | VITA-A | Cleaning silicon wafer |
SU-8 2150 negative photoresist | MicroChem | Y111077 0500L1GL | Photoresist for master mold fabrication |
Hot plate | Misung Scientific | HP330D, HP150D | Baking SU-8 |
SU-8 developer | Microchem | Y020100 4000L1PE | Developing SU-8 |
Mask aligner system for photolithograpy | Shinu Mst Co. | CA-6M | Photolithography |
Sylgard 184 silicone elastomer kit | Dow Corning | 1064891 | PDMS casting |
Laboratory Corona Treater | Electro-technic Products Inc. | Model BD-20AC | PDMS air plasma treatment |
N-isopropylacrylamide (NIPAAm) | Sigma-Aldrich | 415324-50G | Monomer |
N,N'-methylenebisacrylamide (MBAAm) | Sigma-Aldrich | 146072-100G | Crosslinker of NIPAAm |
4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, Irgacure 2959 | BASF | 55047962 | Photoinitiator of NIPAAm |
ABIL EM 90 | Evonik Industries | 201109 | Sufactant for oil |
Vortex mixer | Scientific Industries Inc. | Vortex-Genie 2 | Mixing |
Tygon tubing | Saint-Gobain | I.D. 1/32", O.D. 3/32", Wall 1/32" | Connecting tube between syringes and HFMD |
UV light source | Hamamatsu | Spot light source LC8 | Polymerization from NIPAAm to PNIPAAm |
Syringes, NORM-JECT (3ml) | Henke-Sass Wolf GmbH | 22767 | Loading of materials |
Syringe pump | KD Scientific | KDS model 200 | Perfusion of materials |
Tegitol Type NP-10 | Sigma-Aldrich | NP10-500ML | Surfactant for water |
Oil red O | Sigma-Aldrich | O0625-25G | Dye for N-rich phase |
Oil Blue N | Sigma-Aldrich | 391557-5G | Dye for N-rich phase |
Yellow food dye | Edentown F&B | NA | Dye for N-poor phase |
Green food dye | Edentown F&B | NA | Dye for N-poor phase |
Power supply | Agilent | E3649A | Power soruce for thermoelectric moduel |
Thermoelectric module | Peltier | FALC1-12710T125 | Temparature control |
Centrifuge machine | Labogene | 1248R | Settling down microhydrogels |
24-well plate | SPL Life Sciences | 32024 | Reservoir for observation |
Optical microscope | Nikon | ECLIPSE 80i | Optical observation |
Image analysis software | IMT i-Solution Inc. | iSolutions DT | Measurement of radius |
Запросить разрешение на использование текста или рисунков этого JoVE статьи
Запросить разрешениеThis article has been published
Video Coming Soon
Авторские права © 2025 MyJoVE Corporation. Все права защищены