• 한국응용과학기술학회지
• /
• 제38권1호
• /
• pp.126-135
• /
• 2021

온도, pH, 빛 및 힘 등의 외부 자극에 반응하여 그 구조나 물리 화학적 특성이 변화 가능한 자극 감응형 하이드로젤에 대한 연구가 활발하게 진행되고 있다. 본 연구에서는 응력 감응형 분자인 스피로피란을 사용하여 응력 및 pH 감응형 하이드로젤을 제조하였다. 먼저, 폴리에틸렌 다이아크릴레이트(PEGDA)를 스피로피란 분자 양 끝에 접목시켜, 수용액에 쉽게 용해될 뿐만 아니라 하이드로젤 가교제 역할이 가능한 아령모양(PEG-spiropyran-PEG)의 SP-PEGDA 분자를 합성하였다. 이렇게 합성한 SP-PEGDA로 가교된 하이드로젤은 팽윤에 의해 발생하는 내부 응력에 의해 노란색의 스피로피란(SP) 분자를 보라색의 메로사인(MC) 형태로 변환시켰다. 또한 pH에 따라 양성화된 메로사인(MCH) 형태로 변환하여 팽윤과 수축을 시각화 하였다.

• 한국막학회:학술대회논문집
• /
• 한국막학회 2001년도 추계 총회 및 학술발표회(한국막학회)
• /
• pp.42-45
• /
• 2001

• 센서학회지
• /
• 제21권4호
• /
• pp.256-262
• /
• 2012

Hyaluronic acid(HA) hydrogels were synthesized by immersing HA microbeads in phosphate buffered saline solutions having different pH levels to assess the effect of pH on the swelling ratio of HA hydrogels for smart drug delivery systems. No beads were formed when the HA solution(below pH 9) was crosslinked with divinyl sulfone(DVS) because DVS is a basic solution. The variation regarding the size of the microbead was not significant, suggesting that the bead size is not a function of pH(10 ~ 14). However, the pore size of the microbeads decreased with increasing pH from 10 to 14, leading to the surface smoothness and dense network as a result of higher crosslinking. The swelling ratio of hydrogels increased when the pH rose from 2(acidic) to 6(neutral). Afterwards, it decreased with further increasing pH(basic). The lower swelling ratio may be due to the lack of ionization of the carboxyl groups. On the other hand, a higher swelling ratio is likely due to the increased electrostatic repulsions between negatively charged carboxyl groups on different chains. Experimental results suggested that pH-responsive HA hydrogels can be applicable to the controlled drug delivery systems.

• Journal of Pharmaceutical Investigation
• /
• 제40권4호
• /
• pp.245-250
• /
• 2010

Porous poly(lactic-co-glycolic acid) microspheres (PLGA MS) have been utilized as an inhalation delivery system and a matrix scaffold system for tissue engineering. Here, gelatin (type A) is introduced as an extractable pH-responsive porogen, which is capable of controlling the porosity and pore size of PLGA microspheres. Porous PLGA microspheres were prepared by a water-in-oil-in-water ($w_1/o/w_2$) double emulsification/solvent evaporation method. The surface morphology of these microspheres was examined by varying pH (2.0~11.0) of water phases, using scanning electron microscopy (SEM). Also, their porosity and pore size were monitored by altering acidification time (1~5 h) using a phosphoric acid solution. Results showed that the pore-forming capability of gelatin was optimized at pH 5.0, and that the surface pore-formation was not significantly observed at pHs of < 4.0 or > 8.0. This was attributable to the balance between gel-formation by electrostatic repulsion and dissolution of gelatin. The appropriate time-selection between PLGA hardening and gelatin-washing out was considered as a second significant factor to control the porosity. Delaying the acidification time to ~5 h after emulsification was clearly effective to make pores in the microspheres. This finding suggests that the porosity and pore size of porous microspheres using gelatin can be significantly controlled depending on water phase pH and gelatin-removal time. The results obtained in this study would provide valuable pharmaceutical information to prepare porous PLGA MS, which is required to control the porosity.

• Korean Chemical Engineering Research
• /
• 제61권4호
• /
• pp.570-575
• /
• 2023

Targeted anticancer drug delivery systems are needed to enhance therapeutic efficacy by selectively delivering drugs to tumor cells while minimizing off-target effects, improving treatment outcomes and reducing toxicity. In this study, a silica-based nanocarrier capable of targeting drug delivery to cancer cells was developed. First, silica nanoparticles were synthesized by the Stöber method using the surfactant cetyltrimethylammonium bromide (CTAB). Increasing the ratio of EtOH in the solvent produced uniformly spherical silica nanoparticles. Washing the nanoparticles removed unreacted residues, resulting in a non-toxic carrier for drug delivery in cells. Upon surface modification, the pH-responsive polymer, polyethyleneimine (PEI) exhibited slow doxorubicin release at pH 7.4 and accelerated release at pH 5.5. By exploiting this feature, we developed a system capable of targeted drug release in the acidic tumor microenvironment.

• 폴리머
• /
• 제33권5호
• /
• pp.441-445
• /
• 2009

본 연구에서는 알부틴, ascorbic acid, 아데노신 등과 같은 화장품 활성물질들을 주변 pH 변화에 따라서 선택적으로 방출하게 하는 지능형 전달시스템을 개발하기 위하여, pH 감응성 P(MAA-co-PEGMA) 수화젤을 분산 광중합을 이용하여 평균 크기 약 $2{\mu}m$의 구형 입자로 합성하였으며, 수화젤 입자는 수화젤의 $pK_a$인 PH 5를 전후로 하여 급격한 팽윤비의 변화를 보여주었다. P (MAA-co-PEGMA) 수화젤에 대한 활성물질들의 탑재에 영향을 미치는 요인들을 알아내기 위하여, 수화젤의 MAA와 EG의 조성과 탑재 pH에 따른 활성물질들의 탑재효율을 조사하였다. 수화젤을 구성하는 MAA와 EG의 조성 중 MAA의 함량이 감소함에 따라서 활성물질들의 탑재효율이 증가하였으며, 탑재 pH에 따른 실험에서는 수화젤과 활성물질들 사이에 형성되는 정전기적 반발력이 최소가 되는 pH보다는 수화젤의 팽윤비가 높게 되는 pH에서 탑재효율이 더 높게 나타났다.

• 청정기술
• /
• 제20권3호
• /
• pp.226-231
• /
• 2014

본 연구는 미세 몰드 기술을 이용하여 산세기 자극에 따라 모양이 변화하는 야누스 입자를 제조하는 방법에 관한 것이다. 야누스 입자는 산세기(pH) 응답형 단량체인 acrylic acid (AA)를 사용하여 친수성 부분을 제조하고, trimethylolpropane triacylate (TMPTA)를 사용하여 소수성 부분을 제조하였다. 제조된 야누스 입자는 산세기 변화에 따라서 친수성 부분의 팽윤이 유도되며 결과적으로 자극 응답성을 가짐을 증명 하였다. 자극 응답성 정도는 산세기의 범위 또는 AA의 조성을 다양화 함으로써 제어가 가능하다. 더 나아가 야누스 입자의 양쪽 부분이 반대 전하를 띄는 특성을 부여하기 위해 AA와 2-(dimethylamino)ethyl methacrylate (DAEMA)를 사용하여 양극성 야누스 입자를 제조하였다. 양극성 야누스 입자는 동일한 산세기 조건에서 서로 다른 팽윤율을 갖게 되며 비대칭적 형상을 띄게 된다. 결론적으로, 본 연구에서는 야누스 입자의 친수성 부분에 산세기 응답형 단량체를 사용함으로써, 산세기 자극에 의해 가역적으로 모양 변형이 가능한 야누스 입자를 제조하였다. 본 연구를 통해 제조된 자극 응답형 야누스 입자는 향후 바이오 센서나 검출 기구 등에 활용 될 것으로 기대한다.

• Bulletin of the Korean Chemical Society
• /
• 제34권6호
• /
• pp.1800-1808
• /
• 2013

Dual-responsive amphiphilic block copolymers were synthesized by combining enzymatic ring-opening polymerization (eROP) of ${\varepsilon}$-caprolactone (CL) and ATRP of N,N-dimethylamino-2-ethyl methacrylate (DMAEMA). The obtained block copolymers were characterized by gel permeation chromatography (GPC), $^1H$ NMR and FTIR-IR. The critical micelle concentration (CMC) of copolymer was determined by fluorescence spectra, it can be found that with hydrophilic block (PDMAEMA) increasing, CMC value of the polymer sample increased accordingly, and the CMC value was 0.012 mg/mL, 0.025 mg/mL and 0.037 mg/mL for $PCL_{50}$-b-$PDMAEMA_{68}$, $PCL_{50}$-b-$PDMAEMA_{89}$, $PCL_{50}$-b-$PDMAEMA_{112}$, $PCL_{50}$-b-$PDMAEMA_{89}$ was chosen as drug carrier to study in vitro release profile of anti-cancer drug (taxol). The temperature and pH dependence of the values of hydrodynamic diameter (Dh) of micelles, and self-assembly of the resulting block copolymers in water were evaluated by dynamic light scattering (DLS). The result showed that with the temperature increasing and pH decreasing, the Dh decreased. Drug-loaded nanoparticles were fabricated using paclitaxel as model. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) had been explored to study the morphology of the hollow micelles and the nanoparticles, revealing well-dispersed spheres with the average diameters both around 80 nm. In vitro release kinetics of paclitaxel from the nanoparticles was also investigated in different conditions (pH and temperature, etc.), revealing that the drug release was triggered by temperature changes upon the lower critical solution temperature (LCST) at pH 7.4, and at $37^{\circ}C$ by an increase of pH.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.261-261
• /
• 2010

Photonic band gap (PBG) materials have been of great interest due to their potential applications in science and technology. Their applications can be further extended when PBG becomes tunable against various chemical and electrical stimuli. In recent, it was found that tunable photonic band gap materials can be achieved by incorporating stimuli-responsive smart gels into PBG materials. For example, the characteristic volume phase transition of gels in response to the various external stimuli including temperature, pH, ionic strength, solvent compositions and electric field were recently combined with the unique optical properties of photonic crystals to form unprecedented highly responsive optical components. Since these responsive photonic crystals are capable of reversibly converting chemical or electrical energy into characteristic optical signals, they have been considered as a good platform for label-free chemical or biological detection, actuators or optical switches as well as a model system for investigating gel swelling behavior. Herein, we report block copolymer photonic gels self-assembled from polystyrene-b-poly (2-vinyl pyridine) (PS-b-P2VP) block copolymers. In this talk, we are going to demonstrate that selective swelling of lamellar structure can be effectively utilized for fabricating PBG materials with extremely large tunability. Optical properties and their applications will be discussed.

• Macromolecular Research
• /
• 제16권6호
• /
• pp.489-491
• /
• 2008

See Full Text