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Intracorneal injection of a detachable hybrid microneedle for sustained drug delivery
Lee, KangJu,Song, Hyun Beom,Cho, Wonwoo,Kim, Jin Hyoung,Kim, Jeong Hun,Ryu, WonHyoung Elsevier 2018 Acta Biomaterialia: structure-property-function re Vol.80 No.-
<P><B>Abstract</B></P> <P>There are increasing demands for long-term and controlled corneal drug delivery to treat various ocular diseases. Although biodegradable ocular inserts or contact lenses have been developed, the invasiveness and inefficiency of the approaches still need to be improved. Microneedle (MN) technology can deliver therapeutic molecules to the eye in a minimally invasive manner. However, the current ocular MN technology is limited to either short-term corneal drug delivery or retinal drug delivery by suprachoroidal injection. For long-term and minimally invasive corneal drug delivery, we have developed a detachable biodegradable MN that can be delivered to the inside of the cornea for sustained drug release. The detachable and biodegradable MN is a hybrid MN consisting of a drug-loaded biodegradable tip and a supporting base. The hybrid MN can be applied to the cornea by impact insertion, and it leaves only the drug-loaded biodegradable tip within the corneal tissue so that it can release the drug for a certain period. By concentration-controlled molding, the dimension of drug-loaded MN tips was precisely controlled and their detachability was optimized. The detachable tip and a supporting base were assembled to form a hybrid MN by pressure-assisted transfer molding. We carefully optimized the dimension of the drug-tip, injection dwell time, and insertion depth to achieve effective intracorneal injection of the drug-tip. The detachable hybrid MN was applied to an <I>Acanthamoeba</I> keratitis model wherein a biodegradable drug-tip was successfully delivered to the inside of the mouse cornea <I>in vivo.</I> Follow-up of the MN-treated cases for 7 days confirmed the therapeutic efficacy of the detachable biodegradable MN tips.</P> <P><B>Statement of Significance</B></P> <P>For the treatment of infectious diseases in the cornea, such as keratitis, eye drops need to be applied topically every hour for a couple of days. This is extremely uncomfortable, and poor compliance to such tightly scheduled drug administration can result in permanent scar formation in the cornea. In this work, we demonstrate a simple and rapid injection of biodegradable microneedle tips in the corneal tissue wherein the tips can deliver antibacterial drugs for 4 days to treat keratitis. Unlike other patch-style microneedle technologies, this approach allows for insertion depth-controlled and highly localized injection of detachable individual microneedle tips to the diseased tissue for sustained drug delivery. This overcomes the limitations of patch-style microneedles such as short-term drug delivery and unnecessary blockage of tissue.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
터빈방식 펌프 LPi연료공급 시스템의 엔진 고온재시동 시 LPG 조성비에 따른 연료레일에서의 압력 및 온도특성에 관한 연구
이강주(Kangju Lee),김주원(Juwon Kim),명차리(Cha-Lee Myung),박심수(Simsoo Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
Conventional LPG pump for Liquified Petroleum injection(LPi) engine has been adopted vane type. But the BLDC type fuel pump for LPi system has complicated structure and its price is high. Therefore, as a alternative, this study has mainly focused on the development of turbine type LPG pump which has lower cost and simple structure than conventional BLDC type. To verify the possibility of substitute the performance tests were performed for each fuel pump. The comparative items were pressure settling time, variation of fuel outlet temperature and engine performance of hot restart ability. As a result, performances of turbine type LPG pump were equivalent or high comparing to the BLDC type all over the tests for different fuel composition.
LPG용 터빈방식 연료펌프내부의 압력측정을 통한 토출유량특성에 관한 연구
김주원(Ju-Won Kim),이강주(Kangju Lee),명차리(Cha-Lee Myung),박심수(Simsoo Park),이찬(Chan Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
LPG is usually stored at a temperature close to vaporization. So the available suction pressure to the first stage impeller is essentially only the head of the liquid in the storage tank. To inject the LPG with liquid phase in intake manifold, it is needed fuel pump to be capable of supplying with liquid state LPG from tank to fuel rail. Test results shows that discharged flow rate reduce about 25% of mixing propane 23% compared to butane 100%. The reason of discharged flow rate like this can be suspected the cavitations that are able to be occurred during working fluid drop below saturated vapor pressure. Cavitation is not only noisy but damages the pump impeller, shaft, and seal over time. Cavitation may also reduce pumping capacity. This study investigates the cavitation that can occur with measuring pressure in turbine type pump to improve discharged flow drop.