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"Untuk meningkatkan efektifitas penggunaan pupuk pada media tanam, dilakukan modifikasi terhadap pupuk sehingga menjadi pupuk lepas lambat. Dalam penelitian ini, pupuk NPK yang disintesis mengandung urea, amonium dihidrogen fosfat, dan kalium dihidrogen fosfat. Enkapsulasi pupuk NPK menggunakan hidrogel semi interpenetrating polymer network (semi-IPN) berbasis kitosan dan polistirena dilakukan dengan metode in situ loading dan post loading. Komposisi hidrogel kitosan-polistirena semi-IPN yang digunakan terdiri dari kitosan : stirena yaitu 80:20 dan menggunakan agen pengikat silang 5% asetaldehid 0,1 M. Karakterisasi pembentukan hidrogel kitosan-polistirena semi-IPN dan hidrogel kitosan dilakukan menggunakan spektorfotometri Fourier Tramsform Infrared (FTIR) dan mikroskop stereo. Uji pendahuluan seperti rasio sweliing dan derajat ikat silang juga diselidiki. Efisiensi laoding pupuk NPK dengan metode in situ loading mencapai 92.96% lebih besar daripada metode post loading yaitu 48.91% diukur dengan menggunakan spektrofotometer UV-Vis. Studi pelepasan pupuk NPK dari matriks hidrogel kitosan-polistirena semi-IPN dilakukan secara gravimetric dan spektrofotometri. Hasil uji pelepasan pupuk NPK yang terenkapsulasi dalam matriks hidrogel secara in situ loading lebih rendah dibandingkan secara post loading. Sifat lepas lambat dan kemampuan retensi air yang baik menunjukkan bahwa hidrogel kitosan-polistirena semi-IPN terenkapsulasi NPK berpotensi untuk aplikasi di bidang pertanian sebagai material pembawa pupuk.

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To improve the effectiveness of the use of fertilizer in the planting medium, the modification of the fertilizer was conducted to achieve a slow-release fertilizer. In this study, NPK fertilizer which contain urea, ammonium dihydrogen phosphate, and potassium dihydrogen phosphate was prepared. Encapsulation of NPK fertilizer using the semi-interpenetrating polymer network (semi-IPN) and polystyrene-based chitosan hydrogels was conducted using in situ loading and post-loading. The semi-IPN chitosan-polystyrene hydrogels were composed of chitosan: styrene monomer with 80:20 ratio and 5% acetaldehyde 0.1 M has been used as crosslinking agent. Characterization of semi-IPN chitosan-polystyrene hydrogels and chitosan hydrogels has been done using Fourier Transform Infrared (FTIR) Spectroscopy and stereo microscope. Preliminary test such as sweliing ratio and the degree of crosslinking was also investigated. Efficiency Laoding NPK fertilizer with in situ loading method was found to be 92.96% which was greater than the post-loading method which 48.91% . the efficiency loading wasmeasured by using UV-Vis spectrophotometer. Study of NPK fertilizer release from the chitosan hydrogel matrix semi-IPN-polystyrene was determined by gravimetric and spectrophotometric methods. Release of NPK fertilizer encapsulated within a hydrogel matrix by in situ loading was found to be lower than in post loading. Slow-release property and good water retention capability indicates that the chitosan-polystyrene hydrogel semi-IPN encapsulated NPK has apotential for applications in agriculture as a fertilizer carrier material."

"Metode semi-Interpenetrating Polymer Network (Semi-IPN) merupakan salah satu metode untuk mensintesis hidrogel. Pada metode semi-IPN, kitosan mengalami ikat silang dengan agen pengikat silang asetaldehida/ formaldehida/ glutaraldehida membentuk jaringan polimer kitosan terikat silang yang kemudian berinteraksi dengan polimer metil selulosa yang berbentuk linier. Umumnya derajat ikat silang dan rasio swelling hidrogel semi-IPN akan dipengaruhi oleh waktu reaksi, rasio komposisi kitosan-metil selulosa, dan jenis agen pengikat silang yaitu asetaldehida, formaldehida, dan glutaraldehida. Kemampuan swelling dan derajat ikat silang hidrogel kitosan-metil selulosa semi-IPN yang optimum didapat pada rasio kitosan/metil selulosa 60:40 (b/b), agen pengikat silang formaldehida 2% (b/b), dan waktu reaksi 3 jam yaitu persen rasio swelling 785,6 % dan derajat ikat silang 50,8 %. Hidrogel kitosan-metil selulosa dengan metode semi-IPN memiliki rasio swelling dan derajat ikat silang lebih besar dibandingkan dengan hidrogel kitosan nonkovalen. Karakterisasi hidrogel kitosan-metil selulosa semi-IPN dilakukan dengan instrumen Fourier Transfrom Infra Red (FTIR), Differential Scanning Calorimetry (DSC), dan Scanning Electron Microscope (SEM).

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Semi-Interpenetrating Polymer Network (semi-IPN) method is one of many methods which used to synthesize hydrogels. In semi-IPN method, chitosan was crosslinked with crosslinking agent acetaldehyde/ formaldehyde/ glutaraldehyde to form crosslinked chitosan polymer network that will interracts with methyl cellulose polymer which have linear form. In general, degree of crosslinking and swelling ratio of semi-IPN hydrogels were influenced by reaction time, composition ratio of chitosan-methyl cellulose, and crosslinking agent acetaldehyde, formaldehyde, and glutaraldehyde. Swelling ability and degree of crosslinking of chitosan-methyl cellulose hydrogel with semi-IPN method optimally reach at chitosan/methyl cellulose ratio 60:40 (b/b) with formaldehyde crosslinking agent in 3 hours reaction time is 785,6 % swelling ratio and 50,8 % degree of crosslinking. Chitosan-methyl cellulose hydrogel with semi-IPN method has higher swelling ratio and degree of crosslinking compared to noncovalent chitosan hydrogel. Characterization of chitosan-methyl cellulose semi-IPN hydrogel using Fourier Transfrom Infra Red (FTIR), Differential Scanning Calorimetry (DSC), dan Scanning Electron Microscope (SEM) instrument."

"Hidrogel semi-IPN merupakan suatu jaringan polimer yang memiliki kemampuan menyerap air yang besar dan cenderung mempertahankan strukturnya. Sintesis hidrogel kitosan-polistirena dengan metode semi-IPN dilakukan dengan dua tahap. Pada tahap pertama dibentuk jaringan kitosan terikat silang dengan menggunakan variasi agen pengikat silang yaitu, asetaldehida, formaldehida, dan glutaraldehida. Pada tahap kedua dilakukan polimerisasi polistirena di dalam jaringan kitosan terikat silang. Kondisi optimum dalam sintesis hidrogel kitosan-polistirena semi-IPN diperoleh dengan waktu reaksi polimerisasi polistirena selama 4 jam, komposisi kitosan dan stirena sebesar 80:20, dan agen pengikat silang asetaldehida. Pada kondisi optimum, hidrogel kitosan-polistirena semi-IPN memiliki sifat mekanik yang lebih baik dibandingkan dengan hidrogel kitosan dan mampu mempertahankan kemampuan swelling yang baik. Nilai rasio swelling dan derajat ikat silang hidrogel kitosan-polistirena semi-IPN pada kondisi optimum sebesar 751,2% dan 24,1% secara berurutan. Karakterisasi hidrogel kitosan-polistirena semi-IPN dilakukan dengan spektrofotometer Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC), dan Scanning Electron Microscope (SEM).

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Semi-IPN hydrogel is a polymer network that has a great ability to absorb water and tend to maintain its structure. Synthesis of hydrogel chitosan -polystyrene by semi-IPN method performed by two steps. First step, chitosan crosslinked network formed by using a variety of crosslinking agents, namely acetaldehyde, formaldehyde, and glutaraldehyde. In the second step, polymerization polystyrene in chitosan crosslinked network. The optimum conditions in synthesis of chitosan hydrogel-polystyrene semi-IPN is obtained with a reaction time of polymerization of polystyrene for 4 hours, composition of chitosan and styrene is 80:20, and the crosslinking agent is acetaldehyde. At the optimum conditions, hydrogel chitosan- polystyrene semi-IPN has better mechanical properties compared with the chitosan hydrogel and able to maintain good swelling capability. The value of swelling ratio and the degree of crosslinking of hydrogel chitosan-polystyrene semi-IPN in optimum condition are 751.2% and 24.1%. Characterization of hydrogel chitosan-polystyrene semi-IPN has been done by Spectrophotometer Fourier Transform Infrared (FTIR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscope (SEM)."

"Metode semi interpentrating polymer network (semi-IPN) merupakan metode yang digunakan untuk mensintesis hidrogel kitosan-poliNNDMAA. Pada metode ini, jaringan kitosan akan terikat silang dengan agen ikat silang lalu berinteraksi dengan jaringan polimer NNDMAA secara linear. Hasil sintesis memperlihatkan bahwa variasi penambahan monomer NNDMAA, agen ikat silang dan waktu reaksi akan menurunkan daya swelling dan meningkatkan derajat ikat silang. Rasio swelling dan derajat ikat silang optimum hidrogel kitosan poli NNDMAA semi-IPN terikat silang formaldehida didapatkan sebesar 545,64% dan 75,02% pada penambahan 25% berat NNDMAA dan waktu optimum pada 2 jam. Hidrogel kitosan poli NNDMAA semi-IPN terikat silang formaldehida memilki derajat ikat silang yang lebih besar jika dibandingkan terikat silang glutaraldehida maupun asetaldehida. Karakterisasi dilakukan dengan spektrofotometer Fourier Transform Infra Red (FTIR), Differential Scanning Calotimetry(DSC) dan Scanning Electron Microscope (SEM).

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Method semi interpentrating polymer network (semi-IPN) is a method used to synthesize the chitosan hydrogel-poliNNDMAA. In this method, chitosan will crosslinked with a crosslink agent then interacts with the polymer network NNDMAA linearly. Synthesis results show that the variation of the addition of monomer NNDMAA, crosslink agents and reaction time will reduce swelling and increase the degree of crosslink. Swelling ratio and the degree of crosslink optimum chitosan hydrogel poly NNDMAA crosslinked semi-IPN formaldehyde obtained by 545.64% and 75.02% on addition of 25% by weight NNDMAA and optimum time at 2 hours. Chitosan hydrogel poly NNDMAA crosslinked semi-IPN formaldehyde have the degree of cross belt larger than glutaraldehyde cross-linked or acetaldehyde. Characterization is done by spectrophotometer Fourier Transform Infra Red (FTIR), Differential Scanning Calotimetry (DSC) and Scanning Electron Microscope (SEM)."

"Metode IPN (Interpenetrating Polymer Network) baik semi maupun full IPNdapat digunakan untuk mensintesis hidrogel superabsorben (HSA) kitosan dan poli(N-vinil-kaprolaktam) (PNVCL) atau HSA kitosan-PNVCL. Pada metode full IPN jaringan polimer disintesis secara bertahap (sequential). Tahap pertama adalah sintesis jaringan polimer kitosan terikat silang asetaldehida dan homogenisasi dengan monomer N-vinil-kaprolaktam (NVCL) Tahap kedua adalah sintesis jaringan polimer PNVCL terikat silang N Nmetilenbisakrilamida (MBA) melalui polimerisasi radikal bebas monomer NVCL dengan inisiator amonium persulfat (APS) Hasil sintesis HSA kitosan-PNVCL full-IPN memiliki kekuatan struktur ikat silang dan kemampuan swelling yang baik Kekuatan struktur ikat silang meningkat dengan bertambahnya waktu reaksi, konsentrasi agen pengikat silang, inisiator, dan dipengaruhi rasio kitosan-PNVCL Kemampuan swelling HSA kitosan-PNVCL dengan kekuatan struktur ikat silang yang baik didapat pada rasio kitosan/PNVCL 70:30 (b/b %). HSA kitosan-PNVCL full-IPN memberikan persen derajat ikat silang yang tinggi (78,2%) dan kemampuan swelling yang baik (390,2%) Karakterisasi.

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The IPN (Interpenetrating Polymer Network) method, both semi and full IPN, can be used to synthesize chitosan and poly (N-vinyl-caprolactam) (PNVCL) superabsorbent hydrogels or HSA chitosan-PNVCL. In the full method of IPN polymer networks are synthesized sequentially. The first stage is the synthesis of crosslinked acetaldehyde chitosan polymer tissue and homogenization with N-vinyl-caprolactam (NVCL) monomer The second stage is synthesis of PNVCL polymer network bound by N Nmetilenbisakrilamida (MBA) through NVCL monomer free polymerization with ammonium persulfate (APS) initiator Synthesis of HSA chitosan-PNVCL full-IPN has crosslinked structure strength and good swelling ability The strength of crosslinking structure increases with increasing reaction time, concentration of crosslinking agent, initiator, and influenced by chitosan-PNVCL ratio Swelling ability of HSA chitosan-PNVCL with good cross-link structure strength is obtained at the chitosan / PNVCL ratio of 70:30 (b / b%). Full-IPN HSA chitosan-PNVCL gives a high percentage of crosslinking (78.2%) and good swelling ability (390.2%) Characterization Characterization."

"Metode semi-IPN (Interpenetrating Polymer Network) merupakan salah satu metode yang digunakan untuk mensintesis hidrogel superabsorben (HSA) kitosan dan poli(N-vinil-2-pirolidon) (PVP) atau kitosan-PVP. Pada metode semi-IPN, kitosan mengalami reaksi ikat silang dengan asetaldehida membentuk jaringan polimer kitosan terikat silang yang berinteraksi dengan polimer PVP linier. Hasil sintesis HSA kitosan-PVP semi-IPN diharapkan memiliki kekuatan mekanik dan kemampuan swelling yang baik. Kekuatan struktur ikat silang akan meningkat sampai mencapai titik optimum seiring bertambahnya waktu reaksi, konsentrasi agen pengikat silang dan pengaruh rasio kitosan-PVP. Kemampuan swelling HSA kitosan-PVP semi-IPN dengan kekuatan struktur ikat silang yang optimum didapat pada rasio kitosan/PVP 70:30 (b/b%) dengan konsentrasi asetaldehida 2 % dan waktu reaksi 3 jam. HSA kitosan-PVP semi-IPN optimum memberikan persen derajat ikat silang 55,9 % dan kemampuan swelling yang cukup tinggi yaitu 475,6 %. Karakterisasi HSA dilakukan dengan spektrofotometer Fourier Transform Infra Red (FTIR), analisis termal (DSC) dan analisis morfologi (SEM).

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Semi-IPN (Interpenetrating Polymer Network) is one method which can be used to synthesis the superabsorben hydrogel (HSA) of chitosan and poly (N-vinyl-2-pyrrolidone) (PVP) or HSA chitosan-PVP. In the semi-IPN method, chitosan crosslinked with acetaldehyde forming a crosslinked polymer network of chitosan which interacts with linier polymer of PVP. The result of synthesis between HSA chitosan ? PVP semi-IPN is expected to have a good mechanical strength and swelling capability. The strength of crosslinking structure will raise up to its optimum point along with the increase of reaction time, concentration of crosslinker and the influence of chitosan-PVP ratio. Swelling cability of HSA chitosan-PVP semi-IPN with optimum strength of crosslinking structure is obtained in the ratio of chitosan/PVP at 70:30 (w/w %) with 2% acetaldehyde concentration and 3 hours reaction time. The optimum HSA chitosan- PVP semi-IPN provides 55,9% degree of crosslinking and high enough swelling ability at 475,6%. Characterization of HSA is conducted by Fourier Transform Infra Red (FTIR) spectrometer, thermal analysis (DSC) and morphological analysis (SEM)."

"Material polimer untuk menyusun hidrogel harus dapat mengembang (swell) dan mempertahankan fraksi air pada strukturnya, namun tidak larut dalam air. Polimer alami memiliki gugus fungsi yang dapat menjadi pusat aktif reaksi dimana dapat dilakukan modifikasi untuk menghasilkan suatu polimer dengan karakteristik yang lebih baik. Kitosan merupakan polimer alami yang memiliki kekuatan struktur yang kurang dibandingkan kemampuan swelling. Sintesis hidrogel kitosan dengan metode full interpenetrating polymer network (IPN) dapat meningkatkan kekuatan struktur melalui ikat silang. Tahap pertama adalah sintesis jaringan polimer kitosan terikat silang asetaldehida. Tahap kedua adalah sintesis jaringan polimer PNVCL terikat silang N, N?-metilenbisakrilamida (MBA) melalui polimerisasi radikal bebas monomer NVCL dengan inisiator amonium persulfat (APS). Variasi waktu, rasio kitosan-PNVCL, konsentrasi agen pengikat silang, dan konsentrasi inisiator dipelajari untuk mengetahui kondisi optimum. Kondisi optimum diperoleh pada reaksi 2 jam dengan rasio kitosan/NVCL 90:10 (b/b %), konsentrasi MBA 0,5%, dan konsentrasi APS 3%. HSA kitosan-PNVCL memberikan rasio swelling 380,66% dan derajat ikat silang 60,85%. Karakterisasi HSA dilakukan dengan spektrofotometer Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA), Scanning Electron Microscope (SEM), dan X-Ray Diffraction (XRD).

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Polymer material used for hydrogel should have the ability to swell and to keep water molecules in its structure without dissolving in water. Natural polymers has functional groups which can perform as active sites in modification to produce polymer with better characteristic. Chitosan is a natural polymer which has good swelling ability but lack of structural strength. Synthesis of chitosan hydrogel by interpenetrating polymer network (IPN) will increase its strength through crosslinking. In this research, the first step of modification was the synthesis of chitosan polymer network crosslinked by acetaldehyde. The next step was the synthesis of PNVCL polymer network crosslinked by N,N-methylbisacrylamide (MBA) through free radical polymerization of NVCL monomer with ammonium persulfat (APS) as the initiatior. Optimum reaction time, chitosan/PNVCL ratio (w/w %), concentration of crosslinker agent, and concentration of initiator had been observed. The optimum conditions were obtained as followed: 2 hours reaction, the ratio chitosan/PNVCL of 90:10 (w/w %), %-w MBA concentration of 0,5%, and APS concentration of 3%. The swelling ratio of the hydrogel was 380,66% while the crosslinking degree was 60,85%. Fourier transfor infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Thermogravimetric analysis (TGA), Scanning Electron Microscope (SEM), and X-Ray diffraction (XRD) were used for the characterization of the hydrogel."

"Hidrogel kitosan termodifikasi interpenetrating polymer network berhasil disintesis yaitu kitosan, kitosan terikat-silang, kitosan-poly N-vinyl-2-pyrrolidone semi-IPN dan kitosan-N-vinyl-2-pyrrolidone full-IPN. Hidrogel kitosan termodifikasi interpenetrating polymer network diloadingkan captopril. Metode loading obat ke dalam matriks hidrogel yaitu in situ and post loading. Konsentrasi obat yang terloading ke dalam matriks hidrogel divariasikan yaitu 12.5 mg; 25 mg; 37.5 mg and 50 mg. Loading obat dengan metode in situ loading dilakukan dengan menambahkan obat sebelum penambahan agen pengikat silang, sedangkan post loading dilakukan dengan mengimersikan hidrogel ke dalam larutan obat. hidrogel yang terloading obat disebut mikrokapsul. Efisiensi enkapsulasi ditentukan dengan mengimeriskan mikrokapsul ke dalam larutan buffer pH 7,4. Hidrogel dikarakterisasi dilakukan dengan penentuan derajat ikat-silang , rasio swelling , spketrofotometer FTIR dan mikroskop stereo. Derajat ikat-silang dari kitosan, kitosan terikat-silang, kitosan-poly N-vinyl-2-pyrrolidone semi-IPN dan kitosan-N-vinyl-2-pyrrolidone full-IPN adalah 51.62 , 54.65 , 70.15 dan 77.23 . rasio swelling dari kitosan, kitosan terikat-silang, kitosan-poly N-vinyl-2-pyrrolidone semi-IPN dan kitosan-N-vinyl-2-pyrrolidone full-IPN adalah 4412.88 , 2118.01 , 1748.65 dan 441,38 selama 1 jam. Konsentrasi optimum loading obat 12.5 mg and 25 mg. Hidrogel terloading obat disebut mikrokapsul. Pelepasan mikrokapsul captopril in situ and post loading selama 12 jam menunjukkan pelepasan lambat. Profil pelepasan obat pada pH 1,2 dari matriks hidrogel kitosan dan kitosan terikat-silang in situ loading secara difusi dan degradasi, sedangkan semi-IPN and full-IPN in situ loading secara difusi, pada pH 7,4 pelepasan obat mikrokapsul in situ loading secara difusi. Profil pelepasan obat dari mikrokaspul post loading pada pH 1,2 dan 7,4 terjadi secara difusi diikuti erosi matriks hidrogel.

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Preparation chitosan interpenetrating polymer network modified hydrogels have been successfuly. It were chitosan, chitosan crosslinked, semi IPN chitosan poly N vinyl 2 pyrrolidone and full IPN chitosan N vinyl 2 pyrrolidone. These hydrogels were loaded by captropil. Captopril was loaded within hydrogel matrix using both in situ and post loading method. Concentration variation of drug loaded were 12.5 mg 25 mg 37.5 mg and 50 mg. At in situ loading, drug was loaded during synthesis of hydrogel before the addition of crosslinking agent, while at post loading method hydrogels were immersed into a drug solution. This hydrogels loaded captopril called microcapsul. Encapsulation efficiency was evaluated in pH 7.4 solution. Hydrogels characterization including crosslinking degree , swelling ratio , FTIR spectrophotometer and stereo microscope. Crosslinking degree of chitosan, chitosan crosslinked, semi IPN and full IPN hydrogels were found to be 51.62 , 54.65 , 70.15 and 77.23 respectively. Swelling ratio of chitosan, chitosan crosslinked, semi IPN and full IPN hydrogels were 4412.88 , 2118.01 , 1748.65 and 441,38 for 1 hour, respectively. The optimum drug concenration was 12.5 mg and 25 mg. Hydrogels loading drug called microcapsule. Release of captopril microcapsules by in situ and post loading shown that slow release for 12 hour. Profile of release drug from chitosan and chitosan crosslinked hydrogels by in situ loading at pH 1,2 through difussion and degradation, while semi IPN and full IPN hydrogels by in situ loading at pH 1,2 through difussion. At pH 7,4 of profile of release drug from microcapsules through difussion. Profile of release drug at pH 1,2 and 7,4 from microcapsules by post loading through difussion followed erotion."

"ABSTRAKCaptopril merupakan antihipertensif golongan angiotensin converting enzyme inhibitor ACEI yang banyak digunakan untuk mengontrol tekanan darah sekaligus mengurangi penyakit jantung. Suatu penelitian melaporkan bahwa captopril bekerja dengan menginhibisi konversi enzim ACE I menjadi ACE II, mengurangi plasma angiotensin II dan level aldosteron, meningkatkan plasma renin, dan menghasilkan penurunan tekanan darah yang signifikan bagi penderita hipertensi. Dibalik manfaatnya yang baik bagi kesehatan, captopril diketahui memiliki waktu paruh biologis yang singkat dalam tubuh dan memerlukan frekuensi administrasi yang berulang. Suatu sistem penghantaran obat yang tepat diperlukan untuk memodifikasi pelepasan captopril dalam tubuh. Salah satunya menggunakan hidrogel berbasis kitosan yang terikat silang poli N-vinil-2-pirolidon atau PVP melalui interpenetrating polymer network IPN . Meskipun efisiensi kapsulasi dan pelepasannya secara umum telah diteliti, informasi tentang kinetika swelling matriks hidrogel dan mekanisme pelepasannya belum diketahui. Penelitian ini akan berfokus pada kedua hal tersebut. Sebagai perbandingan, hidrogel yang akan diteliti meliputi hidrogel kitosan nonkovalen, hidrogel kitosan terikat silang, hidrogel kitosan-PVP semi-IPN, dan hidrogel kitosan-NVP full-IPN. Kinetika swelling akan ditentukan melalui analisis gravimetri mengikuti hukum laju pseudo-orde pertama dan hukum laju pseudo-orde kedua. Mekanisme pelepasan akan ditentukan melalui persamaan laju orde nol, orde satu, model Higuci, dan model Korsemeyer-Peppas.

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ABSTRACTCaptopril is an antihypertensive class of angiotensin converting enzyme inhibitors ACEI that is widely used to control blood pressure disease. A study reported that captopril works by inhibiting the conversion of the ACE I enzyme to ACE II, reducing plasma angiotensin II and aldosterone levels, increasing plasma renin, and generating a significant drop in blood pressure for hypertensive patients. Behind its good health benefits, captopril is known to have short biological half lives in the body and requires repeated administration frequencies. An appropriate drug delivery system is needed to overcome the release of captopril in the body. One way to achieved it is by using a crosslinked poly N vinyl 2 pyrrolidone chitosan based hydrogel or PVP via an interpenetrating polymer network IPN . However, information about the kinetics of the swelling of the hydrogel matrix and its release mechanism is unknown. This research will focus in its cases. In comparison, the hydrogels to be studied are noncovalent hydrogel, cross linked hydrogel, semi IPN chitosan PVP hydrogel, and full IPN chitosan NVP hydrogel. Kinetics of swelling will be determined by the gravimetric analysis of pseudo first order and the pseudo second order rate law. The mechanism will be determined by the zero order rate equation, first order, Higuci model, and Korsemeyer Peppas model."

"Metode semi-Interpenetrating Polymer Network (semi-IPN) dapat digunakan untuk mensintesis hidrogel. Pada metode ini, jaringan kitosan terikat silang formaldehida akan berinteraksi dengan poli(N-vinil pirolidon) linear. Secara umum, rasio sweling dan derajat ikat silang hidrogel semi-IPN dipengaruhi oleh komposisi kitosan-PVP, konsentrasi formaldehida, dan waktu reaksi. Rasio swelling dan derajat ikat silang dari hidrogel kitosan-poli(N-vinil pirolidon) semi-IPN didapatkan sebesar 553,70% dan 58,82% pada rasio kitosan-poli(N-vinil pirolidon) 70:30 (%b/b), konsentrasi formaldehida 2% (%b/b), dan waktu reaksi 3 jam. Hidrogel kitosan-poli(N-vinil pirolidon) semi-IPN menunjukkan penurunan rasio swelling dan peningkatan derajat ikat silang dibandingkan hidrogel kitosan nonkovalen.

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Semi-Interpenetrating Polymer Network (semi-IPN) method was used to synthesize hydrogel. In this method, chitosan was crosslinked with formaldehyde and blended with Poly(N-vinyl pyrrolidone) to form crosslinked chitosan network that interracts with linear polymer of Poly(N-vinyl pyrrolidone). Generally, swelling ratio and degree of crosslinking of semi-IPN hydrogel were influenced by Poly(N-vinyl pyrrolidone) amount, concentration of formaldehyde, and reaction time. Swelling ratio and degree of crosslinking of semi-IPN hydrogel was obtained at 553,70% and 58,82% in the ratio of chitosan- Poly(N-vinyl pyrrolidone) 70:30 (%w/w), formaldehyde concentration of 2%, and 3 hours of reaction time. Semi-IPN hydrogel of chitosan-Poly(N-vinyl pyrrolidone) has lower swelling ratio and higher degree of crosslinking compared to hydrogel of chitosan."