D. Darwis
Center for Isotopes and Radiation Application, National Nuclear Energy Agency, Indonesia

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Role of Radiation Processing in Production of Hydrogels For Medical Applications Darwis, D.
Atom Indonesia Vol 35, No 2 (2009): July 2009
Publisher : PPIKSN-BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (394.415 KB) | DOI: 10.17146/aij.2009.12

Abstract

Recently, hydrophilic polymer gel (hydrogel) for application in medical fields has attracted much attention of researchers due to its unique properties which can resemble human living organs. Wound dressing, contact lenses and drug delivery system are among their applications in medical field. High energy radiation especially gamma ray and electron beam is often used for synthesis and modification of hydrogel. Through radiation crosslinking and or grafting process, hydrogel with specialty properties for specific application can be made. The advantage of radiation synthesized hydrogel over conventional methods is very pure products are obtained since the present of chemical initiators are not required; The preparation of sample does not require special sterile production rooms but still enables to obtain a sterile product; The irradiation process is easily controlled; Synthetis of new polymers and bulk or surface modification of commercial products can be accomplished with additional advantage of possibility of a concurrent sterilization. The future prospect of hydrogel seems to be in tissue engineering and diagnostic fields. Received: 27 February 2009; Reevised: 27 May 2009; Accepted: 16 June 2009
In-vitro Degradation Behaviour of Irradiated Bacterial Cellulose Membrane Darwis, D.; Khusniya, T.; Hardiningsih, L.; Nurlidar, F.; Winarno, H.
Atom Indonesia Vol 38, No 2 (2012): August 2012
Publisher : PPIKSN-BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (2680.595 KB) | DOI: 10.17146/aij.2012.164

Abstract

Bacterial cellulose membrane synthesized by Acetobacter xylinum in coconut water medium has potential application for Guided bone Regeneration. However, this membrane may not meet some application requirements due to its low biodegradation properties. In this paper, incorporation of gamma irradiation into the membrane is a developed strategy to increase its biodegradability properties. The in–vitro degradation study in synthetic body fluid (SBF) of the irradiated membrane has been analyzed during periods of 6 months by means of weight loss, mechanical properties and scanning electron microscopy observation compared to that the un-irradiated one. The result showed that weight loss of irradiated membrane with 25 kGy and 50 kGy and immersed in SBF solution for 6 months reached 18% and 25% respectively. While un-irradiated membrane did not give significant weight loss. Tensile strength of membranes decreases with increasing of irradiation dose and further decreases in tensile strength is observed when irradiated membrane was followed by immersion in SBF solution. Microscope electron image of cellulose membranes shows that un-irradiated bacterial cellulose membrane consists of dense ultrafine fibril network structures, while irradiation result in cleavage of fibrils network of cellulose. The fibrils network become loosely after irradiated membrane immersed in SBF solution due to released of small molecular weight carbohydrates formed during by irradiation from the structure. Received: 05 December 2011; Revised: 24 September 2012; Accepted: 29 August 2012
The Effect of Gamma Radiation on Microbial Content and Curcuminoids of Curcuma amada Roxb. Rhizomes Rahayu, D.P.; Saputri, F.C.; Darwis, D.
Atom Indonesia ARTICLE IN PRESS
Publisher : PPIKSN-BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (37.339 KB) | DOI: 10.17146/aij.2016.480

Abstract

The microbial contamination in the rhizomes of medicinal plants including Curcuma amada rhizomes is generally high. This due to the fact that rhizomes are the bottom parts that grow in the soil. Based on the Regulation of Head of the Indonesian National Agency of Drug and Food Control Number HK.00.06.1.52.4011, the limits of microbial contamination in herbal/medicinal plants are 106 cfu/g for the total microbial and 2×104 cfu/g for the total yeast and mold. Gamma irradiation is one of the methods to reduce microbial contamination in medicinal plants. In this research, the effectiveness of gamma irradiation in microbial reduction and its effects to curcuminoid contents was determined by irradiating Curcuma amada rhizomes at doses of 5 and 10 kGy. The initial contamination in this rhizome was 8.78×107 cfu/g and 5×101 cfu/g for the total microbial and for the total yeast and mould, respectively. The result indicates that at 5 kGy, the microbial contamination and the mould and yeast contamination were reduced from 8.78×107 cfu/g and 5×101 cfu/g to 1.39×104 cfu/g and under 1×101 cfu/g, respectively. Meanwhile the comparison of curcuminoids between the irradiated and non irradiated samples was performed by HPLC method and was found to actually increase from 0.26 % to 0.36 % after the 5-kGy irradiation. It can be concluded that an irradiation dose of 5 kGy is effective to reduce the content of microorganisms without lowering curcuminoids. Gamma radiation could be used as decontamination method in medicinal plants.
TRANSFORMATION OF RICINOLEIC OF CASTOR OIL INTO LINOLEIC (OMEGA-6) AND CONJUGATED LINOLEIC ACID BY DEHYDRATION Sitorus, Marham; Ibrahim, S.; Nurdin, H.; Darwis, D.
Indonesian Journal of Chemistry Vol 9, No 2 (2009)
Publisher : Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (268.997 KB) | DOI: 10.22146/ijc.21543

Abstract

The ricinoleic of Castor Oil was dehydrated by various dehydrator agent (P2O5, K2CO3, H3PO4, NaHSO4, Al2O3, molecular sieve and activated bentonite at 450 °C - HCl) on the same condition (150 °C, mol ratio 1:1 and 2 hours ). The compositions of Refined Ricinus Castor Oil as starting material were : 0.92% palmitic , 5.56% linoleic , 4.07% octadecanoic , 1.22% stearic and 85.06% ricinoleic. The spesific wave number of IR was bandwith 3411 cm-1 caused of hydroxyl (-OH) group of ricinoleic at C-12 as main component. The product was Dehydrated Castor Oil (DCO) mixed of linoleic (omega 6) [C18 : 2 (9,12)] and Conjugated Linoleic Acid (CLA) [C18: 2 (9,11)]. The best dehydrator was P2O5 based on three parameters were : Free Fatty Acid (FFA) nearly the same (1.855% of Castor oil and 2.139% of DCO), the most increased of Iodium value (49.860 mg/g of Castor oil in to 63.090 mg/g of DCO), and the most decresed of hydroxyl number (28.27 mg of Castor oil in to 17.75 mg/g of DCO). To optimized the dehydration was done by various number of P2O5 (3g, 5g and 7g), tempereture (room, 100 °C and 150 °C) and time (2h, 2.5h, 3h, and 3.5h). The optimal conditon of dehydration was not found yet. Some of sugestted or idea for dehydration were: dehydration must be done by base or netral, non oxydator dehydrator, mol ratio 1:1, temperature (100-150 °C) and 2-3.5 h. Based on GC-MS the best DCO (7g P2O5, 150 °C and 3.5 h) were showed that the decrease of ricinoleic 14.13% (85.08% of Castor Oil in to 70.93% of DCO), increased linoleic 2.09% (5.56 of Castor oil in to 7.65% of DCO) and conducted of 9.09% CLA. Some new peaks between linoleic and ricinoleic are maybe isomers of linoleic and CLA. The wave number of cunjugated alkene (C=C) (1666.3 cm-1) of IR spectra of DCO together with GC-MS chromatograms to indicated that linoleic and CLA were conducted.   Keywords: castor oil, risinoleic, dehydration, omega 6 dan CLA