Release rates from semi-crystalline polymer microcapsules formed by interfacial polycondensation

Yadav, Shivesh; Khilar, Kartic C.; Suresh, Akkihebbal K.

doi:10.1016/s0376-7388(96)00171-8

Cited by 57 publications

(27 citation statements)

References 7 publications

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“…For controlled release applications of starch, the plasticiser trend is interesting because of the influence of crystallinity on the release behaviour. Crystallinity slows down release and is needed for capsule stability, but too high crystallinity causes capsules to crack when swelling or induces micropores in the capsule, increasing release (Ispas-Szabo, Ravenelle, Hassan, Preda, & Mateescu, 2000;Miyajima, Koshika, Okada, Ikeda, & Nishimura, 1997;Yadav, Khilar, & Suresh, 1997).…”

Section: Resultsmentioning

confidence: 99%

The influence of various small plasticisers and malto-oligosaccharides on the retrogradation of (partly) gelatinised starch

Smits

Kruiskamp

Soest³

et al. 2003

Carbohydrate Polymers

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Ageing of gelatinised and partly gelatinised potato starch and wheat starch were investigated in the presence of plasticisers with increasing size and number of OH groups (ethylene glycol, glycerol, threitol, xylitol, glucose, and for potato starch also maltose). The influences of these plasticisers and of granular remnants (ghosts) on recrystallisation were determined by using X-ray diffraction. Recrystallisation of potato starch samples in the presence of plasticisers resulted in crystallinity indices of ,0.5. The largest reduction in potato starch recrystallisation is found for threitol (4 OH) and xylitol (5 OH). In the plasticiser range examined, the crystallisation inducing effect of granular potato starch remnants is reduced better when the plasticiser contains more OH groups. Wheat starch recrystallises to a lesser extent than potato starch, resulting in crystallinity indices of , 0.4. The results for wheat starch do not show clear trends for the influences of plasticiser size and of ghosts. The difference in behaviour of the two starches is probably caused by wheat starch having shorter amylopectin chains. Resulting from these shorter amylopectin chains, the remaining structure in wheat starch ghosts may resemble A-type crystallinity, making it more difficult to form B-type crystals. Alternatively, the trends as found for potato starch may occur, but are less manifest for wheat starch, due to the lower total extent of recrystallisation. Solid state CP/MAS NMR spectra of the wheat starch samples containing ethylene glycol were obtained, in order to compare completely and partly gelatinised systems. The spectra were identical, confirming that the ghost structures do not influence wheat starch recrystallisation. Apparently, wheat starch ghosts do not act as nuclei for crystallisation.Similarly, the influence of various malto-oligosaccharides in combination with granular remnants (ghosts) was investigated on wheat starch ageing. Gelatinised and partly gelatinised wheat starch were plasticised with maltose, maltotriose, maltotetraose, maltopentaose or maltohexaose. This resulted in crystallinity indices of , 0.2, with the largest reduction in recrystallisation for maltotriose and maltotetraose. No trend was found for the influence of ghosts. The presence of ghosts did not influence the 13 C solid state HP/DEC NMR spectra. Less recrystallisation took place than with the previously mentioned smaller plasticisers that resulted in crystallinity indices of ,0.4. The finding that maltose was able to reduce retrogradation better than glucose could be of practical importance. q

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Section: Resultsmentioning

confidence: 99%

The influence of various small plasticisers and malto-oligosaccharides on the retrogradation of (partly) gelatinised starch

Smits

Kruiskamp

Soest³

et al. 2003

Carbohydrate Polymers

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“…Oil nanocapsules, whether in aqueous or solid form, are protected by a thin polymeric wall, which provides protection, permeability, and controlled release of the drug. Different methods and technologies can be applied to create polymeric nanocapsules such as a physicochemical process using a preformed polymer (5)(6)(7)(8). Interfacial polycondensation is a chemical process based on a polymerization reaction often used for the preparation of microcapsules (9).…”

Section: Introductionmentioning

confidence: 99%

Preparation of Polyamide Nanocapsules of Aloe vera L. Delivery with In Vivo Studies

Esmaeili

Ebrahimzadeh

2014

AAPS PharmSciTech

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Abstract. Aloe vera is the oldest medicinal plant ever known and the most applied medicinal plant worldwide. The purpose of this study was to prepare polyamide nanocapsules containing A. vera L. by an emulsion diffusion technique with in vivo studies. Diethyletriamine (DETA) was used as the encapsulating polymer with acetone ethyl acetate and dimethyl sulfoxide (DMSO) as the organic solvents and Tween and gelatin in water as the stabilizers. Sebacoyl chloride (SC) monomer, A. vera L. extract, and olive oil were mixed with the acetone and then water containing DETA monomer was added to the solution using a magnetic stirrer. Finally, the acetone was removed under vacuum, and nanocapsules were obtained using a freeze drier. This study showed that the size of the nanocapsule depends on a variety of factors such as the ratio of polymer to oil, the concentration of polymers, and the plant extract. The first sample is without surfactant and the size of nanocapsules in the sample is 115 nm. By adding surfactant, nanocapsules size was reduced to 96 nm. Nanocapsules containing A. vera were administered to rats and the effects were compared with a normal control group. The results showed that in the A. vera group, the effect is higher. The nanocapsules were identified by scanning electron microscopy (SEM), zeta potential sizer (ZPS), and Fourier-transform infrared spectroscopy (FT-IR).KEY WORDS: Aloe vera L.; in vivo; medicinal plant; nanocapsule; polyamide nanocapsule.

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“…In studies on water-loaded microcapsules of different homopolymers, the permeability of the microcapsule membranes towards the solute has been found to be dependent on capsule size, chemical structure of polymers constituting the membranes and solutes, and composition (in the case of homopolymer mixtures) [14]. With polyurea microcapsules, a variation in permeability by an order of magnitude could be achieved by varying the crystallinity of the polyurea [15]. The reaction kinetics seems to be important in controlling the crystallinity-there being a rough inverse correlation between rate and crystallinity [5,9,16].…”

Section: Introductionmentioning

confidence: 99%

An experimental study of polyurea membrane formation by interfacial polycondensation

Wagh

Dhumal

Suresh

2009

Journal of Membrane Science

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Release rates from semi-crystalline polymer microcapsules formed by interfacial polycondensation

Cited by 57 publications

References 7 publications

The influence of various small plasticisers and malto-oligosaccharides on the retrogradation of (partly) gelatinised starch

The influence of various small plasticisers and malto-oligosaccharides on the retrogradation of (partly) gelatinised starch

Preparation of Polyamide Nanocapsules of Aloe vera L. Delivery with In Vivo Studies

An experimental study of polyurea membrane formation by interfacial polycondensation

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