Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MICROWAVES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed2003

The cost of microwave endometrial ablation under different anaesthetic and clinical settings.

OBJECTIVE: To compare the costs of microwave endometrial ablation under local anaesthetic and general anaesthetic in an operating theatre and to estimate the cost of performing treatment under local anaesthetic in a dedicated clinic setting. DESIGN: The costing study was undertaken alongside a randomised controlled trial comparing the acceptability of microwave endometrial ablation using local versus general anaesthetic in a theatre setting. SETTING: Department of Gynaecology, Aberdeen Royal Infirmary, Scotland. SAMPLES: One hundred and twenty-seven women undergoing microwave endometrial ablation who had been randomly allocated to general or local anaesthetic. METHODS: Health and non-health service resource use was recorded prospectively. Data on resource use were combined with unit costs estimated using standardised methods to determine the cost per patient for microwave endometrial ablation under local or general anaesthetic in theatre. A model was developed to estimate the health service cost of microwave endometrial ablation under local anaesthetic in a clinic setting. MAIN OUTCOME MEASURES: Health and non-health service costs. RESULTS: There was little difference in cost when treatments were performed under local or general anaesthetic in theatre. The median health and non-health cost of microwave endometrial ablation was 440 pounds and 120 pounds, respectively, under general anaesthetic and 428 pounds and 125 pounds per women under local anaesthetic. The health service cost of microwave endometrial ablation using local anaesthetic in a clinic setting was estimated to be 432 pounds per treatment; however, this varied from 389 pounds to 491 pounds in the sensitivity analysis. CONCLUSION: There are minimal cost savings to the patient or health service from using local rather than general anaesthetic for microwave endometrial ablation in a theatre setting. Cost modelling suggests that in a clinic setting microwave endometrial ablation has a similar cost to theatre based treatment once re-admissions for treatment under general anaesthetic are considered. Sensitivity analysis indicated that these findings were sensitive to assumptions in the model.

Anesthesia, General↗
PubMed2004

Low power microwave radiation inhibits the proliferation of rabbit lens epithelial cells by upregulating P27Kip1 expression.

PURPOSE: The goal of this study was to examine the effects of low power microwave radiation (<10 mW/cm2) on the proliferation of cultured rabbit lens epithelial cells (RLEC). METHODS: Cultured RLEC were exposed to continuous microwave radiation at a frequency of 2,450 MHz and power densities of 0.10, 0.25, 0.50, 1.00, and 2.00 mW/cm2 for 8 h. Cell morphologic changes were observed under a phase-contrast microscope. Cell viability was measured using the MTT assay and cell cycle analysis was measured using flow cytometry. After exposure to 2.00 mW/cm2 microwave radiation for 4, 6, and 8 h, the expression of cell cycle-regulatory proteins, P21WAF1 and P27Kip1, was examined using western blot analysis. Finally, the levels of P21WAF1 and P27Kip1 mRNA were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: After 8 h of radiation treatment, cells treated with 0.50, 1.00, and 2.00 mW/cm2 microwave radiation exhibited decreased cell viability, increased cell condensation and an inhibition of DNA synthesis. RLEC showed significant G0/G1 arrest. No obvious changes could be detected in the 0.10 and 0.25 mW/cm2 microwave treatment groups. Protein expression of P27Kip1 was markedly increased after microwave radiation. However, the mRNA levels were unchanged. On the other hand, there were no detectable differences in P21WAF1 protein expression and mRNA levels between microwave treatment and control groups. CONCLUSIONS: This study suggests that low power microwave radiation higher than 0.50 mW/cm2 can inhibit lens epithelial cell proliferation, and increase the expression of P27Kip1. These effects may account for the decline of lens epithelial proliferation after exposure to microwave radiation.

Animals↗
PubMed1980

[Microwave radiation sources requiring periodic or sporadic hygienic control].

Throughout 1972--1978 measurements of dissipated microwave radiation in the environment of about 600 microwave apparatus of various types were taken. In the environment of the apparatus dissipated microwave radiation was found of values of the safety, dangerous, warning and intermediate zones, respectively. In the hitherto taken measurements many microwave devices have been observed, in whose environment no dissipated microwave radiation but low values in the safety zone have been found. These are e.g. such devices as sets of microwave laboratory systems of a very low power, microwave block in EPR spectrometers and NEC radio link transmitters. Our investigations indicate that for those devices sporadic hygienic control of electromagnetic field would be sufficient. Different types of microwave sources categorized into two groups according to the values of power density of dissipated microwave radiation near those sources have been presented.

Diathermy↗
PubMed2005

Microwave-enhanced reaction rates for nanoparticle synthesis.

Microwave reactor methodologies are unique in their ability to be scaled-up without suffering thermal gradient effects, providing a potentially industrially important improvement in nanocrystal synthetic methodology over convective methods. Synthesis of high-quality, near monodispersity nanoscale InGaP, InP, and CdSe have been prepared via direct microwave heating of the molecular precursors rather than convective heating of the solvent. Microwave dielectric heating not only enhances the rate of formation, it also enhances the material quality and size distributions. The reaction rates are influenced by the microwave field and by additives. The final quality of the microwave-generated materials depends on the reactant choice, the applied power, the reaction time, and temperature. CdSe nanocrystals prepared in the presence of a strong microwave absorber exhibit sharp excitonic features and a QY of 68% for microwave-grown materials. InGaP and InP are rapidly formed at 280 degrees C in minutes, yielding clean reactions and monodisperse size distributions that require no size-selective precipitation and result in the highest out of batch quantum efficiency reported to date of 15% prior to chemical etching. The use of microwave (MW) methodology is readily scalable to larger reaction volumes, allows faster reaction times, removes the need for high-temperature injection, and suggests a specific microwave effect may be present in these reactions.

Journal Article↗
PubMed2004

Changes in human EEG caused by low level modulated microwave stimulation.

This study focuses on the effect of low level microwave radiation on human EEG alpha and theta rhythms. During the experiment, 20 healthy volunteers were exposed to a 450 MHz microwaves with 7 Hz on-off modulation. The field power density at the scalp was 0.16 mW/cm2. Signals from the following EEG channels were used: FP1, FP2, P3, P4, T3, T4, O1, and O2. The experimental protocol consisted of one cycle of short term photic and ten cycles of the repetitive microwave stimulation. The changes caused by photic as well as microwave stimulation were more regular on the alpha rhythm. In the majority of cases, photic stimulation caused changes in the EEG energy level in the occipital and microwave stimulation in the frontal region. Our experimental results demonstrated that microwave stimulation effects became apparent, starting from the third stimulation cycle. Changes varied strongly from subject to subject. Therefore, photic and microwave exposure did not cause statistically significant changes in the EEG activity level for the whole group. For some subjects, clear tendencies of changes in microwave on-off cycles were noticeable.

Action Potentials↗
PubMed2005

Acute effects of pulsed microwaves and 3-nitropropionic acid on neuronal ultrastructure in the rat caudate-putamen.

Ultrastructure of the medium sized "spiny" neuron in rat dorsal-lateral caudate-putamen was assessed after administration of 3-nitropropionic acid (3-NP) and exposure to pulsed microwaves. Sprague-Dawley male rats were given two daily intraperitoneal doses of 0 or 10 mg/kg 3-NP and 1.5 h after each dose were exposed to microwave radiation at a whole body averaged specific absorption rate (SAR) of 0 (sham exposure), 0.6, or 6 W/kg for 30 min. Microwave exposure consisted of 1.25 GHz radiation delivered as 5.9 micros pulses with repetition frequency 10 Hz. Tissue samples taken 2-3 h after the second sham or microwave exposure showed no injury with light microscope methods. Blinded qualitative assessment of ultrastructure of randomly selected neurons from the same samples did reveal differences. Subsequent detailed, quantitative measurements showed that, when followed by sham exposure, administration of 3-NP significantly increased endoplasmic reticulum (ER) intracisternal width, ER area density, and nuclear envelope thickness. Microwave exposure at 6 W/kg alone also significantly increased these measures. Exposure of 3-NP treated animals at 6 W/kg significantly increased effects of 3-NP on ultrastructure. Although exposure at 0.6 W/kg alone did not affect ultrastructure measures, exposure of 3-NP treated animals at 0.6 W/kg reduced the effects of 3-NP. We concluded that 3-NP changed neuronal ultrastructure and that the microwave exposures used here changed neuronal ultrastructure in ways that depended on microwave SAR and neuron metabolic status. The apparent cancellation of 3-NP induced changes by exposure to pulsed microwaves at 0.6 W/kg indicated the possibility that such exposure can protect against the effects of mitochondrial toxins on the nervous system.

Acute Disease↗
PubMed1983

Effects of microwave exposure on the hamster immune system. II. Peritoneal macrophage function.

Acute exposure to hamsters to microwave energy (2.45 GHz; 25 mW/cm2 for 60 min) resulted in activation of peritoneal macrophages that were significantly more viricidal to vaccinia virus as compared to sham-exposed or normal (minimum-handling) controls. Macrophages from microwave-exposed hamsters became activated as early as 6 h after exposure and remained activated for up to 12 days. The activation of macrophages by microwave exposure paralleled the macrophage activation after vaccinia virus immunization. Activated macrophages from vaccinia-immunized hamsters did not differ in their viricidal activity when the hamsters were microwave- or sham-exposed. Exposure for 60 min at 15 mW/cm2 did not activate the macrophages while 40 mW/cm2 exposure was harmful to some hamsters. Average maximum core temperatures in the exposed (25 mW/cm2) and sham groups were 40.5 degrees C (+/- 0.35 SD) and 38.4 degrees C (+/- 0.5 SD), respectively. In vitro heating of macrophages to 40.5 degrees C was not as effective as in vivo microwave exposure in activating macrophages to the viricidal state. Macrophages from normal, sham-exposed, and microwave-exposed hamsters were not morphologically different, and they all phagocytosed India ink particles. Moreover, immune macrophage cytotoxicity for virus-infected or noninfected target cells was not suppressed in the microwave-irradiated group (25 mW/cm2, 1 h) as compared to sham-exposed controls, indicating that peritoneal macrophages were not functionally suppressed or injured by microwave hyperthermia.

Animals↗
PubMed1992

Microwave-stimulated glutaraldehyde and osmium tetroxide fixation of plant tissue: ultrastructural preservation in seconds.

Microwave-enhanced fixation of animal tissues for electron microscopy has gained in interest in recent years. Attempts to use microwave irradiation for the preparation of plant tissues are rare. In this study; I report on microwave conditions which allow a high quality preservation of plant cell structure. Tissues used were: internodes of Chara vulgaris, leaves of Hordeum vulgare, root tips of Lepidium sativum. Microwave irradiation was done with a commercial microwave oven (Sharp R-5975). Fixatives used were: 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer, pH 7.2 and 1% osmium tetroxide in veronal/acetate buffer, pH 7.2. Conventional fixations with glutaraldehyde/osmium were compared with microwave fixations. Examinations of thin sections showed that microwave fixation (glutaraldehyde or sequential aldehyde/osmium) is an attractive and rapid alternative method for processing plant tissues for electron microscopy. The optimal conditions found were: microwave oven at power level 50 W, 6.5 ml of fixative solution, irradiation times between 32-34 s, final temperature between 40 degrees C and 47 degrees C.

Chlorophyta↗
PubMedDate not supplied

'Trouble-shooting' microwave accelerated procedures in histology and histochemistry: understanding and dealing with artefacts, errors and hazards.

Heating by microwave irradiation (microwaving) is a controllable way to accelerate most processes of diffusion and many chemical reactions occurring in histoprocessing and histochemistry. Consequently, microwaving can be particularly time-saving. However, apart from desirable accelerations, unwanted diffusions and reactions may also occur. These can generate artefacts such as extraction of tissue components, chemical alterations of cellular content, and decomposition of thermally labile staining reagents. Artefacts may arise at all stages of histoprocessing, from fixation, through embedding, to staining. Whereas all artefacts result from heating, some specifically involve microwave ovens; e.g. irregular heating due to inhomogeneities in the microwave field, and ageing of the magnetron. Microwaving can involve certain hazards. Most of them also arise in conventional ovens, but a few are unique to microwave ovens; for example, aqueous contents heating faster than glass containers, and sparking due to labels written in pencil. The 'trouble-shooting' of microwave procedures requires an understanding of the nature of the heating process and of the procedure in question. In order to achieve this, the development and application of 'trouble-shooting' charts for commonly used procedures is both recommended and illustrated.

Histocytochemistry↗
PubMed1989

Microwave induced stimulation of 32Pi incorporation into phosphoinositides of rat brain synaptosomes.

Exposure of synaptosomes to microwave radiation at a power density of 10 mW/sq cm or more produced stimulation of the 32Pi-incorporation into phosphoinositides. The extent of 32Pi incorporation was found to be much more pronounced in phosphatidylinositol-4-phosphate (PIP), and phosphatidylinositol-4,5-bisphosphate (PIP2) as compared to phosphatidylinositol (PI) and phosphatidic acid (PA). Other lipids were also found to incorporate 32Pi but no significant changes in their labeling were seen after exposure to microwave radiation. Inclusion of 10 mM lithium in the medium reduced the basal labeling of PIP2, PIP and PI and increased PA labeling. Li+ also inhibited the microwave stimulated PIP2, PIP and PI labeling but had no effect on PA labeling. Calcium ionophore, A23187, inhibited the basal and microwave stimulated 32Pi labeling of PIP and PIP2, stimulated basal labeling of PA and PI and had no effect on microwave stimulated PA and PI labeling. Calcium chelator, EGTA, on the other hand, had no effect on basal labeling of PA and PI, stimulated basal PIP and PIP2 labeling but did not alter microwave stimulated labeling of these lipids. Exposure of synaptosomes to microwave radiation did not alter the chemical concentration of phosphoinositides indicating that the turnover of these lipids was altered. These results suggest that low frequency microwave radiation alter the metabolism of inositol phospholipids by enhancing their turnover and thus may affect the transmembrane signalling in the nerve endings.

Animals↗
PubMed2005

Percutaneous microwave and radiofrequency ablation for hepatocellular carcinoma: a retrospective comparative study.

BACKGROUND: Percutaneous microwave ablation and radiofrequency ablation are two commonly used modalities for the treatment of hepatocellular carcinoma; however, comparisons of them have not been documented adequately. METHODS: Of 102 patients with biopsy-proved hepatocellular carcinoma, 49 (98 nodules) were treated percutaneously with microwave ablation and 53 (72 nodules) with radiofrequency ablation. The local tumor control, complications related to treatment, and long-term results of the two modalities were compared retrospectively. RESULTS: The complete ablation rates were 94.9% (93/98) using microwave ablation vs 93.1% (67/72) using radiofrequency ablation (P = 0.75), and no significant differences were found either in the ablation of tumors of 3.0 cm or less (P = 1.00) or in those of more than 3.0 cm (P = 1.00) between the two modalities. The local recurrence rates were 11.8% (11/93) using microwave ablation vs 20.9% (14/67) using radiofrequency ablation (P = 0.12), and there were no significant differences between the two modalities either in tumors of 3.0 cm or less (P = 0.36) or in those of more than 3.0 cm (P = 0.82). The rates of major complications associated with microwave ablation and radiofrequency ablation were 8.2% (4/49) vs 5.7% (3/53; P = 0.71). The disease-free survival rates in the microwave ablation group were 45.9%, 26.9%, 26.9%, and 13.4% at 1, 2, 3, and 4 years, respectively, and those in the radiofrequency ablation group were 37.2%, 20.7%, and 15.5% at 1, 2 and 3 years, respectively (P = 0.53). The 1-, 2-, 3-, and 4-year cumulative survival rates for patients who underwent microwave ablation were 81.6%, 61.2%, 50.5%, and 36.8%, respectively, and for patients who underwent radiofrequency ablation the rates were 71.7%, 47.2%, 37.6%, and 24.2%, respectively (P = 0.12). CONCLUSIONS: Percutaneous microwave ablation and radiofrequency ablation are both effective methods in treating hepatocellular carcinomas. The local tumor control, complications related to treatment, and long-term survivals were equivalent for the two modalities.

Adult↗
PubMed1989

Comparative effect of microwaves and boiling on the denaturation of DNA.

The effect of heat and microwave denaturation of small volumes of double-stranded plasmid DNA has been compared. Samples of intact plasmid DNA had plasmid DNA linearized by digestion with EcoRI were conventionally denatured in a boiling water bath or denatured by 2450 MHz of microwave energy for 0-300 s. Heat denaturation for periods longer than 120 s caused breakdown of linearized plasmid DNA; however, microwave denaturation for 10-300 s caused no apparent degradation of linearized DNA. Breakdown of DNA forms II and III was noted in plasmid DNA subjected to 300 s of either heat or microwave denaturation but breakdown of forms II and III occurred more quickly with heat than with microwave treatment. Microwave treatment was also found to be better than heat to denature 32P-labeled DNA probes subsequently used to detect homologous DNA samples immobilized on nitrocellulose filters. A microwave-treated 32P-labeled DNA probe was able to hybridize to DNA samples 20 times more dilute than a heat-treated 32P-labeled DNA probe. Depending on the form of DNA to be analyzed, these results indicate that small volumes of DNA solutions and radiolabeled DNA probes can be effectively denatured in a conventional microwave oven.

DNA↗
PubMed1994

Microwave technology in diagnostic neuropathology.

The microwave oven has a large range of potential applications in diagnostic neuropathology, ranging from tissue fixation and processing for light and electron microscopy to immunocytochemistry and molecular neuropathology. This review highlights the major current applications for the microwave oven and emphasises areas of particular recent interest. Established microwave techniques are discussed and suggested modifications to published staining techniques are included. Future potential diagnostic applications of microwave technology are emphasised, particularly in terms of in situ hybridisation and immunocytochemistry. Although many microwave techniques for use in diagnostic neuropathology are clearly established, widespread use of the microwave oven has not yet occurred in most neuropathology laboratories. The reasons for this apparent delay and some occasional difficulties in the use of the microwave oven are discussed. Increasing clinical demand for rapid diagnosis (particularly with the use of stereotactic brain biopsy techniques in providing tissue specimens for surgical neuropathology) will enable neuropathologists and laboratory technical staff alike to reconsider the use of the microwave oven for many laboratory techniques and reassess the wide range of potential applications and benefits that this useful tool has to offer.

Animals↗
PubMed1994

Microwave balloon angioplasty effectively seals arterial dissections in an atherosclerotic rabbit model.

OBJECTIVES: The purpose of this study was to determine the effectiveness of microwave balloon angioplasty in sealing arterial dissections and to characterize the histologic features associated with this intervention. BACKGROUND: Coronary dissection accompanying balloon dilation is frequently associated with abrupt closure and acute ischemic complications. Effective management of this complication remains an active area of investigation. Because thermal energy is effective in welding separated atherosclerotic plaques, a microwave-based catheter system that provides controlled local heating was utilized in vessels with angioplasty-induced dissections. METHODS: Iliac artery dissections were induced in ahypercholesterolemic rabbit model. Vessels were randomly assigned to treatment with standard balloon angioplasty (control vessels) or microwave balloon angioplasty using an average temperature of 80 degrees C. The response of the artery was assessed angiographically and histologically. RESULTS: Angiographic success, defined as a reduction of dissection length by > 50% or the resolution of lumen haziness, was achieved in 63% of microwave-treated vessels and in 16% of control vessels (p < 0.005). Dissection length (mean +/- SD) was reduced 8.0 +/- 4.8 mm in microwave-treated vessels compared with 0.1 +/- 7.9 mm in vessels receiving standard balloon inflations (p < 0.005). Cellular necrosis was more commonly observed in microwave-treated vessels than in control vessels (73% vs. 17%, p < 0.05), but less intraluminal thrombus was seen in vessels exposed to microwave energy (p < 0.05). CONCLUSIONS: Microwave balloon angioplasty is more effective than routine balloon inflations in sealing arterial dissections in this model and appears to be less thrombogenic in these markedly disrupted vessels.

Angiography↗
PubMed1994

Microwaves for immunohistochemistry.

Microwaves are now widely used in immunohistochemistry for fixing and stabilizing tissue prior to embedding and cutting, for antigen retrieval and for immunoincubations. These techniques can be used for frozen sections and for material embedded in paraffin and plastic. Material prepared in this way shows high contrast in light microscopy. In principle, these microwave methods can also be used for electron microscopy. To be successful in the application of these techniques, insight into the physics of exposure to microwaves and the effects of microwaves on the material is a must. Microwave immunohistochemistry depends on optimal temperature control. To guarantee this, special measures should be taken and dedicated laboratory ovens should be used. The recently developed Coverplate units facilitate immunoincubations in the microwave oven. We show that the total microwave approach, combining microwave fixation, embedding and immunoincubations, is very useful for confocal microscopy.

Antigens↗
PubMed2005

Salt-assisted acid hydrolysis of chitosan to oligomers under microwave irradiation.

The effect of inorganic salts such as sodium chloride on the hydrolysis of chitosan in a microwave field was investigated. While it is known that microwave heating is a convenient way to obtain a wide range of products of different molecular weights only by changing the reaction time and/or the radiation power, the addition of some inorganic salts was shown to effectively accelerate the degradation of chitosan under microwave irradiation. The molecular weight of the degraded chitosan obtained by microwave irradiation was considerably lower than that obtained by traditional heating. Moreover, the molecular weight of degraded chitosan obtained by microwave irradiation assisted under the conditions of added salt was considerably lower than that obtained by microwave irradiation without added salt. Furthermore, the effect of ionic strength of the added salts was not linked with the change of molecular weight. FTIR spectral analyses demonstrated that a significantly shorter time was required to obtain a satisfactory molecular weight by the microwave irradiation-assisted inorganic salt method than by microwave irradiation without inorganic salts and conventional technology.

Calcium Chloride↗
PubMed2005

Comparison of chromatographic band profiles obtained under microwave irradiated and non-irradiated reversed-phase liquid chromatography column.

The possible influence of the application of microwave energy to a reversed-phase liquid chromatography column on the mass transfer kinetics and the thermodynamics of equilibrium between mobile and stationary phases was examined. Chromatograms of propylbenzene and phenol were recorded under the same experimental conditions, on the same column, successively irradiated and not. The effect of microwave irradiation on the mass transfer kinetics was determined by measuring the second moment of small pulses of propylbenzene in a 70:30 (v/v) solution of methanol in water and microwave outputs of 15 and 30 W. The effect of microwave irradiation on the equilibrium thermodynamics was determined by measuring the elution time of breakthrough curves of phenol at high concentrations in a 20:80 (v/v) solution of methanol and water and microwave outputs of 15, 50, and 150 W. A qualitative comparison of the profiles of the propylbenzene peaks obtained with and without irradiation suggests that this irradiation affects significantly the peak shapes. However, a qualitative comparison of the profiles of the breakthrough curves of phenol obtained with and without irradiation suggests that this irradiation has no significant effect on their shapes. The peak sharpening observed may be due to an increase in the diffusivity, resulting from the dielectric polarization under microwave irradiation. This effect is directly related to an increase of the rate of mass transfers in the column. In contrast, the similarity of the overloaded band profiles at high concentrations suggests that the equilibrium thermodynamics is unaffected by microwave irradiation. This may be explained by the transparence of the stationary phase to microwaves at 2.45 GHz. The column temperature was measured at the column outlet under irradiation powers of 15, 30, 50, and 150 W. It increases with increasing power, the corresponding effluent temperatures being 25+/-1, 30+/-1, 35+/-1, and 45+/-1 degrees C, respectively.

Chromatography, Liquid↗
PubMed2005

Aging and microwave effects on alginate/chitosan matrices.

The influence of microwave irradiation on the drug release properties of freshly prepared and aged alginate, alginate-chitosan and chitosan beads was investigated. The beads were prepared by extrusion method with sulphathiazole as a model drug. The dried beads were subjected to microwave irradiation at 80 W for 10 min, 20 min or three consecutive cycles of 10 and 20 min, respectively. The profiles of drug dissolution, drug content, drug stability, drug polymorphism, drug-polymer interaction, polymer crosslinkage and complexation were determined by dissolution testing, drug content assay, differential scanning calorimetry and Fourier transform infra-red spectroscopy. The chemical stability of drug embedded in beads was unaffected by microwave conditions and length of storage time. The release property of drug was mainly governed by the extent of polymer interaction in beads. The aged alginate beads required intermittent cycles of microwave irradiation to induce drug release retarding effect in contrast to their freshly prepared samples. Unlike the alginate beads, the level of polymer interaction was higher in aged alginate-chitosan beads than the corresponding fresh beads. The drug release retarding property of aged alginate-chitosan beads could be significantly enhanced through subjecting the beads to microwave irradiation for 10 min. No further change in drug release from these beads was observed beyond 30 min of microwave irradiation. Unlike beads containing alginate, the rate and extent of drug released from the aged chitosan beads were higher upon treatment by microwave in spite of the higher degree of polymer interaction shown by the latter on prolonged storage. The observation suggested that the response of polymer matrix to microwave irradiation in induction of drug release retarding property was largely affected by the molecular arrangement of the polymer chains.

Alginates↗