Capsule Destruction Research Articles

Engineered multivalent DNA capsules for multiplexed detection of genotoxicants via versatile controlled release mechanisms

Assessing the risks associated with genotoxic compounds is challenging because of their complex genotoxicity and the difficulty in the dynamic monitoring of coexisting hazards. In this paper, DNA-assembly-based multistimulus responsive capsules that can detect multiple genotoxic agents simultaneously are presented. By exploiting the sequence- and reactivity-editable properties of DNA, DNA sequences in a DNA shell are designed to exhibit multivalent susceptibility against ultraviolet B radiation, aflatoxin B1, and styrene oxide. Upon exposure to genotoxicants, the developed DNA capsules dissociate because of the production of DNA adducts or aptamer–ligand complex-activated dehybridization, which results in the release of encapsulated fluorophores for a measure of the genotoxicant level. The fluorophore release kinetics for each genotoxicant is investigated. Moreover, the destruction behaviors of the developed capsules are evaluated in binary and ternary toxin mixtures. Multiple linear regression indicates the existence of a strong relationship between the fluorescent response and the genotoxicant level; the result highlights the significance of particular genotoxicant and the antagonistic effect of interacting genotoxic substances on capsule destruction. This DNA architecture allows the monitoring of human exposure to genotoxic agents, which enables the timely adoption of remedial measures, and benefits development of an endogenous genotoxin-responsive drug delivery system.

Destruction of polyelectrolyte microcapsules and release of FITC-dextran from them by the influence of sodium dodecyl sulfonate

Polyelectrolyte microcapsules can be applied as microcontainers for the delivery of a wide range of substances, and it is important to search for new methods for capsule destruction and releasing substances from them. In this work, we studied the possibility of using sodium dodecyl sulfonate (SDS) for the release of fluorescein isothiocyanate—dextran from six-layer microcapsules composed of PAH and PSS. It was shown that the presence of SDS in the medium, at a concentration of 3000 μg/ml, leads to the destruction of polyelectrolyte microcapsules and the release of the substance from them (54% of the amount of the encapsulated substance), while the main part of the FITC-dextran released during the first hours of incubation. At an SDS concentration of 100 μg/ml, the substance released is uniform and is 44% in 24 h. At SDS concentrations from 50 to 100 μg/ml, the process of destruction of microcapsules proceeds more slowly. At SDS concentrations from 10 to 50 μg/ml, microcapsules are not degraded.

The effectiveness of plant hydrocolloids at maintaining the quality characteristics of the encapsulated form of L-phenylalanine-ammonia-lyase

The effect of three types of polysaccharides (agar-agar, carrageenan, hydroxypropyl methylcellulose) on the activity and stability during storage at given temperature conditions of the enzyme preparation L-phenylalanine ammonia-lyase was studied. It was found that the most suitable storage temperature for encapsulated L-phenylalanine-ammonia-lyase is room temperature up to 25 °C for all samples of capsules from plant polysaccharides. Samples of capsules with agar-agar and hydroxypropyl methylcellulose under different temperature conditions inhibited the decrease in enzyme activity, which in other samples of capsules reached 90% in 6 months of storage. In samples of capsules with carrageenan at temperatures of 4 °C and 30 °C, there was a significant decrease in the activity of the enzyme preparation. Selection of capsule samples from plant polysaccharides suitable for L-phenylalanine-ammonia-lyase replacement therapy is done after studying the mechanisms of capsule destruction under conditions close to the conditions of the gastrointestinal tract, to which the next stage of our research will be devoted.

Gastrointestinal stromal tumor of the esophagus: current issues of diagnosis, surgery and drug therapy.

Gastrointestinal stromal tumors (GISTs) often arise in the stomach and small intestine, while esophageal GISTs are rare. Due to their rarity, clinicopathological data on esophageal GISTs are extremely limited, and this results in a lack of clear recommendations concerning optimal surgical management for esophageal GISTs. It is difficult to distinguish esophageal GIST from leiomyoma, the most frequent esophageal mesenchymal tumor, prior to resection, because the two types of tumors appear similar on computed tomography (CT), endoscopic ultrasound (EUS), and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). Fine-needle aspiration biopsy (FNAB) under EUS enables definitive diagnosis, but it is often avoided because scarring could make enucleation more difficult and increase the risk of tumor dissemination by capsule destruction. Esophageal segmental and wedge resections are not usually performed due to the anatomical peculiarity of the esophagus, and the surgical options are limited to the highly invasive esophagectomy or the much less invasive surgical tumor enucleation. The decision as to which surgical procedure should be performed for esophageal GISTs is still under debate. Tumor enucleation may be permitted for smaller tumors, and esophagectomy may be recommended for larger GISTs or high-risk tumors with a high mitotic rate. The purpose of neoadjuvant imatinib administration is downsizing of the GIST to reduce the extent of resection and to reduce the risk of intraoperative complications, including tumor rupture. The efficacy of neoadjuvant/adjuvant imatinib therapy for esophageal GISTs is poorly understood, because the reports are limited to case reports or case series with small numbers. More clinicopathological data and clinical trials for esophageal GIST are expected.

Fabrication of polylactic acid (PLA) microcapsules and release of the internal hydrophilic substance under ultrasound irradiation

Hollow microcapsules have been considered for potential application as drug or gene carriers. Targeted drug or gene release to tumor vascular can be achieved by destroying the capsules by high-intensity ultrasound. This report investigates fabrication of microcapsules having biocompatible polylactic acid (PLA) shell and the mechanical property for the destruction under ultrasound irradiation. The PLA hollow microcapsules with the diameter of 1 to 35 μm were fabricated by double emulsion method. Red fluorescent dye which is substitute for drug was enclosed into the capsules. The capsules have trilaminar structure. Inner air is surrounded by red fluorescent, and the PLA shell encloses them. Shell thickness of capsules was distributed from 100 nm to 3 μm. Destruction of the fabricated capsules was investigated by using ultrasound pulse with the center frequencies from 500 kHz to 2 MHz. The behavior of capsule was observed by using an optical microscope under ultrasound irradiation. The frequency dependence of the capsule destruction was investigated and 35% of the capsules with the resonance size was destroyed with 400 kPa at 700 kHz. The capsule shell was ruptured by the ultrasound, and then the inner dye was released; the dye was completely released for 120 seconds under ultrasound irradiation.

Relationship Between Computed Tomography Manifestations of Thymic Epithelial Tumors and the WHO Pathological Classification

To explore the relationship between computed tomography (CT) manifestations of thymoma and its WHO pathological classification. One hundred and five histopathologically confirmed cases were collected for their pathological and CT characteristics and results were statistically compared between different pathological types of thymoma. Tumor size, shape, necrosis or cystic change, capsule integrity, invasion to the adjacent tissue, lymphadenopathy, and the presence of pleural effusion were significantly different between different pathological types of thymomas (P<0.05). Type B2, B3 tumors and thymic carcinomas were greater in size than other types. More than 50% of type B3 tumors and thymic carcinomas had a tumor size greater than 10 cm. The shape of types A, AB, and B1 tumors were mostly round or oval, whereas 75% of type B3 tumors and 85% of thymic carcinomas were irregular in shape. Necrosis or cystic change occurred in 67% of type B3 thymomas and 57% of thymic carcinomas, respectively. The respective figures for capsule destruction were 83% and 100%. Increases in the degree of malignancy were associated with increases in the incidence of surrounding tissue invasion: 33%, 75%, and 81% in type B2, type B3, and thymic carcinomas, respectively. Pleural effusion occurred in 48% of thymic carcinomas, while calcification was observed mostly in type B thymomas. Different pathological types of thymic epithelial tumors have different CT manifestations. Distinctive CT features of thymomas may reflect their pathological types.

Destruction of the gas‐filled capsule using effects of the collapsing bubble near the capsule

A new technique to destroy the gas‐filled capsule is proposed, making use of the collapsing bubble near the capsule in the ultrasound field. At the moment of collapses under the ultrasound irradiation, the bubble causes flow and acoustic wave radiation. These phenomena are expected to assist the destruction of the capsule. We observed the effect of the bubble on this destruction, using a high‐speed video camera which enables the real‐time imaging. In this experiment, we use gas‐filled capsule made of polyvinyl chloride. When no bubble was near the capsule at sound pressure of 60kPa, the capsule showed no vibration. However, in the presence of neighboring bubble, the capsule showed the destruction behavior of the deformation and the emission of internal gas. At higher sound pressure such as over 100kPa, the capsule showed above destruction behavior even if the bubble was not located near the capsule. In the presence of the bubble, however, the capsule was destructed in a shorter time. These experimental results give significant knowledge to a technique manipulating the gas‐filled capsule destruction in the drug delivery system.

New Method for Fabrication of Loaded Micro- and Nanocontainers: Emulsion Encapsulation by Polyelectrolyte Layer-by-Layer Deposition on the Liquid Core

A novel approach to the emulsion encapsulation was developed by combining the advantages of direct encapsulation of a liquid colloidal core with the accuracy and multifunctionality of layer-by-layer polyelectrolyte deposition. Experimental data obtained for the model oil-in-water emulsion confirm unambiguously the alternating PE assembly in the capsule shell as well as the maintenance of the liquid colloidal core. Two different mechanisms of capsule destruction upon interaction with the solid substrate were observed and qualitatively explained. The proposed method can be easily generalized to the preparation of oil-filled capsules in various oil/water/polyelectrolyte systems important in the field of pharmacy, medicine, and food industry.

Acoustic destruction of a microcapsule having a hard plastic shell

Acoustic destruction of a microcapsule having a hard plastic shell is discussed. In an ultrasonic drug delivery system, microcapsules having thin elastic shells release drugs that are contained therein when the shell is destroyed. In this paper, two subjects related to capsule destruction are discussed: the driving pulse duration for capsule destruction and the frequency dependence of capsule destruction. Optical observation of microcapsule destruction is performed with a high-speed video camera. In the case of capsule destruction by a pulse wave, the internal gas of the microcapsule cannot be ejected completely, and a portion of the internal gas remains inside the broken shell. It is found that capsule destruction by pulse waves depends on both the amplitude of the driving pressure and the pulse duration. The frequency dependence of microcapsule destruction also is investigated. In the case of capsule destruction by a low-amplitude acoustic wave, the destruction rate under the resonance condition is higher than under nonresonance conditions. By controlling the driving frequency, selective capsule destruction can be achieved.

Optical Observation of Microcapsule Destruction in an Acoustic Standing Wave

The destruction of microcapsules having an elastic thin shell is discussed. An optical observation of the capsule destruction using a high-speed video camera is carried out. As the driving pressure is increased, the microcapsules trapped at the antinode of an acoustic standing wave show circling movements, and then the microcapsules eventually collapse. At the moment of destruction, it is found that the microcapsules change in shape and the internal gas jets out of the capsule rapidly. The sound pressure threshold for the capsule destruction is the lowest under the resonant condition. The capsule destruction also depends on the existence of free bubbles in the surrounding media. It is found that the mechanism of capsule destruction can be categorized into two types: one is due to the increasing driving sound pressure and the other is due to the existence of the free bubbles in the surrounding media. It is considered that the destructions of multicapsules depend on some parameters; however, these two types of capsule destruction are dominant factors.