Purification of Hollow Sporopollenin Microcapsules from Sunflower and Chamomile Pollen Grains.
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ABSTRACT:
SUBMITTER: Ageitos JM
PROVIDER: S-EPMC8271440 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Sporoderms, the outer layers of plant spores and pollen grains, are some of the most robust biomaterials in nature. In order to evaluate the potential of sporoderms in biomedical applications, we studied the biodegradation in simulated gastrointestinal fluid of sporoderm microcapsules (SDMCs) derived from four different plant species: lycopodium (Lycopodium clavatum L.), camellia (Camellia sinensis L.), cattail (Typha angustifolia L.), and dandelion (Taraxacum officinale L.). Dynamic image particle analysis (DIPA) and field-emission scanning electron microscopy (FE-SEM) were used to investigate the morphological characteristics of the capsules, and Fourier-transform infrared (FTIR) spectroscopy was used to evaluate their chemical properties. We found that SDMCs undergo bulk degradation in a species-dependent manner, with camellia SDMCs undergoing the most extensive degradation, and dandelion and lycopodium SDMCs being the most robust.
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Project description:Sporopollenin is a physically robust and chemically resilient biopolymer that comprises the outermost layer of pollen walls and is the first line of defense against harsh environmental conditions. The unique physicochemical properties of sporopollenin increasingly motivate the extraction of sporopollenin exine capsules (SECs) from pollen walls as a renewable source of organic microcapsules for encapsulation applications. Despite the wide range of different pollen species with varying sizes and wall thicknesses, faithful extraction of pollen-mimetic SECs has been limited to thick-walled pollen capsules with rigid mechanical properties. There is an unmet need to develop methods for producing SECs from thin-walled pollen capsules which constitute a large fraction of all pollen species and have attractive materials properties such as greater aerosol dispersion. Herein, we report the first successful extraction of inflated SEC microcapsules from a thin-walled pollen species (Zea mays), thereby overcoming traditional challenges with mechanical stability and loss of microstructure. Morphological and compositional characterization of the SECs obtained by the newly developed extraction protocol confirms successful protein removal along with preservation of nanoscale architectural features. Looking forward, there is excellent potential to apply similar strategies across a wide range of unexplored thin-walled pollen species.
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Project description:We present facile methods to obtain purified sporopollenin exine capsules, and provide mass balances for classical and novel purification procedures. An ionic liquid, tetrabutyl phosphonium hydroxide turned out to be the most effective in removing the intine wall. The sporopollenin capsules were investigated by fluorescent microscopy, AFM, solid-state NMR and infrared Raman spectroscopy. The latter two methods showed that sunflower and rape exines have different proportions of O-aliphatic and aromatic constituents. Purified exine capsules were coated with functionalized fluorophores. The procedures presented in this paper could contribute to further spread of the applications of this hollow, and chemically highly resistant material.
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Project description:Smart drug delivery systems (SDDSs) are a paradigm shift in drug delivery, particularly in microencapsulation technology where the drug is released in response to an internal and/or external stimulus. In this study, a smart microencapsulation platform was developed using three different types of stimuli triggered release of a model active (rhodamine 6G) from sporopollenin from Lycopodium clavatum. Triggers were based on pH-, thermal- and near infrared light-sensitive polymer composition. Carbopol nanogel and methylcellulose were used as responsive aqueous polymers for pH and thermally triggered release, respectively. Methylcellulose loaded with active and gold nanoparticles was used for photothermal triggered release. The formulations were encapsulated into the empty cores of sporopollenin microcapsules using the compressed tablet technique. The pH triggered release of the active was achieved above pH 7, which was mediated by the swelling of the carbopol nanogel that forced its way out of the elastic trilite scars of the sporopollenin. Results from measuring the active fluorescent intensity and its content over time confirmed the crucial role of carbopol in the pH triggered release. For the thermo-sensitive polymer methylcellulose, it was found that the release of the active from methylcellulose loaded sporopollenin was triggered upon heating the system reaching 90% whereas it levelled out at 40% for methylcellulose-free sporopollenin. The maximum amount of active was released at around 55 °C, where the sol-gel transition of the methylcellulose starts. Photothermally triggered release using near infrared (NIR) laser revealed that the amount of active released from sporopollenin loaded with both gold nanoparticles and methylcellulose was approximately four times higher than that from sporopollenin loaded with methylcellulose/active only, confirming the key role of gold nanoparticles in the release via photothermal heating of the polymer formulation.
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