Jeongeun Seo

Natural Sunflower Pollen as a Drug Delivery Vehicle

In nature, pollen grains play a vital role for encapsulation. Many pollen species exist which are often used as human food supplements. Dynamic image particle analysis, scanning electron microscopy, and confocal microscopy analysis confirmed the size, structural uniformity, and macromolecular encapsulation in sunflower pollen, paving the way to explore natural pollen grains for the encapsulation of therapeutic molecules.

Eco-friendly streamlined process for sporopollenin exine capsule extraction.

Sporopollenin exine capsules (SECs) extracted from Lycopodium clavatum spores are an attractive biomaterial possessing a highly robust structure suitable for microencapsulation strategies. Despite several decades of research into SEC extraction methods, the protocols commonly used for L. clavatum still entail processing with both alkaline and acidolysis steps at temperatures up to 180 °C and lasting up to 7 days. Herein, we demonstrate a significantly streamlined processing regimen, which indicates that much lower temperatures and processing durations can be used without alkaline lysis. By employing CHN elemental analysis, scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), and dynamic image particle analysis (DIPA), the optimum conditions for L. clavatum SEC processing were determined to include 30 hours acidolysis at 70 °C without alkaline lysis. Extending these findings to proof-of-concept encapsulation studies, we further demonstrate that our SECs are able to achieve a loading of 0.170 ± 0.01 g BSA per 1 g SECs by vacuum-assisted loading. Taken together, our streamlined processing method and corresponding characterization of SECs provides important insights for the development of applications including drug delivery, cosmetics, personal care products, and foods.

Extraction of sporopollenin exine capsules from sunflower pollen grains

Sporopollenin exine capsules (SECs) are highly robust natural microscale capsules that can be extracted from plant spores and pollen grains, albeit through complex processing schemes. Herein, we report new insights into pollen processing by alkaline lysis and acidolysis with various process conditions. Alkaline lysis of sunflower pollen grains damages the unique pollen microstructure and acidolysis enables us to devise a simple process to extract SECs from sunflower pollen grains with a uniform particle size distribution. The SECs retain the natural morphology, offering an improved general scheme to streamline pollen processing for biomaterial applications.

Plasmonic Nanohole Sensor for Capturing Single Virus‐Like Particles toward Virucidal Drug Evaluation

A plasmonic nanohole sensor for virus-like particle capture and virucidal drug evaluation is reported. Using a materials-selective surface functionalization scheme, passive immobilization of virus-like particles only within the nanoholes is achieved. The findings demonstrate that a low surface coverage of particles only inside the functionalized nanoholes significantly improves nanoplasmonic sensing performance over conventional nanohole arrays.

Biofunctionalized Hydrogel Microscaffolds Promote 3D Hepatic Sheet Morphology.

Development of artificial tissues providing the proper geometrical, mechanical, and environmental cues for cells is highly coveted in the field of tissue engineering. Recently, microfabrication strategies in combination with other chemistries have been utilized to capture the architectural complexity of intricate organs, such as the liver, in in vitro platforms. Here it is shown that a biofunctionalized poly (ethylene glycol) (PEG) hydrogel scaffold, fabricated using a sphere-template, facilitates hepatic sheet formation that follows the microscale patterns of the scaffold surface. The design takes advantage of the excellent diffusion properties of porous, uniform 3D hydrogel platforms, and the enhanced-cell-extracellular matrix interaction with the display of conjugated collagen type I, which in turn elicits favorable Huh-7.5 response. Collectively, the experimental findings and corresponding simulations demonstrate the importance of biofunctionalized porous scaffolds and indicate that the microscaffold shows promise in liver tissue engineering applications and provides distinct advantages over current cell sheet and hepatocyte spheroid technologies.

Membrane attack complex formation on a supported lipid bilayer: initial steps towards a CARPA predictor nanodevice

Abstract The rapid advance of nanomedicines and biologicals in pharmacotherapy gives increasing importance to a common adverse effect of these modern therapeutics: complement (C) activation-related pseudoallergy (CARPA). CARPA is a relatively frequent and potentially lethal acute immune toxicity of many intravenous drugs that contain nanoparticles or proteins, whose prediction by laboratory or in vivo testing has not yet been solved. Preliminary studies suggest that proneness of the drug to cause C activation in the blood of patients may predict the individual risk of CARPA, thus, a sensitive and rapid bedside assay for individualized assessment of a drug’s C activating potential could alleviate the CARPA problem. The goal of the present study was to lay down the foundations of a novel approach for real-time sensing of C activation on a supported lipid bilayer platform. We utilized the quartz crystal microbalance with dissipation (QCM-D) monitoring technique to measure the self-assembly of C terminal complex (or membrane attack complex [MAC]) on supported lipid bilayers rapidly assembled by the solvent-assisted lipid bilayer (SALB) formation method, as an immediate measure of C activation. By measuring the changes in frequency and energy dissipation of deposited protein, the technique allows extremely sensitive real-time quantification of the sequential assembly of MAC from its molecular components (C5b-6, C7, C8 and C9) and hence, measure C activation in the ambient medium. The present paper delineates the technique and our initial evidence with purified C proteins that the approach enables sensitive and rapid (real-time) quantification of MAC formation on a silicon-supported planar (phospho) lipid bilayer, which can be used as an endpoint in a clinically useful bedside C activation assay.

Inflated Sporopollenin Exine Capsules Obtained from Thin-Walled Pollen

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.