Light‐Induced Surface Modification of Natural Plant Microparticles: Toward Colloidal Science and Cellular Adhesion Applications

Abstract

Playing an instrumental role in the life of plants, pollen microparticles are one of the most fascinating biological materials in existence, with abundant and renewable supply, ultrahigh durability, and unique, species-specific architectural features. Aside from their biological role, pollen microparticles also demonstrate broad utility as functional materials for drug delivery and microencapsulation, and increasingly for emulsion-type applications. As natural pollen microparticles are predominantly hydrophobic, developing robust surface functionalization strategies to increase surface hydrophilicity would increase the range of colloidal science applications, including opening the door to interfacing microparticles with biological cells. This research investigates the extraction and light-induced surface modification of discrete pollen microparticles from bee-collected pollen granules toward achieving functional control over the responses elicited from discrete particles in colloidal science and cellular applications. Ultravioletozone treatment is shown to increase the proportion of surface elemental oxygen and ketones, leading to increased surface hydrophilicity, enhanced particle dispersibility, tunable control over Pickering emulsion characteristics, and enhanced cellular adhesion. In summary, the findings demonstrate that light-induced surface modification improves the functional properties of pollen microparticles, and such insights also have broad implications across materials science and environmental science applications.

Natural and Eco-Friendly Materials for Triboelectric Energy Harvesting

“…TENGs based on natural materials have been recently investigated in detail, and the conclusions showed that their complex surface architecture causes major impacts on the produced charge, current, or voltage [48][49][50][51]. Since natural materials have hierarchically structured surfaces, surface modification is not required in many cases, and they can be used for polymer modification by soft lithography as well [52][53][54]. Besides, the combination of natural materials with biocompatible polymers allows the production of eco-friendly triboelectric pairs for energy harvesting.…”

Surface modification of plant-based microparticles for colloidal science and cellular adhesion applications

“…important to note that upon more detailed analysis of the narrow scan XPS data, the increase in COR binding can be attributed to ether (COC) binding rather than COH binding ( Table 5.1). attributed to UV-O induced aromatic ring opening [25]. Importantly, the oxidative degradation of the aromatic compound p-coumaric acid has been shown to produce ketone (R2C=O) moieties [24], and p-coumaric acid is known to be one of the major constituents of sporopollenin [22].…”

“…The earliest chemical structure for sporopollenin was proposed in the 1930s that terpenoids which is a class of naturally occurring that is similar to terpenes that are produced by plants to ward off herbivores [18]. And in the 1960s sporopollenin was proposed to be composed of carotenoids or are lipidic in as the cinnamic acids, p-coumaric acid and ferulic acid [21][22][23][24][25][26][27]. These studies were mostly done with sporopollenin extracted from lycopodium, pine and cattail.…”

“…Although S-SMCs are considered a biocompatible material [17,18], there exists very limited information regarding their potential for particle/cell interactions [35,36], and it is unclear how cells may interact with either acid-extracted S-SMCs or UV-O surface modified S-SMCs. Some evidence of cell adhesion to defatted natural pollen particles has been reported, with UV-O surface modification enhancing pollen/cell binding [25]. Extending these capabilities to the more versatile hollow core/shell microparticle structure of S-SMCs might further enable a range of particle/cell systems with broad application possibilities [37][38][39][40].…”

“…Pollen exhibit numerous desirable properties for functional emulsion applications, such as particle monodispersity [13], physicochemical robustness [14], amphiphilicity [15], biocompatibility [16], and complex surface chemistry for potential functionalization and compound binding [17][18][19][20]. In general, there is growing interest in utilizing pollen for a wide range of applications, such as the extraction of pollen shells for microencapsulation and drug-delivery applications [21][22][23][24][25][26][27][28]. Although, sporoderm microcapsules (S-SMCs) have been shown to offer a wide range of potential benefits, they typically rely on harsh chemical extraction protocols, and are limited by requiring additional regulatory approval for use in oral delivery applications.…”