Role of Sporopollenin Shell Interfacial Properties in Protein Adsorption

Harnessing Electrostatic Forces: A Review of Bees as Bioindicators for Particulate Matter Detection

Bees (Hymenoptera, Anthophila) are widely recognized for their essential ecological roles, including pollination and biodiversity maintenance. Recently, their ability to collect environmental particulate matter through electrostatic forces has been explored for biomonitoring purposes. This review integrates knowledge on electrostatic pollen adhesion with emerging insights into particulate matter adhesion to bees, emphasizing their potential as bioindicators. The mechanisms of electrostatic adhesion, influenced by factors such as the physicochemical properties of particulate matter and bee morphology, are discussed in detail. Additionally, the study evaluates the adhesion efficiency of pollutants, including heavy metals, microplastics, nanoplastics, pathogens, pesticides, radionuclides, and volatile organic compounds. This multidisciplinary approach underscores the role of bees in advancing environmental monitoring methodologies and offers innovative tools for assessing ecosystem health while addressing the drivers of bee decline.

First Cu-nanostar as a sustainable catalyst realized through synergistic effects of bowl-shaped features and surface activation of sporopollenin exine

Recently, nanostar-shaped structures, including gold nanostars (NS), have drawn much attention for their potential use in surface-enhanced Raman spectroscopy (SERS) and catalysis. Yet, very few studies have been conducted on Cu-Au hybrid NS, and there are none for Cu-based NS. Herein, we describe an effective method for controlling copper-oxide nanostar (ESP-PEI-CuI/IIO-NS) growth using sporopollenin as a sustainable template material. However, ESP-PEI-CuI/IIO-NS growth depends on sporopollenin surface functionalization. Sporopollenin surface activation was done by amine functionalization with polyethyleneimine (PEI), without which ESP-PEI-CuI/IIO-NS growth was not observed. The sporopollenin's exine (outer wall) has a bowl-like structure, which mediates the growth of Cu nanorods, resulting in an NS morphology. Furthermore, due to their increased surface area, ESP-PEI-CuI/IIO-NS showed excellent catalytic activity for Huisgen 1,3-dipolar cycloadditions even when used in H2O and without additives under green conditions. This approach utilising biomass as a sustainable template would pave the way for developing controlled growth of nanostructures for SERS-related and catalytic applications.

A label-free colorimetric biosensor utilizing natural material for highly sensitive exosome detection

Exosomes, extracellular vesicles secreted by cells, play a crucial role in intercellular communication by transferring information from source cells to recipient cells. These vesicles carry important biomarkers, including nucleic acids and proteins, which provide valuable insights into the parent cells' status. As a result, exosomes have emerged as noninvasive indicators for the early diagnosis of cancer. Colorimetric biosensors have garnered significant attention due to their cost-effectiveness, simplicity, rapid response, and reproducibility. In this study, we employ sporopollenin microcapsules (SP), a natural biopolymer material derived from pollen, as a substrate for gold nanoparticles (AuNPs). By modifying the SP-Au complex with CD63 aptamers, we develop a label-free colorimetric biosensor for exosome detection. In the absence of exosomes, the SP-Au complex catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), resulting in a color change from colorless to blue. However, the addition of exosomes inhibits the catalytic activity of the SP-Au complex due to coverage of exosomes on AuNPs. This colorimetric biosensor exhibits high sensitivity and selectivity for exosome detection, with a detection limit of 10 particles/μL and a wide linear range of 10 - 108 particles/μL. Additionally, the SP-Au biosensor demonstrates remarkable resistance to serum protein adsorption and excellent catalytic stability even in harsh environments, making it highly suitable for clinical diagnostics.

A natural biomaterial promotes hybridization chain reaction for ultra-sensitive detection of miRNA-155

MicroRNA (miRNA) is an important biomarker for early diagnosis of cancers. However, sensitive and convenient methods for miRNA detection remain a challenge. Here, we use a natural biopolymer sporopollenin purified from Ganoderma lucidum spores as a substrate for isothermal amplification (hybridization chain reaction, HCR). Sporopollenin capsules (SP) promotes HCR and forms longer and more abundant double-stranded DNA (dsDNA) than graphene oxide (GO) and carbon nanotubes (CNTs). The nanoporous structure of sporopollenin capsules containing abundant water provides a hydrous environment and enhances the hybridization efficiency of DNA significantly. We construct an ultrasensitive fluorescent biosensor to detect miR-155. The efficient HCR amplification on SP leads to an ultralow detection limit of 1 aM for miR-155 and a wide linear range of 1 aM-10 fM (R2 = 0.99). Furthermore, our fluorescence biosensor can discriminate miRNA mutants with high selectivity. This biosensor is also highly sensitive in human serum (detection limit 10 aM). It adsorbs less serum protein than GO and CNTs, thus minimizing the interference caused by the non-specific adsorption. Our study would promote medical application of SP-based biosensor in the future.

Multifaceted roles of pollen in the management of cancer

Oral drug delivery of microparticles demonstrates shortcomings like aggregation, decreased loading capacity and batch-to-batch variation, which limits its scale-up. Later, porous structures gained attention because of their large surface-to-volume ratio, high loading capacity and ability to carry biomacromolecules, which undergo degradation in GIT. But there are pitfalls like non-uniform particle size distribution, the impact of porogen properties, and harsh chemicals. To circumvent these drawbacks, natural carriers like pollen are explored in drug delivery, which withstands harsh environments. This property helps to subdue the acid-sensitive drug in GIT. It shows uniform particle size distribution within the species. On the other side, they contain phytoconstituents like flavonoids and polysaccharides, which possess various pharmacological applications. Therefore, pollen has the capability as a carrier system and therapeutic agent. This review focuses on pollen's microstructure, composition and utility in cancer management. The extraction strategies, characterisation techniques and chemical structure of sporopollenin exine capsule, its use in the oral delivery of antineoplastic drugs, and emerging cancer treatments like photothermal therapy, immunotherapy and microrobots have been highlighted. We have mentioned a note on the anticancer activity of pollen extract. Further, we have summarised the regulatory perspective, bottlenecks and way forward associated with pollen.

Ultrasound-Responsive Oxygen-Carrying Pollen for Enhancing Chemo-Sonodynamic Therapy of Breast Cancer

The tumor-suppressing efficacy of either chemotherapeutics or gaseous drugs has been confirmed in treating the triple negative breast cancer (TNBC), while the efficacy of single treatment is usually dissatisfactory. Herein, a novel ultrasound responsive natural pollen delivery system is presented to simultaneously load chemotherapeutics and gaseous drugs for synergistic treatment of TNBC. The hollow structure of pollen grains carries oxygen-enriched perfluorocarbon (PFC), and the porous spinous process structure adsorbs the chemotherapeutic drug doxorubicin (DOX) (PO/D-PGs). Ultrasound can trigger the oxygen release from PFC and excite DOX, which is not only a chemotherapeutic but also a sonosensitizer, to realize chemo-sonodynamic therapy. The PO/D-PGs are demonstrated to effectively enhance oxygen concentration and increase the production of reactive oxygen species in the presence of low-intensity ultrasound, synergistically enhancing the tumor killing ability. Thus, the synergistic therapy based on ultrasound-facilitated PO/D-PGs significantly enhances the antitumor effect in the mouse TNBC model. It is believed that the proposed natural pollen cross-state microcarrier can be used as an effective strategy to enhance chemo-sonodynamic therapy for TNBC.

Lysozyme is Sterically Trapped Within the Silica Cage in Bioinspired Silica-Lysozyme Composites: A Multi-Technique Understanding of Elusive Protein-Material Interactions

Lysozyme is widely known to promote the formation of condensed silica networks from solutions containing silicic acid, in a reproducible and cost-effective way. However, little is known about the fate of the protein after the formation of the silica particles. Also, the relative arrangement of the different components in the resulting material is a matter of debate. In this study, we investigate the nature of the protein-silica interactions by means of solid-state nuclear magnetic resonance spectroscopy, small-angle X-ray scattering, and electron microscopy. We find that lysozyme and silica are in intimate contact and strongly interacting, but their interaction is neither covalent nor electrostatic: lysozyme is mostly trapped inside the silica by steric effects.