China
Africa
Explore chapters and articles related to this topic
Fluorescence in Phytopreparations
Published in Victoria Vladimirovna Roshchina, Fluorescence of Living Plant Cells for Phytomedicine Preparations, 2020
Victoria Vladimirovna Roshchina
When pollen grains are mature, they often have no maxima in the red region of the fluorescence spectra, whereas in immature pollen grains of catch weed, a maximum at 680 nm, specific to chlorophyll, is observed. The fluorescence of dry immature and mature pollen differs. For instance, immature pollen of Tussilago farfara demonstrated green fluorescence with maxima at 465, 518, and 680 nm in the fluorescence spectra, whereas mature pollen, which lacks chlorophyll, showed mainly yellow fluorescence with maxima at 465, 520, and 535–540 nm (Roshchina et al. 1997a, 1998a). Blue fluorescence (maxima at 465–470 nm and a small shoulder at 665 nm) of immature pollen of Philadelphus grandiflorus changed to yellow-orange emission (maxima at 465, 510–520, and 620 nm) in mature pollen grains (Roshchina et al. 1997a, 1998a). Maxima in mature pollen occur due to the synthesis of carotenoids (maximum 520 nm) and azulenes (maximum 620–640 nm) during the development of the generative microspores (Roshchina et al. 1995, 1997a, 1998a). Luminescent and laser-scanning confocal microscopy have the potential to distinguish mature (without chlorophyll) and immature pollen fluorescing in red due to the chlorophyll. The fluorescence spectra of mature and immature pollen grains of greenhouse and outdoor plants have been shown in an earlier paper (Roshchina et al. 1998a). These differ in intensity of light emission and in the position of maxima of the fluorescence spectra. Mature pollen grains often have no 680 nm maximum, whereas in immature pollen grains of Hymenocallis, a 680 nm maximum, typical of chlorophyll, was observed. Pollen mainly demonstrates clearly seen maxima in the blue-green region (480–500 nm). Sometimes, a third maximum in the orange (550–570 nm) or red region (600–650 nm) appears, as for Matricaria chamomilla, for example. There are one to three maxima (at 460–490, 510–550, and 620–680 nm) in the pollen fluorescence spectra of various species. It depends on the substances contained in the sporopollenin or/and exuded onto the pollen surface. For instance, p-coumaric acid, a monomer in the sporopollenin skeleton, as in pollen of Pinus mugo Turra (Wehling et al. 1989), may emit in blue. Thus, the color of fluorescence, the fluorescence spectra, and the intensity of emission at the maxima may be useful for the analysis of mature and immature pollen or the readiness of pollen to germinate.
Graphene-based materials do not impair physiology, gene expression and growth dynamics of the aeroterrestrial microalga Trebouxia gelatinosa
Published in Nanotoxicology, 2019
Elisa Banchi, Fabio Candotto Carniel, Alice Montagner, Susanna Bosi, Mattia Bramini, Matteo Crosera, Verónica León, Cristina Martín, Alberto Pallavicini, Ester Vázquez, Maurizio Prato, Mauro Tretiach
Studies by Hu et al. (2014) and Ouyang et al. (2015) reported GBM internalization into the aquatic microalgae Chlorella pyrenoidosa and C. vulgaris. These species differ from T. gelatinosa in the thickness and composition of the cell wall, which varies from ∼ 900 nm in the latter (Archibald 1975 and our direct measurements) to only ∼ 20 nm in Chlorella species (Northcote et al. 1958; Yamamoto et al. 2004), where it represents a weaker barrier to GBM internalization. The cell wall of T. gelatinosa consists of five layers of different composition, ranging from highly packed cellulosic fibrils, to a web of polysaccharides and sporopollenin (König and Peveling 1984). Moreover, T. gelatinosa develops a sticky, gelatinous sheath 1.5–2 μm thick outside the cell wall (Archibald 1975; Casano et al. 2015) that forms an adhesive surface (see Figure 4(f)) for the oxygen-rich functional groups spread over the graphene lattice of GO (Amirov et al. 2017), thus preventing its internalization.
Microencapsulation: a pragmatic approach towards delivery of probiotics in gut
Published in Journal of Microencapsulation, 2021
Rabia Iqbal, Atif Liaqat, Muhammad Farhan Jahangir Chughtai, Saira Tanweer, Saima Tehseen, Samreen Ahsan, Muhammad Nadeem, Tariq Mehmood, Syed Junaid Ur Rehman, Kanza Saeed, Nimra Sameed, Shoaib Aziz, Assam Bin Tahir, Adnan Khaliq
In support of these techniques Davis (2014) conducted a study to investigate the viability of Prop. agglomerans E325 using ethidium bromide and SYTO-green under fluorescence microscope. The dead cells were stained red while the viable cells appeared green based on the degree of permeation of the different dyes into non-living and living cells. The noticeable difference with the application of the sporopollenin exine capsules (SECs) as a means of encapsulation is that the SECs may act as a bioreactor and provide time for the encapsulated cells to multiply thousands of times before being released, following the SEC’s burst. The unique advantages of SECs alongside the proposed encapsulation method, demonstrates the potential application of SECs as delivery system of probiotics to the distal part of the human GI tract. Microbeads with greater retention of 6-carboxyfluorescein dye indicated higher cell viability which was described as better retention of water-soluble nutrients within the probiotic cells (Zhao et al.2012). Samedi and Charles (2019) conducted a research to check the functionality of the micro-encapsulated L. reuteriDPC16 cells in comparison to free cells during their transit through a simulated GI tract. For this purpose, an alginate-skim milk-based encapsulation system was used to allow the cells to be released in the simulated intestinal (SI) pH (colonic pH). The probiotic cells displayed no decrease in their functionality, including their ability to adhere to epithelial cells, ability to inhibit the adhesion of E. coli to epithelial cells and growth kinetics. The results demonstrated that microencapsulated cells have greater potential to protect the viability of probiotic cells.
Albumin-based cancer therapeutics for intraperitoneal drug delivery: a review
Published in Drug Delivery, 2020
Leen Van de Sande, Sarah Cosyns, Wouter Willaert, Wim Ceelen
Albumin NPs can be decorated with a variety of targeting ligands to give additional specificity to cancer cell-associated receptors. For instance, anti-cancer drugs were loaded into mannosylated bovine serum albumin (BSA) NPs to target drug-resistant colon cancer cells and tumor-associated macrophages, which both highly express mannose receptors and SPARC (Zhao et al., 2017). Likewise, folate-decorated BSA NPs were developed for the targeted delivery of PTX to exploit overexpression of the folate receptor by a wide range of tumor cell types (Zhao et al., 2010). The glycyrrhetinic acid (GA) receptor is overexpressed in liver cancer cells. Consequently, GA modified rHSA NPs were developed to target liver tumor cells. Qi et al. encapsulated GA-rHSA NPs with DOX (GA-rHSA-DOX) and demonstrated increased cytotoxic activity in liver tumor cells compared to non-targeted NPs (rHSA-DOX) (Qi et al., 2015). Albumin NPs can also be decorated with antibodies such as DI17E6, a monoclonal antibody directed against αv integrins, which are cell membrane-spanning matrix adhesion domains that are highly expressed in various cancer lines. Covalent coupling of DI17E6 onto DOX loaded albumin NPs showed inhibited growth and angiogenesis in melanoma (Wagner et al., 2010). Yu et al. (2016) described albumin NPs decorated with cyclic arginine-glycine-aspartic (cRGD) peptides loaded with gemcitabine for the treatment of pancreatic cancer. The αvβ3 integrins specifically recognize the cRGD motif which suggests the possibility of using cRGD-conjugated carriers to deliver drugs into cancer cells as active tumor targeting therapy. Finally, a sporopollenin-HSA (Sp-HSA) microparticle was developed as a drug carrier. The Sp-HSA particles were loaded successfully with DOX for targeted cancer treatment (Maltas et al., 2016). To date, anti-cancer efficacy studies for these Sp-HSA particles are lacking.