Search

Plant volatile organic compounds (volatiles) are secondary plant metabolites that play crucial roles in the reproduction, defence, and interactions with other vegetation. They have been shown to exhibit a broad range of biological properties and have been investigated for antimicrobial and anticancer activities. In addition, they are thought be more environmentally friendly than many other synthetic chemicals 1. Despite these facts, their applications in the medical, food, and agricultural fields are considerably restricted due to their volatilities, instabilities, and aqueous insolubilities. Nanoparticle encapsulation of plant volatile organic compounds is regarded as one of the best strategies that could lead to the enhancement of the bioavailability and biological activity of the volatile compounds by overcoming their physical limitations and promoting their controlled release and cellular absorption. In this review, we will discuss the biosynthesis and analysis of plant volatile organic compounds, their biological activities, and limitations. Furthermore, different types of nanoparticle platforms used to encapsulate the volatiles and the biological efficacies of nanoencapsulated volatile organic compounds will be covered.

Biogenic silver nanoparticles are used for a number of applications due to their size, surface characteristics and strong antimicrobial properties. The present study aimed to investigate the synthesis of silver nanoparticles from the indigenous bacterial strain Bacillus sp. MB353 (PRJNA357966). Detailed characterization of silver nanoparticles was performed by UV–vis Spectrophotometer, FTIR, SEM and XRD. Biogenic silver nanoparticles were crystalline with average size 49−53 nm. These silver nanoparticles demonstrated good antibacterial activity against Gram-positive and Gram-negative bacteria (E. coli, Bacillus subtilis, Staphylococcus aureus, Klebsiella pneumoniae, Enterococcus faecium, Enterococcus faecalis and Streptomyces laurentii). The nanoparticles also showed excellent antifungal activity against Aspergillus niger, Aspergillus fumigatus, Fusarium soleni. The silver nanoparticles showed negligible antioxidant activity, but ROS generation pointed to a possible mode of antimicrobial activity. Incubation of silver nanoparticles with mammalian cell lines (Rhabdomyosarcomas and fibroblast) showed cell death and inhibition of proliferation. Cytotoxicity was most likely a result of ROS generation and changes in intracellular calcium levels. These findings suggested that biogenic silver nanoparticles could be used as alternative agents for biomedical purposes such as antibacterial and antifungal agents. However, given the effects on normal mammalian cells, it is probable that they could be used as anticancer agents if applied in targeted therapies.

Glioblastoma is a heterogeneous disease with multiple genotypic origins. Despite treatment protocols such as surgery, radiotherapy and chemotherapy, the prognosis for patients remains poor. This study investigates the cytotoxic and radiation dose-enhancing and radiosensitizing ability of five rare earth oxide nanoparticles, in two different immortalized mammalian cell lines; U-87 MG and Mo59K. Significant cytotoxicity was observed in U-87 MG cells when exposed to Nd

Mesoporous silica nanoparticles (MSNPs) have the potential to be used as antigen carriers due to their high surface areas and highly ordered pore network. We investigated the adsorption and desorption of diphtheria toxoid as a proof-of-concept. Two series of nanoparticles were prepared&mdash, (i) small pores (SP) (&lt, 10 nm) and (ii) large pores (LP) (&gt, 10 nm). SBA-15 was included as a comparison since this is commercially available and has been used in a large number of studies. External diameters of the particles ranged from 138 to 1509 nm, surface area from 632 to 1110 m2/g and pore size from 2.59 to 16.48 nm. Antigen loading was assessed at a number of different ratios of silica-to-antigen and at 4 &deg, C, 20 &deg, C and 37 &deg, C. Our data showed that protein adsorption by the SP series was in general consistently lower than that shown by the large pore series. Unloading was then examined at 4 &deg, C and a pH 1.2, 4.5, 6.8 and 7.4. There was a trend amongst the LP particles towards the smallest pores showing the lowest release of antigen. The stability of the MSNP: antigen complex was tested at two different storage temperatures, and storage in solution or after lyophilization. After 6 months there was negligible release from any of the particles under any of the storage conditions. The particles were also shown not to cause hemolysis.

Essential oils are volatile plant compounds that are biologically active and play an important role in natural plant protection. There are currently ∼3000 essential oils known, of which over 300 are commercially important for a variety of industries. In fact, the essential oil global market has been estimated to reach 13.94 billion USD with a demand of over 370,000 tons by 2024. These compounds have a wide variety of applications in agriculture, food and beverage, cosmetics, medicine, amongst other industries. A promising application of essential oils is as antimicrobials to target the vast number of diseases affecting crops. However, their volatile nature limits their effective use as free agents. To overcome this, we have investigated the use of mesoporous silica nanoparticles to protect essential oils from evaporation and degradation and to enhance their antimicrobial activity against bacterial phytopathogens. Silica nanoparticles were used due to their potential to be produced at an industrial scale and their biocompatibility. As a proof of concept, we evaluated 41 essential oils against bacterial phytopathogen Pseudomonas syringae pv. pisi, causative agent of pea bacterial blight. Additionally, we compared the effect of such essential oils against Pectobacterium carotovorum subsp. carotovorum and Pseudomonas fluorescens. Two of the most effective antimicrobials, cinnamon (Cinnamomum zeylanicum) and mustard (Brassica nigra) oils, were able to inhibit bacterial growth after 24 h at a concentration as low as 0.016% (v/v). Besides efficacy, the species-specificity of essential oils was demonstrated with >67% of oils tested displaying specificity towards pathogenic P. syringae pv. pisi over non-pathogenic Pseudomonas fluorescens. Furthermore, the encapsulation of essential oils into mesoporous silica nanoparticles (MSNPs) as a means of extending and improving their antimicrobial effect was found to enable a 10-fold increase in potency compared to the free essential oil. Cinnamaldehyde immobilised onto MSNPs proved to be the most effective antimicrobial, eliminating >99.8%, >99.9%, and >95% bacterial growth of P. fluorescens, P. syringae pv. pisi and P. carotovorum subsp. carotovorum, respectively. This system has the potential to be used to treat and prevent bacterial infections in crops and to enable a more controlled and effective exploitation of volatile compounds as antimicrobials.

Rachel A Morrison,1,* Malgorzata J Rybak-Smith,1,* James M Thompson,2 Bénédicte Thiebaut,3 Mark A Hill,2 Helen E Townley1,4 1Department of Engineering Science, 2Gray Laboratories, CRUK/MRC Oxford Institute for Radiation Oncology, University of Oxford, Oxford, 3Johnson Matthey, Technology Centre, Reading, Berkshire, 4Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, University of Oxford, Oxford, UK *These authors have contributed equally to this work Abstract: The aim of this study was to develop a manufacturing protocol for large-scale production of doped titania radiosensitizing nanoparticles (NPs) to establish their activity under hypoxia and to produce a multimodal radiosensitizing embolic particle for cancer treatment. We have previously shown that radiosensitizing NPs can be synthesized from titania doped with rare earth elements, especially gadolinium. To translate this technology to the clinic, a crucial step is to find a suitable, scalable, high-throughput method. Herein, we have described the use of flame spray pyrolysis (FSP) to generate NPs from titanium and gadolinium precursors to produce titania NPs doped with 5at% gadolinium. The NPs were fully characterized, and their capacity to act as radiosensitizers was confirmed by clonogenic assays. The integrity of the NPs in vitro was also ascertained due to the potentially adverse effects of free gadolinium in the body. The activity of the NPs was then studied under hypoxia since this is often a barrier to effective radiotherapy. In vitro radiosensitization experiments were performed with both the hypoxia mimetics deferoxamine and cobalt chloride and also under true hypoxia (oxygen concentration of 0.2%). It was shown that the radiosensitizing NPs were able to cause a significant increase in cell death even after irradiation under hypoxic conditions such as those found in tumors. Subsequently, the synthesized NPs were used to modify polystyrene embolization microparticles. The NPs were sintered to the surface of the microparticles by heating at 230°C for 15minutes. This resulted in a good coverage of the surface and to generate embolization particles that were shown to be radiosensitizing. Such multimodal particles could therefore result in occlusion of the tumor blood vessels in conjunction with localized reactive oxygen species generation, even under hypoxic conditions such as those found in the center of tumors. Keywords: cancer, ROS, reactive oxygen species, titania, multimodal

Nanoparticles may be used in vaccinology as an antigen delivery and/or an immunostimulant to enhance immunity. Porous silica has been identified as an effective adjuvant for more than a decade, and we have therefore investigated the take up rate by an immortalized macrophage-like cell line of a number of mesoporous silica nanoparticles (MSNPs) with differing diameter and pore size. The MSNPs were synthesized using a sol-gel reaction and post-synthesis removal of the template. The MSNPs showed a clear distribution in take up rate peaking at 217 nm, whereas a comparison with solid spherical nanoparticles showed a similar distribution peaking at 377 nm. The MSNPs were investigated before and after loading with antigen. Diphtheria toxoid was used as a proof-of-concept antigen and showed a peak macrophage internalization of 53.42% for loaded LP3 particles which had a diameter of 217.75 ± 5.44 nm and large 16.5 nm pores. Optimal MSNP sizes appeared to be in the 200–400 nm range, and larger pores showed better antigen loading. The mesoporous silica particles were shown to be generally biocompatible, and cell viability was not altered by the loading of particles with or without antigen.

In this review, we intend to highlight the progress which has been made in recent years around different types of smart activation nanosystems for cancer treatment. Conventional treatment methods, such as chemotherapy or radiotherapy, suffer from a lack of specific targeting and consequent off-target effects. This has led to the development of smart nanosystems which can effect specific regional and temporal activation. In this review, we will discuss the different methodologies which have been designed to permit activation at the tumour site. These can be divided into mechanisms which take advantage of the differences between healthy cells and cancer cells to trigger activation, and those which activate by a mechanism extrinsic to the cell or tumour environment.

Drug delivery using synthetic mesoporous nanomaterials, including porous silicon, has been extensively used to ameliorate the constraints currently experienced with conventional chemotherapy. Owing to the amazing potential, the silica based nanomaterials have been used widely. Nevertheless, synthetic nanomaterial involves high cost, lack of scalability, and the use of toxic substances limits its utilization. These issues can be overcome by the use of nature generated nanoscale materials, such as diatoms would serve as a boon for pharmaceutical industries. In this study we investigate the use of a mesoporous, biodegradable nanomaterial obtained from the natural silica found in the diatom species Amphora subtropica (AMPS) for drug delivery applications. AMPS cultures cleaned and chemically treated to obtain Amphora frustules (exoskeleton) (AF), followed by surface functionalization with chitosan (Chi). Results of our experiments demonstrate high drug loading, strong luminescence, biodegradable and biocompatible nature of the doxorubicin tethered diatom. Further, toxicity studies employing immortalized lung cancer cell line (A549) indicates sustained drug delivery and less toxic compared to the free doxorubicin (DOX), suggesting AF could be an excellent substitute for synthetic nanomaterials used in drug delivery applications.

Natural biocides, such as cinnamon (Cinnamomum zeylanicum) bark essential oil, have enormous potential as antimicrobials but are limited by their volatility and rapid degradation. To counteract this and to prolong the efficacy of the biocide, cinnamaldehyde (CNAD, the main bioactive compound of cinnamon essential oil) was encapsulated into mesoporous silica nanoparticles (MSNPs). The synthesised CNAD-MSNPs can be used to tackle the issue of global crop loss; every year, more than 40% of global food production (estimated at $500 billion USD) is lost to diseases. This is despite the annual use of over two million tonnes of pesticides. To address seed borne diseases, CNAD-MSNPs were incorporated into a sodium alginate seed coating. As a proof of concept, this system was tested against Pseudomonas syringae pv. pisi, the causative agent of pea bacterial blight, and demonstrated to increase the number of symptomless plants by 143.58% twenty days after sowing. Additionally, the concentration of CNAD present in the alginate coating was estimated to be

The prognosis of brain cancer glioblastoma (GBM) is poor, and despite intense research, there have been no significant improvements within the last decade. This stasis implicates the need for more novel therapeutic investigation. One such option is the use of nanoparticles (NPs), which can be beneficial due to their ability to penetrate the brain, overcome the blood–brain barrier and take advantage of the enhanced permeation and retention effect of GBM to improve specificity. Rare earth elements possess a number of interesting natural properties due to their unique electronic configuration, which may prove therapeutically advantageous in an NP formulation. The underexplored exciting potential for rare earth elements to augment the therapeutic potential of NPs in GBM treatment is discussed in this review.

peer-reviewed Physically or externally stimulated nanostructures often employ multimodality and show encouraging results at preclinical stage in cancer therapy. Specially designed smart nanostructures such as hybrid nanostructures are responsive to external physical stimuli such as light, magnetic field, electric, ultrasound, radio frequency, X-ray, etc. These physically responsive nanostructures have been widely explored as nonconventional innovative “nanotheranostics” in cancer therapies. Physically stimulated (particularly magnetic and light) nanotheranostics provide a unique combination of important properties to address key challenges in modern cancer therapy: (i) an active tumor targeting mechanism of therapeutic drugs driven by a physical force rather than passive antibody matching, (ii) an externally/remotely controlled drugs on-demand release mechanism, and (iii) a capability for advanced image guided tumor therapy and therapy monitoring. Although primarily addressed to the scientific community, this review offers valuable and accessible information for a wide range of readers interested in the current technological progress with direct relevance to the physics, chemistry, biomedical field, and theranostics. We herein cover magnetic and light-triggered modalities currently being developed for nonconventional cancer treatments. The physical basis of each modality is explained; so readers with a physics or, materials science background can easily grasp new developments in this field.

Nanoparticulate delivery of biocides has the potential to decrease levels of exposure to non-target organisms, and miminize long-term exposure that can promote the development of resistance. Silica nanoparticles are an ideal vehicle since they are inert, biocompatible, biodegradable, and thermally and chemically stable. Encapsulation of biocides within nanoparticulates can improve their stability and longevity and maximize the biocidal potential of hydrophobic volatile compounds. Herein, we have shown that the plant secondary metabolites allyl isothiocyanate and cinnamaldehyde demonstrated increased antimicrobial activity against Escherichia coli in planktonic form, when packaged into mesoporous silica nanoparticles. Furthermore, the biocide-loaded nanoparticles showed activity against Pseudomonas aeruginosa biofilms that have inherent resistance to antimicrobial agents. The delivery platform can also be expanded to traditional biocides and other non-conventional antimicrobial agents.

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma that is found in children and has a poor outcome for those with metastatic disease. Two histological groups have been distinguished - embryonal (ERMS) and alveolar (ARMS) forms. The ARMS subtype has higher rates of metastasis, as well as higher levels of ELMO1, which is thought to be involved in cell migration. Therefore, the knock-down of ELMO1 by targeted siRNA could provide a mechanism to prevent the metastatic behaviour of ARMS cells. However, challenges still lie in the delivery of nucleotides to a tumour site. Herein, we have described the use of a variety of mesoporous silica nanoparticles as a delivery system for siRNA that is specific for ELMO1 and shown the effective reduction in cell invasive behaviour in these cells.