Extracellular Vesicles-Mediated Bio-Orthogonal Catalysis in Growing Tumors.

Several studies have reported the successful use of bio-orthogonal catalyst nanoparticles (NPs) for cancer therapy. However, the delivery of the catalysts to the target tissues in vivo remains an unsolved challenge. The combination of catalytic NPs with extracellular vesicles (EVs) has been proposed as a promising approach to improve the delivery of therapeutic nanomaterials to the desired organs. In this study, we have developed a nanoscale bio-hybrid vector using a CO-mediated reduction at low temperature to generate ultrathin catalytic Pd nanosheets (PdNSs) as catalysts directly inside cancer-derived EVs. We have also compared their biodistribution with that of PEGylated PdNSs delivered by the EPR effect. Our results indicate that the accumulation of PdNSs in the tumour tissue was significantly higher when they were administered within the EVs compared to the PEGylated PdNSs. Conversely, the amount of Pd found in non-target organs (i.e., liver) was lowered. Once the Pd-based catalytic EVs were accumulated in the tumours, they enabled the activation of a paclitaxel prodrug demonstrating their ability to carry out bio-orthogonal uncaging chemistries in vivo for cancer therapy.

Enhanced Efficiency of Pd(0)-Based Single Chain Polymeric Nanoparticles for in Vitro Prodrug Activation by Modulating the Polymer's Microstructure.

Bioorthogonal catalysis employing transition metal catalysts is a promising strategy for the in situ synthesis of imaging and therapeutic agents in biological environments. The transition metal Pd has been widely used as a bioorthogonal catalyst, but bare Pd poses challenges in water solubility and catalyst stability in cellular environments. In this work, Pd(0) loaded amphiphilic polymeric nanoparticles are applied to shield Pd in the presence of living cells for the in situ generation of a fluorescent dye and anticancer drugs. Pd(0) loaded polymeric nanoparticles prepared by the reduction of the corresponding Pd(II)-polymeric nanoparticles are highly active in the deprotection of pro-rhodamine dye and anticancer prodrugs, giving significant fluorescence enhancement and toxigenic effects, respectively, in HepG2 cells. In addition, we show that the microstructure of the polymeric nanoparticles for scaffolding Pd plays a critical role in tuning the catalytic efficiency, with the use of the ligand triphenylphosphine as a key factor for improving the catalyst stability in biological environments.

Thioredoxin domain containing 5 is involved in the hepatic storage of squalene into lipid droplets in a sex-specific way.

Hepatic thioredoxin domain-containing 5 (TXNDC5) is a member of the protein disulfide isomerase family found associated with anti-steatotic properties of squalene and located in the endoplasmic reticulum and in lipid droplets. Considering that the latter are involved in hepatic squalene accumulation, the present research was aimed to investigate the role of TXNDC5 on hepatic squalene management in mice and in the AML12 hepatic cell line. Wild-type and TXNDC5-deficient (KO) mice were fed Western diets with or without 1% squalene supplementation for 6 weeks. In males, but not in females, absence of TXNDC5 blocked hepatic, but not duodenal, squalene accumulation. Hepatic lipid droplets were isolated and characterized using label-free LC-MS/MS analysis. TXNDC5 accumulated in this subcellular compartment of mice receiving squalene and was absent in TXNDC5-KO male mice. The latter mice were unable to store squalene in lipid droplets. CALR and APMAP were some of the proteins that responded to the squalene administration in all studied conditions. CALR and APMAP were positively associated with lipid droplets in the presence of squalene and they were decreased by the absence of TXNDC5. The increased squalene content was reproduced in vitro using AML12 cells incubated with squalene-loaded nanoparticles and this effect was not observed in an engineered cell line lacking TXNDC5. The phenomenon was also present when incubated in the presence of a squalene epoxidase inhibitor, suggesting a mechanism of squalene exocytosis involving CALR and APMAP. In conclusion, squalene accumulation in hepatic lipid droplets is sex-dependent on TXNDC5 that blocks its secretion.

Isolation of Extracellular Vesicles by a Microfluidic Platform to Diagnose and Monitor Pancreatic Cancer.

Exosomes are extracellular vesicles that are involved in cell-cell communication. Considering their bioavailability and accessibility in all the body fluids (including the blood, semen, breast milk, saliva, and urine), their use has been proposed as an alternative noninvasive tool for the diagnosis, monitoring, and prognosis of several diseases, including cancer. The isolation of exosomes and their subsequent analysis are emerging as a promising technique in diagnostics and personalized medicine. The most widely employed isolation procedure is differential ultracentrifugation, but this approach is laborious, time-consuming, and expensive and with limited isolation yield. Microfluidic devices are now emerging as novel platforms for exosome isolation, which is a low cost technology and enables high purity and fast treatment of exosome isolation. Our approach describes a microfluidic device that enables inflow capture and separation from whole blood using antibody-functionalized magnetic nanoparticles. This device allows isolation of pancreatic cancer-derived exosomes from whole blood without the need of any pretreatment, resulting in a high sensitivity.

X-ray Photoelectron Spectroscopy (XPS) Analysis of Nitrogen Environment in Small Extracellular Vesicle Membranes: A Potential Novel Technique with Application for Cancer Screening.

Small extracellular vesicle (EV) membranes display characteristic protein-lipidic composition features that are related to their cell of origin, providing valuable clues regarding their parental cell composition and real-time state. This could be especially interesting in the case of cancer cell-derived EVs, as their membranes could serve as valuable tools in liquid biopsy applications and to detect changes in the tumor malignancy. X-Ray Photoelectron Spectroscopy (XPS) is a powerful surface analysis technique able to detect every chemical element present, being also sensitive to their chemical environment. Here we explore the use of XPS as a fast technique to characterize EV membrane composition, with possible application in cancer research. Notably, we have focused on the nitrogen environment as an indicator of the relative abundance of pyridine-type bonding, primary, secondary and tertiary amines. Specifically, we have analyzed how tumoral and healthy cells have different nitrogen chemical environments that can indicate the presence or absence of malignancy. In addition, a collection of human serum samples from cancer patients and healthy donors was also analyzed. The differential XPS analysis of EVs collected from patients confirmed that the patterns of amine evolution could be related to markers of cancer disease, opening the possibility of their use as a non-invasive blood biomarker.

Superfluorinated Extracellular Vesicles for In Vivo Imaging by 19F-MRI.

Extracellular vesicles (EVs) play a crucial role in cell-to-cell communication and have great potential as efficient delivery vectors. However, a better understanding of EV in vivo behavior is hampered by the limitations of current imaging tools. In addition, chemical labels present the risk of altering the EV membrane features and, thus, in vivo behavior. 19F-MRI is a safe bioimaging technique providing selective images of exogenous probes. Here, we present the first example of fluorinated EVs containing PERFECTA, a branched molecule with 36 magnetically equivalent 19F atoms. A PERFECTA emulsion is given to the cells, and PERFECTA-containing EVs are naturally produced. PERFECTA-EVs maintain the physicochemical features, morphology, and biological fingerprint as native EVs but exhibit an intense 19F-NMR signal and excellent 19F relaxation times. In vivo 19F-MRI and tumor-targeting capabilities of stem cell-derived PERFECTA-EVs are also proved. We propose PERFECTA-EVs as promising biohybrids for imaging biodistribution and delivery of EVs throughout the body.

Iron inactivation by Sporobolomyces ruberrimus and its potential role in plant metal stress protection. An in vitro study.

The endophytic Basidiomycete Sporobolomyces ruberrimus protects its host Arabidopsis arenosa against metal toxicity. Plants inoculated with the fungus yielded more biomass and exhibited significantly fewer stress symptoms in medium mimicking mine dump conditions (medium supplemented with excess of Fe, Zn and Cd). Aside from fine-tuning plant metal homeostasis, the fungus was capable of precipitating Fe in the medium, most likely limiting host exposure to metal toxicity. The precipitated residue was identified by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-Ray Diffraction (XRD) and electron microscopy (SEM/TEM) with energy dispersive X-Ray analysis (EDX/SAED) techniques. The performed analyses revealed that the fungus transforms iron into amorphous (oxy)hydroxides and phosphates and immobilizes them in the form of a precipitate changing Fe behaviour in the MSR medium. Moreover, the complexation of free Fe ions by fungi could be obtained by biomolecules such as lipids, proteins, or biosynthesized redox-active molecules.

In Cellulo Bioorthogonal Catalysis by Encapsulated AuPd Nanoalloys: Overcoming Intracellular Deactivation.

Bioorthogonal metallocatalysis has opened up a xenobiotic route to perform nonenzymatic catalytic transformations in living settings. Despite their promising features, most metals are deactivated inside cells by a myriad of reactive biomolecules, including biogenic thiols, thereby limiting the catalytic functioning of these abiotic reagents. Here we report the development of cytocompatible alloyed AuPd nanoparticles with the capacity to elicit bioorthogonal depropargylations with high efficiency in biological media. We also show that the intracellular catalytic performance of these nanoalloys is significantly enhanced by protecting them following two different encapsulation methods. Encapsulation in mesoporous silica nanorods resulted in augmented catalyst reactivity, whereas the use of a biodegradable PLGA matrix increased nanoalloy delivery across the cell membrane. The functional potential of encapsulated AuPd was demonstrated by releasing the potent chemotherapy drug paclitaxel inside cancer cells. Nanoalloy encapsulation provides a novel methodology to develop nanoreactors capable of mediating new-to-life reactions in cells.

Liposomal Binuclear Ir(III)-Cu(II) Coordination Compounds with Phosphino-Fluoroquinolone Conjugates for Human Prostate Carcinoma Treatment.

Novel heteronuclear IrIII-CuII coordination compounds ([Ir(η5-Cp*)Cl2Pcfx-Cu(phen)](NO3)·1.75(CH3OH)·0.75(H2O) (1), [Ir(η5-Cp*)Cl2Pnfx-Cu(phen)](NO3)·1.75(CH3OH)·0.75(H2O) (2), [Ir(η5-Cp*)Cl2Plfx-Cu(phen)](NO3)·1.3(H2O)·1.95(CH3OH) (3), [Ir(η5-Cp*)Cl2Psfx-Cu(phen)] (4)) bearing phosphines derived from fluoroquinolones, namely, sparfloxacin (Hsfx), ciprofloxacin (Hcfx), lomefloxacin (Hlfx), and norfloxacin (Hnfx), have been synthesized and studied as possible anticancer chemotherapeutics. All compounds have been characterized by electrospray ionization mass spectrometry (ESI-MS), a number of spectroscopic methods (i.e., IR, fluorescence, and electron paramagnetic resonance (EPR)), cyclic voltammetry, variable-temperature magnetic susceptibility measurements, and X-ray diffractometry. The coordination geometry of IrIII in all complexes adopts a characteristic piano-stool geometry with the η5-coordinated and three additional sites occupied by two chloride and phosphine ligands, while CuII ions in complexes 1 and 2 form a distorted square-pyramidal coordination geometry, and in complex 3, the coordination geometry around CuII ions is a distorted octahedron. Interestingly, the crystal structure of [Ir(η5-Cp*)Cl2Plfx-Cu(phen)] features the one-dimensional (1D) metal-organic polymer. Liposomes loaded with redox-active and fluorescent [Ir(η5-Cp*)Cl2Pcfx-Cu(phen)] (1L) have been prepared to increase water solubility and minimize serious systemic side effects. It has been proven, by confocal microscopy and an inductively coupled plasma mass spectrometry (ICP-MS) analysis, that the liposomal form of compound 1 can be effectively accumulated inside human lung adenocarcinoma and human prostate carcinoma cells with selective localization in nuclei. A cytometric analysis showed dominance of apoptosis over the other cell death types. Furthermore, the investigated nanoformulations induced changes in the cell cycle, leading to S phase arrest in a dose-dependent manner. Importantly, in vitro anticancer action on three-dimensional (3D) multicellular tumor spheroids has been demonstrated.

Exosomes loaded with ultrasmall Pt nanoparticles: a novel low-toxicity alternative to cisplatin.

BACKGROUND: Platinum nanoparticles have been demonstrated to have excellent anticancer properties. However, because of the lack of specificity they must be delivered to the tumor in amounts sufficient to reach the desired therapeutic objectives. Interestingly, exosomes are considered as excellent natural selective delivery nanotools, but until know their targeting properties have not being combined with the anticancer properties of platinum nanoparticles. RESULTS: In this work we combine the targeting capabilities of exosomes and the antitumoral properties of ultrasmall (< 2 nm) platinum nanoparticles as a novel, low toxicity alternative to the use of cisplatin. A mild methodology based on the room temperature CO-assisted in situ reduction of Pt2+ precursor was employed to preserve the integrity of exosomes, while generating ultrasmall therapeutic PtNPs directly inside the vesicles. The resulting PtNPs-loaded exosomes constitute a novel hybrid bioartificial system that was readily internalized by the target cells inducing antiproliferative response, as shown by flow cytometry and microscopy experiments in vitro. In vivo Pt-Exos showed antitumoral properties similar to that of cisplatin but with a strongly reduced or in some cases no toxic effect, highlighting the advantages of this approach and its potential for translation to the clinic. CONCLUSIONS: In this study, a nanoscale vector based on ultrasmall PtNPs and exosomes has been created exhibiting antitumoral properties comparable or higher to those of the FDA approved cisplatin. The preferential uptake of PtNPs mediated by exosomal transfer between certain cell types has been exploited to create a selective antitumoral novel bioartificial system. We have demonstrated their anticancer properties both in vitro and in vivo comparing the results obtained with the administration of equivalent amounts of cisplatin, and showing a spectacular reduction of toxicity.

Silver Nanoparticles-Polyethyleneimine-Based Coatings with Antiviral Activity against SARS-CoV-2: A New Method to Functionalize Filtration Media.

The use of face masks and air purification systems has been key to curbing the transmission of SARS-CoV-2 aerosols in the context of the current COVID-19 pandemic. However, some masks or air conditioning filtration systems are designed to remove large airborne particles or bacteria from the air, being limited their effectiveness against SARS-CoV-2. Continuous research has been aimed at improving the performance of filter materials through nanotechnology. This article presents a new low-cost method based on electrostatic forces and coordination complex formation to generate antiviral coatings on filter materials using silver nanoparticles and polyethyleneimine. Initially, the AgNPs synthesis procedure was optimized until reaching a particle size of 6.2 ± 2.6 nm, promoting a fast ionic silver release due to its reduced size, obtaining a stable colloid over time and having reduced size polydispersity. The stability of the binding of the AgNPs to the fibers was corroborated using polypropylene, polyester-viscose, and polypropylene-glass spunbond mats as substrates, obtaining very low amounts of detached AgNPs in all cases. Under simulated operational conditions, a material loss less than 1% of nanostructured silver was measured. SEM micrographs demonstrated high silver distribution homogeneity on the polymer fibers. The antiviral coatings were tested against SARS-CoV-2, obtaining inactivation yields greater than 99.9%. We believe our results will be beneficial in the fight against the current COVID-19 pandemic and in controlling other infectious airborne pathogens.

Trojan pH-Sensitive Polymer Particles Produced in a Continuous-Flow Capillary Microfluidic Device Using Water-in-Oil-in-Water Double-Emulsion Droplets.

A facile and robust microfluidic method to produce nanoparticle-in-microparticle systems (Trojan systems) is reported as a delivery vector for the oral administration of active pharmaceutical ingredients. The microfluidic system is based on two coaxial capillaries that produce monodisperse water-in-oil-in-water (W/O/W) double emulsions in a highly controlled fashion with precise control over the resulting particle structure, including the core and shell dimensions. The influence of the three phase flow rates, pH and drying process on the formation and overall size is evaluated. These droplets are then used as templates for the production of pH-sensitive Trojan microparticles after solvent evaporation. The shell of Trojan microparticles is made of Eudragit®, a methacrylic acid-ethyl acrylate copolymer that would enable the Trojan microparticle payload to first pass through the stomach without being degraded and then dissolve in the intestinal fluid, releasing the inner payload. The synthesis of the pH-sensitive Trojan microparticles was also compared with a conventional batch production method. The payloads considered in this work were different in nature: (1) fluorescein, to validate the feasibility of the polymeric shell to protect the payload under gastric pH; (2) poly(D,L-lactic acid/glycolic acid)-PLGA nanoparticles loaded with the antibiotic rifampicin. These PLGA nanoparticles were produced also using a microfluidic continuous process and (3) PLGA nanoparticles loaded with Au nanoparticles to trace the PLGA formulation under different environments (gastric and intestinal), and to assess whether active pharmaceutical ingredient (API) encapsulation in PLGA is due efficiently. We further showed that Trojan microparticles released the embedded PLGA nanoparticles in contact with suitable media, as confirmed by electron microscopy. Finally, the results show the possibility of developing Trojan microparticles in a continuous manner with the ability to deliver therapeutic nanoparticles in the gastrointestinal tract.

Squalene Loaded Nanoparticles Effectively Protect Hepatic AML12 Cell Lines against Oxidative and Endoplasmic Reticulum Stress in a TXNDC5-Dependent Way.

Virgin olive oil, the main source of fat in the Mediterranean diet, contains a substantial amount of squalene which possesses natural antioxidant properties. Due to its highly hydrophobic nature, its bioavailability is reduced. In order to increase its delivery and potentiate its actions, squalene has been loaded into PLGA nanoparticles (NPs). The characterization of the resulting nanoparticles was assessed by electron microscopy, dynamic light scattering, zeta potential and high-performance liquid chromatography. Reactive oxygen species (ROS) generation and cell viability assays were carried out in AML12 (alpha mouse liver cell line) and a TXNDC5-deficient AML12 cell line (KO), which was generated by CRISPR/cas9 technology. According to the results, squalene was successfully encapsulated in PLGA NPs, and had rapid and efficient cellular uptake at 30 µM squalene concentration. Squalene reduced ROS in AML12, whereas ROS levels increased in KO cells and improved cell viability in both when subjected to oxidative stress by significant induction of Gpx4. Squalene enhanced cell viability in ER-induced stress by decreasing Ern1 or Eif2ak3 expressions. In conclusion, TXNDC5 shows a crucial role in regulating ER-induced stress through different signaling pathways, and squalene protects mouse hepatocytes from oxidative and endoplasmic reticulum stresses by several molecular mechanisms depending on TXNDC5.

Transfer of photothermal nanoparticles using stem cell derived small extracellular vesicles for in vivo treatment of primary and multinodular tumours.

The main current challenges in oncology are (1) avoiding systemic side effects in therapy, and (2) developing alternative treatment strategies for metastatic tumours. Nanomedicine was assumed to provide answers to these issues, but delivering enough therapeutic nanoparticles (NPs) to tumours still remains a huge challenge in nanomaterials-based treatments. Extracellular vesicles (EVs) play a key role in cell communication processes and can be combined with nanomaterials to improve their targeting capabilities. In this work, we leverage the ability of EVs derived from stem cells to reach tumour areas successfully, being used as delivery vehicles for nanoparticles acting as hyperthermia agents. Once small extracellular vesicles (sEVs) loaded with NIR-sensitive hollow gold NPs reached primary subcutaneous solid tumours, they were irradiated with a NIR laser and almost complete tumour remission was obtained. More interestingly, those sEV vehicles were also able to reach multinodular areas similar to those on advanced metastatic phases, eradicating most tumour growth regions in multiple cancerous nodules located in the pancreas region.

Decoration of Squalenoyl-Gemcitabine Nanoparticles with Squalenyl-Hydroxybisphosphonate for the Treatment of Bone Tumors.

Therapeutic perspectives of bone tumors such as osteosarcoma remain restricted due to the inefficacy of current treatments. We propose here the construction of a novel anticancer squalene-based nanomedicine with bone affinity and retention capacity. A squalenyl-hydroxybisphosphonate molecule was synthetized by chemical conjugation of a 1-hydroxyl-1,1-bisphosphonate moiety to the squalene chain. This amphiphilic compound was inserted onto squalenoyl-gemcitabine nanoparticles using the nanoprecipitation method. The co-assembly led to nanoconstructs of 75 nm, with different morphology and colloidal properties. The presence of squalenyl-hydroxybisphosphonate enhanced the nanoparticles binding affinity for hydroxyapatite, a mineral present in the bone. Moreover, the in vitro anticancer activity was preserved when tested in commercial and patient-treated derived pediatric osteosarcoma cells. Further in vivo studies will shed light on the potential of these nanomedicines for the treatment of bone sarcomas.

A minimally-masked inactive prodrug of panobinostat that is bioorthogonally activated by gold chemistry.

The recent incorporation of Au chemistry in the bioorthogonal toolbox has opened up new opportunities to deliver biologically independent reactions in living environments. Herein we report that the O-propargylation of the hydroxamate group of the potent HDAC inhibitor panobinostat leads to a vast reduction of its anticancer properties (>500-fold). We also show that this novel prodrug is converted back into panobinostat in the presence of Au catalysts in vitro and in cell culture.

Continuous selective deoxygenation of palm oil for renewable diesel production over Ni catalysts supported on Al2O3 and La2O3-Al2O3.

The present study provides, for the first time in the literature, a comparative assessment of the catalytic performance of Ni catalysts supported on γ-Al2O3 and γ-Al2O3 modified with La2O3, in a continuous flow trickle bed reactor, for the selective deoxygenation of palm oil. The catalysts were prepared via the wet impregnation method and were characterized, after calcination and/or reduction, by N2 adsorption/desorption, XRD, NH3-TPD, CO2-TPD, H2-TPR, H2-TPD, XPS and TEM, and after the time-on-stream tests, by TGA, TPO, Raman and TEM. Catalytic experiments were performed between 300-400 °C, at a constant pressure (30 bar) and different LHSV (1.2-3.6 h-1). The results show that the incorporation of La2O3 in the Al2O3 support increased the Ni surface atomic concentration (XPS), affected the nature and abundance of surface basicity (CO2-TPD), and despite leading to a drop in surface acidity (NH3-TPD), the Ni/LaAl catalyst presented a larger population of medium-strength acid sites. These characteristics helped promote the SDO process and prevented extended cracking and the formation of coke. Thus, higher triglyceride conversions and n-C15 to n-C18 hydrocarbon yields were achieved with the Ni/LaAl at lower reaction temperatures. Moreover, the Ni/LaAl catalyst was considerably more stable during 20 h of time-on-stream. Examination of the spent catalysts revealed that both carbon deposition and degree of graphitization of the surface coke, as well as, the extent of sintering were lower on the Ni/LaAl catalyst, explaining its excellent performance during time-on-stream.

Nondestructive production of exosomes loaded with ultrathin palladium nanosheets for targeted bio-orthogonal catalysis.

The use of exosomes as selective delivery vehicles of therapeutic agents, such as drugs or hyperthermia-capable nanoparticles, is being intensely investigated on account of their preferential tropism toward their parental cells. However, the methods used to introduce a therapeutic load inside exosomes often involve disruption of their membrane, which may jeopardize their targeting capabilities, attributed to their surface integrins. On the other hand, in recent years bio-orthogonal catalysis has emerged as a new tool with a myriad of potential applications in medicine. These bio-orthogonal processes, often based on Pd-catalyzed chemistry, would benefit from systems capable of delivering the catalyst to target cells. It is therefore highly attractive to combine the targeting capabilities of exosomes and the bio-orthogonal potential of Pd nanoparticles to create new therapeutic vectors. In this protocol, we provide detailed information on an efficient procedure to achieve a high load of catalytically active Pd nanosheets inside exosomes, without disrupting their membranes. The protocol involves a multistage process in which exosomes are first harvested, subjected to impregnation with a Pd salt precursor followed by a mild reduction process using gas-phase CO, which acts as both a reducing and growth-directing agent to produce the desired nanosheets. The technology is scalable, and the protocol can be conducted by any researcher having basic biology and chemistry skills in ~3 d.

Towards plant-mediated chemistry - Au nanoparticles obtained using aqueous extract of Rosa damascena and their biological activity in vitro.

An eco-friendly, efficient, and controlled synthesis of gold nanoparticles with application of the aqueous extract of Rosa damascena (Au@RD NPs) without using any other reducing agents was studied. Au@RD NPs of narrow size distribution were characterized by UV-vis and FT-IR spectroscopies, transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, particle size analysis, and zeta potential measurements. In vitro stability experiments revealed that the Au@RD NPs were stable for over a year (pH ~ 3.5), proving a significant stabilizing potential of the aqueous RD extract. The high total content of polyphenols, flavonoids, and reducing sugars along with the powerful antioxidant activity of the RD extract was determined by spectroscopic and analytical methods. Colloids prepared from the purified and lyophilized Au@RD NPs (electrokinetic potential of ca. -33 mV) were stable for at least 24 h under terms similar to physiological conditions (pH = 7.4, PBS). The in vitro cytotoxicity of Au@RD NPs was investigated against peripheral blood mononuclear lymphocytes (PBML), acute promyelocytic leukemia (HL60), and human lung adenocarcinoma (A549). Selective cytotoxicity of Au@RD NPs towards cancer cells (HL60, A549) over normal cells (PBML) in vitro was explicitly demonstrated by viability assays. Comet assay revealed a higher level of DNA damages in cancer cells when compared with normal ones. Apoptotic death in cancer cells was proved by measuring caspases activity. Thus, the developed Au@RD NPs, obtained by the plant-mediated green synthesis, are attractive hybrid materials for the medical applications combining two active components - metal nanoparticles platform and plant-derived metabolites.

Continuous Single-Phase Synthesis of [Au25(Cys)18] Nanoclusters and their Photobactericidal Enhancement.

Thiolate-gold nanoclusters have various applications. However, most of the synthesis methods require prolonged synthesis times from several hours to days. In the present study, we report a rapid synthesis method for [Au25(Cys)18] nanoclusters and their application for photobactericidal enhancement. For [Au25(Cys)18] synthesis, we employed a tube-in-tube membrane reactor using CO as a reducing agent at elevated temperatures. This approach allows continuous generation of high-quality [Au25(Cys)18] within 3 min. Photobactericidal tests against Staphylococcus aureus showed that crystal violet-treated polymer did not have photobactericidal activity, but addition of [Au25(Cys)18] in the treated polymer demonstrated a potent photobactericidal activity at a low white light flux, resulting in >4.29 log reduction in viable bacteria numbers. Steady-state and time-resolved photoluminescence spectroscopies demonstrated that after light irradiation, photoexcited electrons in crystal violet flowed to [Au25(Cys)18] in the silicone, suggesting that redox reaction from [Au25(Cys)18] enhanced the photobactericidal activity. Stability tests revealed that leaching of crystal violet and [Au25(Cys)18] from the treated silicone was negligible and cyclic testing showed that the silicone maintained a strong photobactericidal activity after repeated use.