Encapsulation of Doxorubicin in Furcellaran/Chitosan Nanocapsules by Layer-by-Layer Technique for Selectively Controlled Drug Delivery.

Minimization of drug side effects is a hallmark of advanced targeted therapy. Herein we describe the synthesis of polysaccharide-based nanocapsules prepared from furcellaran and chitosan via layer-by-layer deposition using electrostatic interaction. Using doxorubicin as a model drug, prepared nanocapsules showed excellent drug loading properties and release influence by pH and stability. Targeted delivery of doxorubicin was achieved by nanocapsule surface modification using homing peptide (seq SMSIARLC). The synthesized nanocapsules possess excellent compatibility to eukaryotic organisms. In the case of nonmalignant cells (PNT1A and HEK-293), toxicity tests revealed the absences of DNA fragmentation, apoptosis, necrosis, and also disruption of erythrocyte membranes. In contrast, results from treatment of malignant cell lines (MDA-MB-231 and PC3) indicate good anticancer effects of synthesized bionanomaterial. Internalization studies revealed the nanocapsule's ability to enter the malignant cell lines by endocytosis and triggering the apoptosis. The occurrence of apoptosis is mostly connected to the presence of ROS and inability of DNA damage reparation. Additionally, the obtained results strongly indicate that peptide modification increases the speed of nanocapsule internalization into malignant cell lines while simultaneously nonmalignant cell lines are untouched by nanocapsules highlighting the strong selectivity of the peptide.

Soil protein as a potential antimicrobial agent against methicillin -resistant Staphylococcus aureus.

Recently, the interest is increasing to find alternatives to replace the usage of antibiotics since their massive and improper usage enhance the antibiotic resistance in human pathogens. In this study, for the first time we showed that the soil proteins have very high antibacterial activity (98% of growth inhibition) against methicillin resistant Staphylococcus aureus (MRSA), one of the most threatening human pathogens. We found that the protein extract (C3) from the forest with past intensive management showed higher antibacterial activity than that of unmanaged forest. The MIC and IC50 were found to be 30 and 15.0 µg protein g-1 dry soil respectively. C3 was found to kill the bacteria by cell wall disruption and genotoxicity which was confirmed by optical and fluorescent microscopy and comet assay. According to qPCR study, the mecA (the antibiotic resistant gene) expression in MRSA was found to be down-regulated after C3 treatment. In contrast, C3 showed no hemolytic toxicity on human red blood cells which was confirmed by hemolytic assay. According to ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS), 144 proteins were identified in C3 among which the majority belonged to Gram negative bacteria (45.8%). Altogether, our results will help to develop novel, cost-effective, non-toxic and highly efficient antibacterial medicines from natural sources against antibiotic resistant infections.

A Novel Ruthenium Based Coordination Compound Against Pathogenic Bacteria.

The current epidemic of antibiotic-resistant infections urges to develop alternatives to less-effective antibiotics. To assess anti-bacterial potential, a novel coordinate compound (RU-S4) was synthesized using ruthenium-Schiff base-benzimidazole ligand, where ruthenium chloride was used as the central atom. RU-S4 was characterized by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and Raman spectroscopy. Antibacterial effect of RU-S4 was studied against Staphylococcus aureus (NCTC 8511), vancomycin-resistant Staphylococcus aureus (VRSA) (CCM 1767), methicillin-resistant Staphylococcus aureus (MRSA) (ST239: SCCmecIIIA), and hospital isolate Staphylococcus epidermidis. The antibacterial activity of RU-S4 was checked by growth curve analysis and the outcome was supported by optical microscopy imaging and fluorescence LIVE/DEAD cell imaging. In vivo (balb/c mice) infection model prepared with VRSA (CCM 1767) and treated with RU-S4. In our experimental conditions, all infected mice were cured. The interaction of coordination compound with bacterial cells were further confirmed by cryo-scanning electron microscope (Cryo-SEM). RU-S4 was completely non-toxic against mammalian cells and in mice and subsequently treated with synthesized RU-S4.

Functional Analysis of Novicidin Peptide: Coordinated Delivery System for Zinc via Schiff Base Ligand.

Novicidin (NVC), is a membrane-penetrating peptide, which forms a stable complex with Zn-Schiff base with interesting antitumor selectivity. We studied NVC derivatives to determine functional roles of key amino acids in toxicity, helicity, and binding of the Zn-Schiff base complex. Trimmed derivatives highlighted the role of peptide length and helicity in toxicity and membrane penetration. The removal of Lys from position 1 and 2 strongly increases the ability to disrupt the membranes. The trimming of the N-terminal residues significantly increases the stability of peptide helicity enhancing penetrating properties. Gly residue derivatives undermined a role of peptide bending in membrane penetration and toxicity. After the substitution of the central Gly derivatives with Ile or Lys, the peptides retained toxicity. These results illustrate the minor role of central helix bending in NVC toxicity. Binding-site-peptide derivatives identified His residue as the sole Zn-Schiff base binding site and eliminated the role of other aromatic residues.

Effect of arsenic (III and V) on oxidative stress parameters in resistant and susceptible Staphylococcus aureus.

The presented study deals with the observation of properties of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) in the toxic arsenic environment and influence of arsenic on antioxidant capacity. Two forms of arsenic (As(III), As(V)) with different concentrations were used for induction of the oxidative stress in tested strains. Microbiological methods showed that the growth inhibition of MSSA was higher than that of MRSA in presence of both arsenic ions. As(III) showed 24% and 33% higher anti-microbial effects than As(V) against MSSA and MRSA respectively. A similar result was found also in the experiment of reduction of biofilm-formation. By using spectrophotometry, it was revealed that As(III) induced higher antioxidant production in both bacterial cultures. Methicillin-susceptible S. aureus produced an app. 50 mg equivalent of gallic acid (GAE/1 mg of protein) and MRSA produced an app. 15 mg of GAE/1 mg of protein. The productions of metallothionein in MSSA and MRSA were decreased up to 62.41% and 55.84% respectively in presence of As ions. Reduction of As(III) and As(V) concentrations leads to a decrease in antioxidant production and increased the formation of metallothionein. All of these changes in the results were found to be significant statistically. Taken together, these experiments proved that in comparison with MSSA, MRSA is less susceptible not only to the antimicrobial effects of antibiotics but also against effects caused by metalloids, as arsenic. Thus, it can be stated that MRSA abounds with complex defensive mechanisms, which may in the future constitute significant problem in the efficiency of antibiotics alternatives as metal ions or nanoparticles.

Improving cytocompatibility of CdTe quantum dots by Schiff-base-coordinated lanthanides surface doping.

BACKGROUND: Suitable fluorophores are the core of fluorescence imaging. Among the most exciting, yet controversial, labels are quantum dots (QDs) with their unique optical and chemical properties, but also considerable toxicity. This hinders QDs applicability in living systems. Surface chemistry has a profound impact on biological behavior of QDs. This study describes a two-step synthesis of QDs formed by CdTe core doped with Schiff base ligand for lanthanides [Ln (Yb3+, Tb3+ and Gd3+)] as novel cytocompatible fluorophores. RESULTS: Microwave-assisted synthesis resulted in water-soluble nanocrystals with high colloidal and fluorescence stability with quantum yields of 40.9-58.0%. Despite induction of endocytosis and cytoplasm accumulation of Yb- and TbQDs, surface doping resulted in significant enhancement in cytocompatibility when compared to the un-doped CdTe QDs. Furthermore, only negligible antimigratory properties without triggering formation of reactive oxygen species were found, particularly for TbQDs. Ln-doped QDs did not cause observable hemolysis, adsorbed only a low degree of plasma proteins onto their surface and did not possess significant genotoxicity. To validate the applicability of Ln-doped QDs for in vitro visualization of receptor status of living cells, we performed a site-directed conjugation of antibodies towards immuno-labeling of clinically relevant target-human norepinephrine transporter (hNET), over-expressed in neuroendocrine tumors like neuroblastoma. Immuno-performance of modified TbQDs was successfully tested in distinct types of cells varying in hNET expression and also in neuroblastoma cells with hNET expression up-regulated by vorinostat. CONCLUSION: For the first time we show that Ln-doping of CdTe QDs can significantly alleviate their cytotoxic effects. The obtained results imply great potential of Ln-doped QDs as cytocompatible and stable fluorophores for various bio-labeling applications.

Alternative Synthesis Route of Biocompatible Polyvinylpyrrolidone Nanoparticles and Their Effect on Pathogenic Microorganisms.

Herein we describe a novel alternative synthesis route of polyvinylpyrrolidone nanoparticles using salting-out method at a temperature close to polyvinylpyrrolidone decomposition. At elevated temperatures, the stability of polyvinylpyrrolidone decreases and the opening of pyrrolidone ring fractions occurs. This leads to cross-linking process, where separate units of polyvinylpyrrolidone interact among themselves and rearrange to form nanoparticles. The formation/stability of these nanoparticles was confirmed by transmission electron microscopy, X-ray photoelectron spectroscopy, mass spectrometry, infrared spectroscopy, and spectrophotometry. The obtained nanoparticles possess exceptional biocompatibility. No toxicity and genotoxicity was found in normal human prostate epithelium cells (PNT1A) together with their high hemocompatibility. The antimicrobial effects of polyvinylpyrrolidone nanoparticles were tested on bacterial strains isolated from the wounds of patients suffering from hard-to-heal infections. Molecular analysis (qPCR) confirmed that the treatment can induce the regulation of stress-related survival genes. Our results strongly suggest that the polyvinylpyrrolidone nanoparticles have great potential to be developed into a novel antibacterial compound.

Electrochemical sensing of etoposide using carbon quantum dot modified glassy carbon electrode.

In this study, enhancement of the electrochemical signals of etoposide (ETO) measured by differential pulse voltammetry (DPV) by modifying a glassy carbon electrode (GCE) with carbon quantum dots (CQDs) is demonstrated. In comparison with a bare GCE, the modified GCE exhibited a higher sensitivity towards electrochemical detection of ETO. The lowest limit of detection was observed to be 5 nM ETO. Furthermore, scanning electron microscopy (SEM), fluorescence microscopy (FM), and electrochemical impedance spectroscopy (EIS) were employed for the further study of the working electrode surface after the modification with CQDs. Finally, the GCE modified with CQDs under optimized conditions was used to analyse real samples of ETO in the prostate cancer cell line PC3. After different incubation times (1, 3, 6, 9, 12, 18 and 24 h), these samples were then prepared prior to electrochemical detection by the GCE modified with CQDs. High performance liquid chromatography with an electrochemical detection method was employed to verify the results from the GCE modified with CQDs.

Transport phenomena of nanoparticles in plants and animals/humans.

The interaction of a plethora nanoparticles with major biota such as plants and animals/humans has been the subject of various multidisciplinary studies with special emphasis on toxicity aspects. However, reports are meager on the transport phenomena of nanoparticles in the plant-animal/human system. Since plants and animals/humans are closely linked via food chain, discussion is imperative on the main processes and mechanisms underlying the transport phenomena of nanoparticles in the plant-animal/human system, which is the main objective of this paper. Based on the literature appraised herein, it is recommended to perform an exhaustive exploration of so far least explored aspects such as reproducibility, predictability, and compliance risks of nanoparticles, and insights into underlying mechanisms in context with their transport phenomenon in the plant-animal/human system. The outcomes of the suggested studies can provide important clues for fetching significant benefits of rapidly expanding nanotechnology to the plant-animal/human health-improvements and protection as well.

Induction of Laccase, Lignin Peroxidase and Manganese Peroxidase Activities in White-Rot Fungi Using Copper Complexes.

Ligninolytic enzymes, such as laccase, lignin peroxidase and manganese peroxidase, are biotechnologically-important enzymes. The ability of five white-rot fungal strains Daedaleopsis confragosa, Fomes fomentarius, Trametes gibbosa, Trametes suaveolens and Trametes versicolor to produce these enzymes has been studied. Three different copper(II) complexes have been prepared ((Him)[Cu(im)4(H2O)2](btc)·3H2O, where im = imidazole, H3btc = 1,3,5-benzenetricarboxylic acid, [Cu3(pmdien)3(btc)](ClO4)3·6H2O) and [Cu3(mdpta)3(btc)](ClO4)3·4H2O, where pmdien = N,N,N',N'',N''-pentamethyl-diethylenetriamine and mdpta = N,N-bis-(3-aminopropyl)methyl- amine), and their potential application for laccase and peroxidases induction have been tested. The enzyme-inducing activities of the complexes were compared with that of copper sulfate, and it has been found that all of the complexes are suitable for the induction of laccase and peroxidase activities in white-rot fungi; however, the newly-synthesized complex M1 showed the greatest potential for the induction. With respect to the different copper inducers, this parameter seems to be important for enzyme activity, which depends also on the fungal strains.

Fabrication of solid-state nanopores and its perspectives.

Nanofluidics is becoming an extensively developing technique in the field of bioanalytical chemistry. Nanoscale hole embed in an insulating membrane is employed in a vast variety of sensing platforms and applications. Although, biological nanopores have several attractive characteristics, in this paper, we focused on the solid-state nanopores due to their advantages as high stability, possibility of diameter control, and ease of surface functionalizing. A detection method, based on the translocation of analyzed molecules through nanochannels under applied voltage bias and resistive pulse sensing, is well established. Nevertheless, it seems that the new detection methods like measuring of transverse electron tunneling using nanogap electrodes or optical detection can offer significant additional advantages. The aim of this review is not to cite all related articles, but highlight the steps, which in our opinion, meant important progresses in solid-state nanopore analysis.

Staphylococcus aureus and MRSA Growth and Biofilm Formation after Treatment with Antibiotics and SeNPs.

Methicillin-resistant Staphylococcus aureus (MRSA) is a dangerous pathogen resistant to ß-lactam antibiotics. Due to its resistance, it is difficult to manage the infections caused by this strain. We examined this issue in terms of observation of the growth properties and ability to form biofilms in sensitive S. aureus and MRSA after the application of antibiotics (ATBs)-ampicillin, oxacillin and penicillin-and complexes of selenium nanoparticles (SeNPs) with these ATBs. The results suggest the strong inhibition effect of SeNPs in complexes with conventional ATBs. Using the impedance method, a higher disruption of biofilms was observed after the application of ATB complexes with SeNPs compared to the group exposed to ATBs without SeNPs. The biofilm formation was intensely inhibited (up to 99%±7% for S. aureus and up to 94%±4% for MRSA) after application of SeNPs in comparison with bacteria without antibacterial compounds whereas ATBs without SeNPs inhibited S. aureus up to 79%±5% and MRSA up to 16%±2% only. The obtained results provide a basis for the use of SeNPs as a tool for the treatment of bacterial infections, which can be complicated because of increasing resistance of bacteria to conventional ATB drugs.

Correction: The Zinc-Schiff Base-Novicidin Complex as a Potential Prostate Cancer Therapy.

[This corrects the article DOI: 10.1371/journal.pone.0163983.].

A Review of Adsorbents for Heavy Metal Decontamination: Growing Approach to Wastewater Treatment.

Heavy metal is released from many industries into water. Before the industrial wastewater is discharged, the contamination level should be reduced to meet the recommended level as prescribed by the local laws of a country. They may be poisonous or cancerous in origin. Their presence does not only damage people, but also animals and vegetation because of their mobility, toxicity, and non-biodegradability into aquatic ecosystems. The review comprehensively discusses the progress made by various adsorbents such as natural materials, synthetic, agricultural, biopolymers, and commercial for extraction of the metal ions such as Ni2+, Cu2+, Pb2+, Cd2+, As2+ and Zn2+ along with their adsorption mechanisms. The adsorption isotherm indicates the relation between the amount adsorbed by the adsorbent and the concentration. The Freundlich isotherm explains the effective physical adsorption of the solute particle from the solution on the adsorbent and Langmuir isotherm gives an idea about the effect of various factors on the adsorption process. The adsorption kinetics data provide valuable insights into the reaction pathways, the mechanism of the sorption reaction, and solute uptake. The pseudo-first-order and pseudo-second-order models were applied to describe the sorption kinetics. The presented information can be used for the development of bio-based water treatment strategies.

Algal metabolites: An inevitable substitute for antibiotics.

Antibiotic resistance is rising at a pace that is difficult to cope with; circumvention of this issue requires fast and efficient alternatives to conventional antibiotics. Algae inhabit a wide span of ecosystems, which contributes to their ability to synthesize diverse classes of highly active biogenic metabolites. Here, for the first time, we reviewed all possible algal metabolites with broad spectra antibacterial activity against pathogenic bacteria, including antibiotic-resistant strains, and categorized different metabolites of both freshwater and marine algae, linking them on the basis of their target sites and mechanistic actions along with their probable nanoconjugates. Algae can be considered a boon for novel drug discovery in the era of antibiotic resistance, as various algal primary and secondary metabolites possess potential antibacterial properties. The diversity of these metabolites from indigenous sources provides a promising gateway enabling researchers and pharmaceutical companies to develop novel nontoxic, cost-effective and highly efficient antibacterial medicines.

Peptide-Carbon Quantum Dots conjugate, Derived from Human Retinoic Acid Receptor Responder Protein 2, against Antibiotic-Resistant Gram Positive and Gram Negative Pathogenic Bacteria.

Antibiotic-resistant bacterial infections have become global issues for public health, which increases the utter need to develop alternatives to antibiotics. Here, the HSER (Homo sapiens retinoic acid receptor) peptide was designed from retinoic acid receptor responder protein 2 of Homo sapiens, and was conjugated with synthesized CQDs (carbon quantum dots) for enhanced antibacterial activity in combination, as individually they are not highly effective. The HSER-CQDs were characterized using spectrophotometer, HPLC coupled with electrospray-ionization quadrupole time-of-flight mass spectrometer (ESI-qTOF) mass spectrometer, zeta potential, zeta size, and FTIR. Thereafter, the antibacterial activity against Vancomycin-Resistant Staphylococcus aureus (VRSA) and Escherichia coli (carbapenem resistant) was studied using growth curve analysis, further supported by microscopic images showing the presence of cell debris and dead bacterial cells. The antibacterial mechanism of HSER-CQDs was observed to be via cell wall disruption and also interaction with gDNA (genomic DNA). Finally, toxicity test against normal human epithelial cells showed no toxicity, confirmed by microscopic analysis. Thus, the HSER-CQDs conjugate, having high stability and low toxicity with prominent antibacterial activity, can be used as a potential antibacterial agent.

Characterization and in vitro Analysis of Probiotic-Derived Peptides Against Multi Drug Resistance Bacterial Infections.

An inexorable switch from antibiotics has become a major desideratum to overcome antibiotic resistance. Bacteriocin from Lactobacillus casei, a cardinal probiotic was used to design novel antibacterial peptides named as Probiotic Bacteriocin Derived and Modified (PBDM) peptides (PBDM1: YKWFAHLIKGLC and PBDM2: YKWFRHLIKKLC). The loop-shaped 3D structure of peptides was characterized in silico via molecular dynamics simulation as well as biophysically via spectroscopic methods. Thereafter, in vitro results against multidrug resistant bacterial strains and hospital samples demonstrated the strong antimicrobial activity of PBDM peptides. Further, in vivo studies with PBDM peptides showed downright recovery of balb/c mice from Vancomycin Resistant Staphylococcus aureus (VRSA) infection to its healthy condition. Thereafter, in vitro study with human epithelial cells showed no significant cytotoxic effects with high biocompatibility and good hemocompatibility. In conclusion, PBDM peptides displayed significant antibacterial activity against certain drug resistant bacteria which cause infections in human beings. Future analysis are required to unveil its mechanism of action in order to execute it as an alternative to antibiotics.

A Novel Biocompatible Titanium-Gadolinium Quantum Dot as a Bacterial Detecting Agent with High Antibacterial Activity.

: In this study, the titanium-gadolinium quantum dots (TGQDs) were novel, first of its type to be synthesized, and fully characterized to date. Multiple physical characterization includes scanning electron microscopy (SEM), scanning electrochemical microscope (SCEM), x-ray fluorescence, spectrophotometry, and dynamic light scattering were carried out. The obtained results confirmed appropriate size and shape distributions in addition to processing optical features with high quantum yield. The synthesized TGQD was used as a fluorescent dye for bacterial detection and imaging by fluorescent microscopy and spectrophotometry, where TGQD stained only bacterial cells, but not human cells. The significant antibacterial activities of the TGQDs were found against a highly pathogenic bacterium (Staphylococcus aureus) and its antibiotic resistant strains (vancomycin and methicillin resistant Staphylococcus aureus) using growth curve analysis and determination of minimum inhibitory concentration (MIC) analysis. Live/dead cell imaging assay using phase-contrast microscope was performed for further confirmation of the antibacterial activity. Cell wall disruption and release of cell content was observed to be the prime mode of action with the reduction of cellular oxygen demand (OD).

CdSe QD Biosynthesis in Yeast Using Tryptone-Enriched Media and Their Conjugation with a Peptide Hecate for Bacterial Detection and Killing.

The physical and chemical synthesis methods of quantum dots (QDs) are generally unfavorable for biological applications. To overcome this limitation, the development of a novel "green" route to produce highly-fluorescent CdSe QDs constitutes a promising substitute approach. In the present work, CdSe QDs were biosynthesized in yeast Saccharomyces cerevisiae using a novel method, where we showed for the first time that the concentration of tryptone highly affects the synthesis process. The optimum concentration of tryptone was found to be 25 g/L for the highest yield. Different methods were used to optimize the QD extraction from yeast, and the best method was found to be by denaturation at 80 °C along with an ultrasound needle. Multiple physical characterizations including transmission electron microscopy (TEM), dynamic light scattering (DLS), energy-dispersive X-ray spectroscopy (EDX), and spectrophotometry confirmed the optical features size and shape distribution of the QDs. We showed that the novel conjugate of the CdSe QDs and a cell-penetrating peptide (hecate) can detect bacterial cells very efficiently under a fluorescent microscope. The conjugate also showed strong antibacterial activity against vancomycin-resistant Staphylococcus aureus (VRSA), methicillin-resistant Staphylococcus aureus (MRSA), and Escherichia coli, which may help us to cope with the problem of rising antibiotic resistance.