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  • Open access
  • 8149 Reads
Development of Metal Nanoparticle Based Sensing Platform for Lead in Aqueous Samples

Lead (Pb) is one of the highly persistent and major toxic health hazard listed by various health organizations. A stable, specific, and simple sensor which can rapidly detect the Pb in drinking water is required urgently. To this end, we have prepared stable and uniformly sized colloidal silver nanoparticles (AgNPs) using citric acid for the color-based sensing of Pb in water samples. The synthesized AgNPs are characterized by UV-Vis spectroscopy, DLS-Zeta, and TEM to access their optical and morphological properties. The cit-AgNPs have shown a great affinity/selectivity towards lead (Pb) over Cd, Mn, Cr, Fe, Co, Pb, Hg, Zn, and Ti ions. Thus, based on the interaction of cit-AgNPs and Pb, a colorimetric sensor for selective, specific, and expeditious detection of lead metal ions has been developed.

  • Open access
  • 50 Reads
Synthesis of nanosized powders for lead-acid battery pastes by recycling of used batteries
Published: 11 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

In the present work we have investigated the oxysulfate fraction of spent lead-acid battery pastes in search of an optimal method for its recycling. For this purpose, desulfurization and leaching were performed in one step by adding simultaneously sodium citrate and citric acid at varying temperatures (25-100оС) and heat treatment times (1-2h) in order to obtain a lead-citrate precursor for direct application in the production of lead oxide powder. Two types of lead citrate were obtained, (Pb(C6H5O7)2.H2O and Pb3(C6H5O7)2.3H2O). After calcination at low temperature (300oC), these precursors form a nanosized lead oxide powder. X-ray diffraction analysis (XRD) was performed at each stage of the study to monitor the changes in phase composition and crystallite size of the synthesized powder. Morphological features were investigated by scanning electron microscopy (SEM). An additional differential thermal analysis (DTA) was performed to determine the type of the obtained lead citrate. Finely dispersed lead oxide powders are formed. The measured crystallite sizes of the two main phases are: β-PbO(111) – 30-50nm and Pb(111) – 40 - 60nm, respectively.

  • Open access
  • 51 Reads
Nanoplatforms based on plasmonic nanoparticles for multitherapy in the treatment of cancer
Published: 11 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

In most of the cases, the diagnostic and therapy stages are carried out independently and this lead to
delays in the application of the treatments and, therefore, an important risk to the patients´ health. To
overcome these incoveniences, in the few last years theranostic has reached an important role to join
in a unique nanoplatform therapeutic treatment, action and monitoring of the response to simultaneous
therapy. Thus, we designed an hybrid nanosystems based on gold nanoparticles capable of
simultaneously combining their potential as a photodynamic therapeutic agent (PDT), plasmonic
photothermal therapy (PPTT) and/or chemotherapy to kill malignant cells. In order to do that,
gold nanorods (GNR) were functionalized by the layer-by-layer (LbL) assembly technique using
alternate layers of polyelectrolytes (PE): poly (styrene sulfonate) (PSS) and poly-L-lysine (PLL) as
anionically and cationically charged polymeric layers, and an outer layer of hyaluronic acid (HA) to
provide the hybrid particles with sufficient colloidal stability and steering ability. Doxorrubicin
(DOXO) and SiRNA were added by electrostatic interactions to the PSS and PLL layers for providing
chemo- and genetic therapy, respectively, controlling the % weight and encapsulated efficiency of
doxorubicin and SiRNA with their calibration curve. To provide the PDT capabilities to the
nanoplatform, the green indocyanine photosensitizer (ICG) was previously conjugated to the PLL
polymer and assembled into the nanoplatform by electrostatic interactions, checking its efficiency
with the fluorometer. In this way, hybrid particles formed by GNR coated with PSS/DOXO/PLL @
ICG@SiRNA / HA layers were obtained, in which the therapeutic PDT activity of the dye ICG,
chemo- activity of DOXO and the photothermal properties of the plasmonic metal nanoparticles can
be simultaneously be applied for efficient cancer therapeutics. Nanoplatforms were characterizated by
UV-Vis, FTIR and RAMAN spectroscopy, -potential and TEM. In addition, PPTT therapy of the
nanoplatforms was evaluated at different irradiation powers. Finally, single oxygen ( 1 O 2 ) production
under NIR light excitation by the hybrid nanosystem was evaluated in vitro at several power
intensities by means of fluorescence and absorbance spectroscopies and fluorescent microscopy.

  • Open access
  • 46 Reads
Enzymatic deposition of pseudo-polydopamine thin films: a mild, versatile and low-waste mussel-inspired coating technology

The mimicry of the underwater mussel adhesion strategy for the development of innovative and versatile dip-coating technologies is exemplified by the introduction of polydopamine (PDA) as a highly adhesive biomaterial for surface functionalization and coating, incorporating the key catechol and amine functionalities of byssal proteins and produced by the oxidative polymerization of dopamine under alkaline conditions.1 Despite unabated interest and an ever expanding use for various surface functionalization applications, PDA-based technologies suffer from some limitations that have prompted intense studies toward novel mussel-inspired surface chemistry.2 They are related to: a) the intrinsic toxicity of the precursor dopamine; b) the use of an alkaline pH; c) the need for high dopamine concentrations (10 mM), and d) difficulties to control film thickness and properties due to the slow kinetics of autoxidation.3 A possible means of bypassing limitations inherent to the autoxidation protocol relies on use of enzymes like tyrosinase, which can be exploited to modulate catecholamine oxidation at pH values around neutrality, and were thus proposed as a practical and convenient ways of obtaining nanometer-thick and uniform films with diverse functionalities.4,5

Herein, we report the tyrosinase-catalyzed polymerization of tyramine as a mild, versatile and efficient procedure for the development of adhesive PDA-type films (ψ-PDA) that could be obtained at neutral pH (i.e. 6.8) and at much lower substrate concentration (e.g. 1 mM) compared to the standard autoxidative PDA coating protocol (typically 10 mM of dopamine).6 ψ-PDA films display structural and physicochemical properties similar to those of PDA films and similar, or even better, antioxidant activity. Finally, the possibility of using tyramine together with confined tyrosinase to achieve site-specific polymerization and/or film deposition is assessed against dopamine. The rationale of the experiments is to prevent the uncontrolled autoxidative deposition of black precipitate, a major drawback of PDA coating technology which may interfere with specific applications. ψ-PDA deposition by tyrosinase-catalyzed tyramine oxidation is thus proposed as a controllable and low-waste technology for selective surface functionalization and coating or for clean eumelanin particle production.


[1] Ryu J.H.; Messersnith P.B.; Lee H. ACS Appl. Mater. Interfaces, 2018, 10, 7523-7540.

[2] Lee B.P.; Messersmith P.B.; Israelachvili J.N.; Waite J.H. Annu. Rev. Mater. Res., 41 (2011), 99-132.

[3] Ball V.; Del Frari D.; Toniazzo V.; Runch D. J. Colloid Interface Sci., 386 (2012), 366-372.

[4] Kim J. Y.; Kim, W.I.; Youn W.; Seo J.; Kim B.J.; Lee J.K.; Choi I.S. Nanoscale, 10 (2018), 13351-13355.

[5] Zhong Q.Z.; Richardson J.J.; Li S.; Zhang W.; Ju Y.; Li J.; Pan S.; Chen J.; Caruso F. Angew. Chem. Int. Ed.2019 10.1002/anie.201913509.

[6] Alfieri M.L.; Panzella L.; Youri A.; Napolitano A.; Ball V.; d’Ischia M. Int. J. Mol. Sci. 2020, 21, 4873.

  • Open access
  • 79 Reads
Photoactive carbogenic nanotracers with remarkable antimicrobial properties for pH-sensing applications
Published: 11 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

Carbogenic nanoparticles (also known as C-dots) constitute a new class of carbon-based materials, which are easily synthesized via thermal treatments of carbon-rich precursors. These spherical nanoemitters are composed of an amorphous core with an approximate size of below 10 nm and exhibit exquisite biocompatibility, simplicity of surface modification, excellent chemical stability and broad excitation spectra. Their exceptional photoluminescent properties are related to the dual emissive mode with the excitation-wavelength independent or dependent emission, attributed to the presence of organic fluorophores or carbogenic cores, respectively.
To date, several nanomaterials have been developed to measure the intercellular pH, including fluorescent proteins, organic dyes or quantum dots. Among them, C-dots are characterized by resistance to photobleaching, good permeability and lack of toxic metal components in their structure. Moreover, these nanoemitters demonstrate excellent analytical performance in detecting heavy metals, drugs, biological molecules, poisonous reactants or explosives, thus can be applied as highly selective optical nanoprobes. In summary, our results demonstrate the potential to utilize biocompatible carbogenic nanotracers for an early-stage disease diagnosis as well as highlight their remarkable antimicrobial activity against Escherichia coli and Staphylococcus aureus.

  • Open access
  • 150 Reads
Development of polymeric micelles for in vivo mRNA delivery through stable complexation with flexible block catiomers

   Messenger RNA (mRNA) has high potential for developing a wide range of therapeutics, though effective delivery systems are still required for its broad application. Polymeric micelles loading mRNA via polyion complexation with block catiomers are emerging as promising carriers for mRNA delivery. However, the in vivo stability of polyion complexes (PIC) has been limited so far, demanding for stabilization strategies. Controlling the stiffness of the cationic segment in the catiomers could promote PIC formation and micelle stability. Nevertheless, the impact of polycation flexibility on the function of mRNA-loaded PIC micelles (mRNA/m) remains unknown. Herein, we studied the effect of the stiffness of the polycation segment of catiomers on the association and performance of mRNA/m toward enhancing stability and delivery efficiency. Thus, a block catiomer system having polycation segments with different flexibility, i.e. poly(ethylene glycol)-poly(glycidylbutylamine) (PEG-PGBA) and PEG-poly(L-lysine) (PEG-PLL), was developed and used to prepare mRNA/m. The flexible PEG-PGBA catiomer allowed 100-fold stronger binding to mRNA than PEG-PLL, resulting in mRNA/m with enhanced mRNA protection against enzymatic attack and resistance to dissociation from polyanions. mRNA/m from PEG-PGBA significantly increased translation efficiency both in vitro and in vivo, and enhanced mRNA bioavailability in blood after intravenous injection. These results indicate the importance of polycation flexibility for developing stable PIC with mRNA directed to enhance delivery.

  • Open access
  • 60 Reads
Electrospray ion beam deposition of complex molecules on surfaces in the vacuum
Published: 11 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

This paper aims to develop the vacuum electrospray deposition technique, which represents a gradual change in the range of scientific research through comparing between electrospray ion beam deposition and conventional deposition techniques. The electrospray deposition instrument is considered a simple method and has several advantages. Moreover, this paper presented an electrospray deposition source designed with and without mass selection used. A new phase which is called the deflection chamber stage has been added to the electrospray deposition source which is very similar to other electrospray deposition sources of the commercially available UHV-4 system from Molecularspray Ltd. This stage plays an important role by bending the ion beam in order to work towards separating two components of the beam. Just a few groups worldwide follow this method since the scale and price of the present mass-selected electrospray deposition systems are not permitted in designing an instrument that can be installed in several research laboratories. The number of molecules was deposited using this technique such as fluorescein, ferrocene, and a mixture of fluorescein and ferrocene. As well as, I included some data for spraying different solutions by presenting four experiments that have collected using the electrostatic ion deflection from spraying fluorescien (water + methanol 50:50), fluorescien dissolved in methanol, ferrocene dissolved in methanol, and a mixture of ferrocene and fluorescein dissolved in methanol. In my future work, I have planned to conduct SIMION software to model the system in an ion workbench scenario to simulate the energies and masses of the molecular ions through the system in order to refine the mass-selection process.

  • Open access
  • 95 Reads
Development and in vitro characterization of diacerein loaded chitosan-chondroitin sulfate nanoemulgel for osteoarthritis
Published: 11 November 2020 by MDPI in 2nd International Online-Conference on Nanomaterials session Poster

The proficient function of diacerein and anti-inflammatory polymers have been utilized to develop sustained release transdermal diacerein nanoemulgel for long term osteoarthritis treatment, by overcoming the deleterious outcomes of drug associated with the oral route. Chitosan (CHS) and Chondroitin Sulfate (CS) were employed as natural anti-inflammatory and biodegradable polymers to formulate diacerein nanoparticles (DCR-NPs) through ionic gelation method. Optimized nano-formulation was prepared using Design Expert software, by investigating the impact of polymers and surfactant concentrations on particle size, PDI and entrapment efficiency employing Response Surface Methodology (RSM). DCR-NPs formulated using 0.4% CHS, 0.1% CS and 0.015% (w/v) Tween 80 depicted spherical shaped nanoparticles with particle size of 320.0 ± 3 nm having PDI, zeta potential and entrapment efficiency of 0.3 ± 0.07, 40 ± 0.3 mV and 82 ± 4.16% respectively. DCR-NPs were further analyzed for confirmation of electrostatic interactions between polymers and drug through Fourier transform-infrared spectroscopy (FTIR). Through in vitro studies 95% release of DCR in 72 h was exhibited following Korsmeyer-Peppas model. For transdermal application, nanoemulgel of optimized DCR-NPs was formulated utilizing argan oil as permeation enhancer with intrinsic anti-inflammatory properties, providing synergistic effect to the formulation. Nanoemulgel was characterized in terms of visual appearance, spreadability, drug content and rheological behavior providing sustained release of drug up to 96 h following Higuchi model with improved ex vivo permeation, confirmed by fluorescent microscopy. Concisely, DCR-nanoemulgel sustained the release of drug having superior penetration properties with provision of enhanced therapeutic effect owing to the presence of CHS, CS and argan oil possessing indelible anti-inflammatory attributes.

  • Open access
  • 80 Reads
A novel one-step green method to synthesis of palladium nanoparticles

Palladium nanoparticles (PdNPs) are one of the most attractive metal nanomaterials because of their excellent physicochemical properties. PdNPs have been studied for many different applications such as Suzuki cross-coupling reactions, hydrogen purification/storage/sensing, CO oxidation, fuel cells, prodrug activation, and antimicrobial therapy. Recently, PdNPs have been explored as photo-absorbers for photothermal therapy and photoacoustic imaging in the treatment of cancer disease. Herein, we reported a scalable, efficient, green, and one-step method to synthesis PdNPs. The chitosan polymer was used as a stabilizer and vitamin C was used as a reducing agent. Interestingly, the reaction temperature can be adjusted to the size of PdNPs. When the reaction temperature was increased from 25oC to 95oC, the morphology of resulted PdNPs changed from flower shape to spherical shape and their nanoparticles sizes decreased from 64 nm to 29 nm. The characterization revealed that the obtained PdNPs were relatively uniform in size, shape and stable in aqueous solution.

  • Open access
  • 59 Reads
Gating mechanism of Hv1 studied by molecular dynamic simulations

The voltage-gated proton channel (Hv1) plays the important role in proton extrusion, pH homeostasis, sperm motility, and cancer progression. The closed-state structure of Hv1 was revealed by the X-ray crystallography. However, the opened-state structure has not been captured yet. To investigate the mechanism of proton transfer in Hv1, molecular dynamics simulations were performed with the closed-state structure of Hv1 under electric field and pH conditions. The residues arrangement on the closed-state structure revealed that the selectivity filter (Asp108) which is located in the hydrophobic layer (consists of two Phe residues 146 and 179) might prevent water penetration. In molecular dynamics simulations, we observed that the channel opened by moving up of 3 Arg on the S4 helix and a continuous hydrogen-bonded chain of water molecules (a “water wire”) went through the channel when it opened. During simulations, the open channel allowed water molecules to pass through the channel but excluded other ions. This indicates Hv1 channel is highly selective for protons. Our results clearly showed the Hv1 channel are voltage-and pH-gradient sensing.