Journal of Surface Science and Technology

Dielectric Relaxation Studies on the Hydration Dynamics of Ionic, Non-Ionic and Zwitterionic Surfactants in Aqueous Acetate Buffer Solution

R. Sampathkumar — 2023-02-15

Dielectric relaxation studies of acetate buffer solutions of Sodium Dodecyl Sulphate (SDS- anionic), Cetyl Trimethyl Ammonium Bromide (CTAB- cationic), Tween 80 (TW-80-non-ionic), Betaine Anhydrous (BA- zwitterionic) surfactants have been examined in the frequency region between 1GHz and 25GHz for various concentrations of surfactants at the temperatures of 283, 288, 293 and 298K using time domain dielectric spectroscopy. The obtained corrected loss spectra of all the amphiphiles except betaine anhydrous in acetate buffer solution depicted peaks near 1-2GHz and 15GHz, respectively. For betaine anhydrous, expected peak was not observed in the 1-2GHz frequency region. The peak ascertained near 15GHz, and another peak about 1-2GHz was accorded to free water relaxation and bound water reorientation of the surfactant micelles, and has acquired the reliance of temperature with concentration in detail. Single Debye and Cole-Cole function was employed to compute the relaxation times of free water and bound water, respectively. The Arrhenius plot was used to calculate the enthalpy and entropy for the micelle forming surfactants.

Recent Studies on the Drug Delivery of Nebulizers - A Review

N. Vinoth — 2023-02-15

This article provides a summary of some of the most current research on the delivery of drugs to the lungs, as well as a discussion of some of the limitations of these studies. Nebulizers have been in use for more than a century to deliver aerosolized drugs to patients suffering from respiratory disorders. Aerosol devices such as these are the best option for people who have trouble managing their inhalation. Because of the actuation required, pressurised Metered-Dose Inhalers (pMDI) and Dry Powder Inhalers (DPI) are unable to generate the necessary inspiratory flow required for successful aerosol drug delivery. Currently, we are looking into how the working mechanism of different nebulizers interacts with the physicochemical features of the formulations. We are looking into a wide range of devices, such as jet, ultrasonic, and vibrating-mesh nebulizers. In this study, the researchers hope to describe the many different types of nebulizers that are currently available on the market, evaluate their performance in aerosol drug delivery, and recommend treatment approaches for patients with chronic obstructive pulmonary disease.

Synthesis, Surface Active Properties and Antimicrobial Activity of Novel Ester – Amidoamine Linked Double Tailed Cationic Surfactants

Kumudini Aher — 2023-02-15

Three novel ester-amidoamine linked cationic surfactants bearing a double tail were synthesized. Their chemical structures were interpreted with FTIR, 1H and 13C NMR spectroscopy. These surfactants consist of hydrophobes that may be obtained from sustainable resources. The objective was to synthesize a double tailed amidoamine having two functional groups in the structure and to investigate the effect of these groups on the interfacial as well as physical properties of the surfactants. The interfacial properties of the surfactants were determined using tensiometry, conductometry measurements and dye solubilization techniques. The synthesized surfactants have been found to exhibit quite low CMC in comparison with conventional surfactants of similar structure. The effect of sodium chloride on their surface properties was also studied. They were found to possess good and stable foaming ability and wettability. All the synthesized surfactants delivered appreciable antimicrobial activity against three tested microorganisms, Staphylococcus aureus and Escherichia coli.

Self-Assembly Study of Sodium Salt of 2-Amidodecyl Pyridine-5-Boronic Acid and Sodium Salt of 2-Amidododecyl Pyridine-5-Boronic Acid in Buffer Solution

Sumita Roy — 2023-02-15

Boronic acid based amphiphiles are new generation green surfactant materials because they degrade to produce environmentally friendly boric acid. This study describes the interfacial property as well as aggregation behaviour of two pyridine based boronic acid amphiphiles containing amide linkage in hydrocarbon chain named sodium salt of 2-amidodecyl pyridine-5-boronic acid (SADPB) and sodium salt of 2-amidododecyl pyridine-5-boronic acid (SADDPB). Tensiometry study was executed for investigation of interfacial properties of pyiridine based boronic acid derivatives. Polarity and viscosity of the microenvironment of aggregates was investigated using fluorescence technique. DLS measurement suggested size of the assemblies of SADDPB is larger than SADPB in solutions. XRD technique was employed to examine arrangement of the hydrophobic tails in the bilayer aggregates. TEM technique was utilised to scrutinize aggregate morphology in solutions. The findings showed prospect of these amphiphiles to be applicable as drug carrier in pharmaceutical industries.

Mixed Micelle Properties of Anionic Dimeric Surfactants with Anionic, Cationic, and Nonionic Surfactants

Naveen Kumar — 2023-02-15

Herein, we have investigated the mixed micellar behavior of carboxylate anionic dimeric surfactants (CAD12 and CAD16) with commercial surfactants; anionic type i.e., sodium dodecyl sulfate, cationic i.e., cetyltrimethylammonium bromide and nonionic i.e., polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether. The CMC values of mixed surfactants obtained from conductivity data decrease with a mole fraction of dimeric surfactants. The micellar characteristics (ideal CMC) and mutual interaction parameters (β) have been computed with the aid of theoretical models proposed by Clint, and Rubingh. In addition to this, thermodynamic parameters of micellization like 0 ΔG⁰_mic, ΔH⁰_mic, and ΔS⁰_mic were evaluated and discussed.

Hierarchical Self-Assembly in DNA Ionogel: Effect of γ-Radiation on Gel Properties

Pankaj Kumar Pandey — 2023-02-15

DNA ionogels prepared by adding 1-ethyl-3-methylimidazolium chloride on low energy gamma irradiated DNA solution samples reveal non-trivial self-assembly. Variations in secondary structure and low-frequency gel rigidity modulus G₀ captured this unique hitherto unexplored features of these gels. Interestingly, at higher radiation dose (0 to 100 Gy) samples could partially lose their initial rigidity. Dynamic light scattering revels dose dependent relaxation dynamics corresponding to ergodicity breaking time. In particular, viscosity and rheology showed that the time of gelation t_gel, temperature of gelation T_gel and strength of gelation G₀ are gamma ray dose dependent. DNA Ionogel melting with temperature shows self-assembled characteristics of this biomaterial. Gelation kinetics of ionizing radiation treated DNA strands have been studied in literature.

Effect of Variation of pH and Shell Thickness upon the Optical and Structural Characteristics of PVA Capped CdSe and CdSe/ZnO Nanoparticles

Pallabi Boro — 2023-02-15

Poly-Vinyl Alcohol (PVA) capped Cadmium Selenide (CdSe) and Cadmium Selenide/Zinc Oxide (CdSe/ZnO) core/shell semiconductor/semiconductor nanoparticles have been synthesized using wet chemical precipitation method. The pH of each solution was varied ranging from 9.5 to 11.5. Particle size of the CdSe nanoparticles was estimated using Brus Equation. The results of UV-Visible spectroscopy of core CdSe samples show blue shifting of absorption edges in a range of 342-377 nm compared to that of the bulk CdSe 712 nm and red shifting of the absorption edges of the core /shell samples in a range (346-357) nm in comparison to the core sample, over which the shell is deposited. For CdSe core nanoparticles, the band gap values were found to be in the range of 3.70–3.90 eV, which is larger than the bulk CdSe of 1.74 eV. Also the band gap values for the core/shell nanoparticles were in the range of 3.75-3.80 eV. The positions of excitonic emission peak obtained from photoluminescence spectra for the core is around 323 nm and for the core/shell samples is around 324nm. The average crystallite size of the core/shell CdSe/ZnO sample was obtained from XRD spectra in the range of 62-69 nm and for the core CdSe sample it was of 11-31 nm. The core and the core/shell samples were more or less spherical as obtained from the SEM analysis. Some of the core nanoparticles were 3-8 nm in size whereas the core/shell nanoparticles were 20-50 nm in size as obtained from HRTEM analysis.

Ecofriendly Synthesis and Characterization of Magnesium based Metal - Organic Frame Work

O. Lekshmy — 2023-02-15

Magnesium based metal - organic Framework (MOF) was synthesized by using Benzene Di-Carboxylic acid (BDC), MgSO₄.7H₂O and a flower extract of Clitoria ternatea. The prepared MOF was characterized by FTIR spectrum, SEM-EDS, XRD, DLS and PL Spectrum. The crystalline nature of the synthesized MOF was revealed in XRD patterns. The nano particle nature of the MOF was confirmed from the SEM pictures. FT-IR spectra showed a peak at 520cm^-1 designated characteristic absorption bands of synthesized Mg-MOF nano particles. The zeta potential value showed that the surface charge of the synthesized MOF is neutral and hence disperse in solution without having any tendency for agglomeration and coagulation on standing. The photoluminescence spectra indicated luminescent nature and hence this nano crystalline MOF finds very good application as luminescent material and as sensing material.

Dilution Driven Self-assembly and Re-entrant Phase Transition in Molecular Hydrogels

Rahul Ranjan — 2023-02-15

TX-100 molecular hydrogels exhibited re-entrant melt-gel-sol phase transition driven solely by dilution, which sequentially altered the self-assembly of the micellar formations and their population was investigated through the monitoring of the physical parameters namely, solution viscosity, particle size histogram, ergodicity, and gel rigidity modulus. This phenomenon was noticed at 20°C in the TX-100 concentration region of 0.2 to 1.2 M much above the critical micellar concentration of 0.22 mM. The particle size histograms revealed the presence of spherical micelles (size »3 nm) in the solution ([TX-100] < 0.5 M) which formed entangled wormlike cylindrical micelles (apparent hydrodynamic radius » 50 nm) when (0.5 M< [TX-100] < 0.9 M) giving rise to a gel-like structure. Further increase in the TX-100 concentration increased the propensity of these wormlike cylindrical micelles that got randomly distributed creating a dense melt phase. Interestingly, we observed transition solely driven by dilution which defined complete re-entrant behavior at room temperature. These molecular gels could be created by dilution of the melt or concentration of the sol unlike in the polymer gels. Remarkably, this hitherto little known unique phenomenon was exhibited by a simple system of non-ionic surfactant solution. Thus, we have a hydration reversible gel at our disposal which has a special place in soft matter arena.