Spectroscopy Methods Research Articles

SYNTHESIS AND OPTICAL PROPERTIES OF POLYCRYSTALLINE Sb2S3 AND (Sb2S3)90Ag10

Recently, much research has been devoted to finding new or improving existing photovoltaic materials. P-metal chalcogenides are attracting increasing attention due to their unique properties, including high photon absorption coefficient, significant dipole moment, optimal band gap and the ability to form solid solutions. To optimize the electrical parameters (band gap, concentration of charge carriers) in order to improve the performance of solar cells, the formation of doped compounds is used. In the present work, the synthesis and study of silver-doped polycrystalline Sb2S3 was carried out. The obtained alloys were characterized by X-ray diffraction and diffuse reflectance spectroscopy. The phase composition of the synthesized alloys was determined by X-ray diffraction method. The powder patterns of the (Sb2S3)90Ag10 alloy contains two systems of reflexes: those corresponding to the Sb2S3 and ternary AgSbS2 phases. The optical parameters of the synthesized materials were studied by diffuse reflectance spectroscopy method. The diffuse reflectance spectra were analyzed using the Kubelka-Munk function. The pseudogap was determined using the Tauc method.

MALDI-TOF Mass Spectrometry as the Tool for the Identification of Features of Polymers Obtained by Inverse Vulcanization

The MALDI-TOF mass-spectrometry was employed to analyze the structure of the reaction products of limonene, a natural terpene, and elemental sulfur, with the objective of identifying the occurrence of side processes, such as oxidative dehydrogenation, aromatization, and the Diels–Alder reaction cascade. The MALDI-TOF mass-spectrometry was demonstrated to be effective for the analysis of high-sulfur polymers obtained by the inverse vulcanization reaction, allowing for the unambiguous separation of sulfur-containing and hydrocarbon molecular fragments and the detailed characterization of macromolecular structures. By varying the ratio of sulfur (S8) and limonene in the initial reaction system, we were able to ascertain the limiting amount of sulfur that can be covalently bonded by terpene, as well as determine the average length of polysulfide chains under the assumption of equal reactivity and complete depletion of all double bonds. The side reaction of limonene aromatization, as indicated by the MALDI-TOF spectrum of the product resulting from its interaction with elemental sulfur, was corroborated by 1H and 13C NMR spectroscopy. Consequently, the registration and interpretation of MALDI-TOF spectra of inverse vulcanization products, either independently or in conjunction with the application of 1H and 13C NMR spectroscopy methods, as well as the determination of the limiting number of sulfur atoms that can be bound to one molecule of an unsaturated compound, paves the way for new avenues of investigation into the structure and side reactions involved in the synthesis of high-sulfur polymers.

A rapid and high-throughput fraud detection method of Philippine coconut wine (lambanog) using 1H qNMR spectroscopy

Methanol contamination of the Philippine coconut spirit lambanog (often called coconut wine) is the major cause of lambanog-related deaths in the country. Hence, a strict quality control and detection method must be established for methanol in tandem with ethanol analysis. In this study, a quantitative Nuclear Magnetic Resonance spectroscopy (qNMR) method using 1H analysis was developed to quantify the methanol and ethanol in 26 lambanog samples collected from four different provinces in Luzon, Philippines. A certified qNMR standard was used as an internal standard for the 1H NMR analyses to increase the accuracy of the measurements. The calculated limit of detection and limit of quantification of methanol with values of 0.076%(v/v) and 0.25%(v/v), respectively, were sufficiently low and allow the monitoring of methanol within the acceptable safety level. Moreover, the results of methanol and ethanol analysis using the proposed method were in good agreement with those obtained from GC-FID analysis which is the conventional method for alcohol analysis. In contrast to GC-FID, the qNMR method for simultaneous alcohol analysis can provide results in a shorter period. The results of this study show the potential of the qNMR method to be used as an alternative analytical method which widens the range of analytical possibilities to detect methanol in lambanog samples for the safety of the consumers.

Corrosion inhibition effects of celery (Apium graveolens) seeds extract on carbon steel in acid medium

The present study highlights the inhibition performance of celery seeds (CS) extract on carbon steel immersed in 1M HCl, using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. This extract is selected due to biodegradable, renewable, and foremost aspect, is safe towards both the human being and environment. The studied inhibitor was easily extracted by using a simple aqueous extraction procedure. The experimental results show that the investigated inhibitor can effectively retard the corrosion process that occurs to carbon steel in hydrochloric acid solution. Electrochemical impedance spectroscopy (EIS) spectra showed that inhibition efficiency increases with the increasing of (CS) extract concentration. Among the studied inhibitor showed maximum inhibition efficiency of 96,86% at 250 ppm. Polarization curves indicate that (CS) extract acted as mixed type of inhibitors with a predominant effect on the anodic reactions. Basic calculations for the adsorption studies were also carried out. The adsorption of the extract onto carbon steel surface followed the Langmuir adsorption isotherm.

Biochemical components of corneal stroma: a study on myopia classification based on Raman spectroscopy and deep learning methods

The study aimed to identify differences in the biochemical composition of corneal stroma lenses across varying degrees of myopia using Raman spectrum characteristics. Corneal stroma lens samples from 38 patients who underwent small incision lens extraction (SMILE) surgery, were categorized into low (n = 9, spherical power ≧ -3.00D), moderate (n = 23, spherical power < -3.00D and > -6.00D), and high myopia (n = 6, spherical power ≦-6.00D) groups. A custom-built microscopic confocal Raman system (MCRS) was used to collect Raman spectra, which were processed by smoothing, denoising, and baseline calibrating to refine raw data. Independent sample t-tests were used to analyze spectral feature peaks among sample types. Significant differences (P < 0.001) were found in multiple Raman spectral characteristic peaks (854 cm-1, 937 cm-1, 1002 cm-1, 1243 cm-1, 1448 cm-1, and 2940 cm-1) between low and high myopia samples, particularly at 2940 cm-1. Differences were also found between low and moderate, and moderate and high myopia samples, although fewer than between low and high myopia samples. The three-classification model, particularly with PLS-KNN training, exhibited superior discriminative performance with accuracy rates of 95%. Similarly, the two-classification model for low and high myopia achieved high accuracy with PLS-KNN (94.4%) compared to PCA-KNN (93.3%). PLS dimensionality reduction slightly outperformed PCA, enhancing classification accuracy. In addition, in both reduction methods, the KNN algorithm demonstrated the highest accuracy and performance. The optimal PLS-KNN classification model showed AUC values of 0.99, 0.98, and 1.00 for ROC curves corresponding to low, moderate, and high myopia, respectively. Classification accuracy rates were 89.7% and 96.9%, and 100% for low and high myopia, respectively. For the two-classification model, accuracy reached 94.4% with an AUC of 0.98, indicating strong performance in distinguishing between high and low myopic corneal stroma. We found significant biochemical differences such as collagen, lipids, and nucleic acids in corneal stroma lenses across varying degrees of myopia, suggesting that Raman spectroscopy holds substantial potential in elucidating the pathogenesis of myopia.

Research of energy structure of crystalline compounds in Ag(Tl)-As(Р)-S(Se) systems

The paper presents the results of studying the peculiarities of formation of the valence band and the conduction band of crystalline compounds in Ag(Tl)-As(P)-S(Se) systems with sp3-type bond by using the photoelectron spectroscopy method. From the spectral distribution of photoemission by energy, the crystal photoelectron work function hν0 was determined. It was shown that the use of a limited basis (only ionization potentials of atoms and interatomic distances) for crystals with sp3-type bond within the framework of the LCAO model gives sufficiently accurate results of the position of the valence band top and the electron affinity value. Calculations show that the position of the valence band top defines the bonds of As-S(Se) and P-S(Se) atoms, while the hybridized orbitals of Ag and Tl atoms are formed in the conduction band.

Relationship between the octane number and the chemical composition of gasoline: study by FTIR spectroscopy

The oil refining process undergoes various heat treatments, during which several cuts are obtained, including cuts of gasoline of different chemical composition. Determination of physicochemical properties is essential for our fuel classification. In the present study and by exploiting a rarely used spectroscopic method in the field of production and characterization of fuels, FTIR Fourier transform infrared spectroscopy (a method characterized by its reliability and speed), we identified a correlation between the molecular composition of the fuel (translated by chemical number) and its octane number NO (a quite important parameter for species classification). The results of AR1 aromaticity index show a strong linear relationship between the latter and its NO octane number. In addition, NO also occurs in many modes depending on two indicators DOC (degree of condensation) and AR1. Indeed, the ACL aliphatic chain length index varies depending on the quality of the fuel and precisely on the subsequent fuel production process. Furthermore, this method illustrates the molecular composition of the fuel, the correlation determined between the chemical indices and the octane number offering the possibility of predicting this physico-chemical parameter.

Characterization of Physical and Chemical Properties of Multi-Source Metallurgical Dust and Analysis of Resource Utilization Pathways

Steel metallurgical dust, characterized by a substantial output, minute particle size, and intricate composition, poses a considerable risk of environmental contamination while simultaneously embodying an exceptionally high potential for recycling. To achieve its resource utilization, chemical analysis, particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, and water leaching methods were employed to investigate the chemical compositions, particle size distributions, phase compositions, and microscopic morphologies of blast furnace bag dust, sintering dust, converter fine dust, and electric arc furnace dust from steel plants. The results indicate that the four types of dust have extremely fine particle sizes, with the main distribution range of particle size being less than 100 μm. The main constituent element is Fe (19–56%), and it also contains Zn (1.4–33.5%), Pb, K, C, and other valuable elements. Alkali metals in blast furnace bag dust and sintering machine head dust existed mainly in the form of chloride. The zinc phases in sintering machine head dust and converter fine dust were ZnFe2O4, and the zinc phases in blast furnace bag dust were ZnCl2 and ZnFe2O4. Zinc in electric furnace dust was composed of ZnO and ZnFe2O4, accounting for 70.31% and 23.12%, respectively. There are significant differences in the types and contents of valuable elements among various dusts, making it difficult to achieve full-scale recovery through a single process. In view of this, a process of “in-plant recycling of harmless dusts—collaborative treatment of harmful dusts” has been proposed. Based on the characteristics of metallurgical dusts, multiple processes are used for collaborative treatment (using hydrometallurgical and pyrometallurgical methods), which can not only directly recover iron resources from dusts within the plant, but also avoid the waste of valuable elements such as Zn, Pb, K, Na, etc. It is hoped that the above work can provide a reference for steel enterprises to achieve full-scale and high value-added treatment of metallurgical dusts.

Evaluation of 1064 nm Raman for meat and bone meal species discrimination: From raw form to chemical and physical components

The 1064 nm Raman spectroscopy technique was employed to characterize raw, bone fragments (BF), meat fragments (MF), lipid, and residue of meat and bone meal (MBM) samples. Employing three chemometric algorithms, species discrimination models were optimized for the aforementioned sample types, indicating that the presence of BF favored discriminant analysis for poultry samples, yielding a classification error of 0.000. The species discrimination model constructed using Raman spectra combined with PLS-DA algorithm for residue samples was found to be overall optimal, with classification error for four species samples all below 0.061. A detailed analysis of the BF related spectral variables contributing significantly to PLS-DA discriminant analysis was conducted. Finally, this study established the complementarity of Raman spectroscopy in species discrimination analysis from both a physical and chemical components perspective, laying the theoretical groundwork for the development of a high-precision 1064 nm Raman spectroscopic analysis method for MBM species discrimination.

Crystal structure and magnetic properties of Fe doped BaTiO3 at morphotropic phase boundary

Ceramic compounds BaTi1-xFexO with x = 0 – 0.2 prepared by solid state reaction technique were studied using X-ray diffraction, Raman spectroscopy, and magnetometry methods focusing on the correlation between the structure and magnetic properties. Chemical doping with Fe ions leads to a concentration driven structural transformation from the single phase tetragonal (T-) structure to the hexagonal (H-) structure with a mixed structural state stable in the concentration range 0.06 <x ≤ 0.2. Increase in the Fe ions content causes a stabilization of weak ferromagnetic state driven by the exchange interactions Fe3+ – O – Fe3+ ions strongly dependent on the structural positions of the Fe ions. Increase of the dopant content above x = 0.08 leads to a decrease of the remnant magnetization which is mainly caused by a stabilization of Fe4+ ions as well as by the lattice defects associated with oxygen vacancies formed to keep electroneutrality of the compounds. The results of the structural and magnetization measurements allowed to itemize the type of exchange interactions between Fe ions residing different structural positions of the hexagonal lattice as well as to reveal structural instability of the T- and H- phases under ambient conditions and applied electric field which shows a possibility to control the structure and magnetic properties of the mixed compounds via external stimuli.

In-silico based Designing of benzo[d]thiazol-2-amine Derivatives as Analgesic and Anti-inflammatory Agents.

Benzo[d]thiazoles represent a significant class of heterocyclic compounds renowned for their diverse pharmacological activities, including analgesic and antiinflammatory properties. This molecular scaffold holds substantial interest among medicinal chemists owing to its structural versatility and therapeutic potential. Incorporating the benzo[d]thiazole moiety into drug molecules has been extensively investigated as a strategy to craft novel therapeutics with heightened efficacy and minimized adverse effects. The aim of the present research work was to design, synthesize and characterize the new benzo[d]thiazol-2-amine derivatives as potent analgesic and anti-inflammatory agents. The synthesis of the presented benzo[d]thiazol-2-amine derivatives was performed by condensing-(4-chlorobenzylidene) benzo[d]thiazol-2-amine with a number of substituted phenols in the presence of potassium iodide and anhydrous potassium carbonate in dry acetone. IR spectroscopy, 1HNMR spectroscopy, 13CNMR spectroscopy and Mass spectroscopy methods were used to characterize the structural properties of all 13 newly synthesized derivatives. The molecular properties of these newly synthesized derivatives were estimated to study the attributes of drug-like candidates. Benzo[d]thiazol-2-amine derivatives were molecularly docked with selective enzymes COX-1 and COX-2. Analgesic and anti-inflammatory activities of synthesized compounds were evaluated by using albino rats. Findings of the research suggested that compounds G3, G4, G6, G8 and G11 possess higher binding affinity than diclofenac sodium, when docking was performed with enzyme COX-1. Compounds G1, G3, G6, G8 and G10 showed lower binding affinity than Indomethacin when docking was performed with enzyme COX-2. In vitro evaluation of the COX-1 and COX-2 enzyme inhibitory activities was performed for synthesized compounds. Compounds G10 and G11 exhibited significant COX-1 and COX-2 enzyme inhibitory action with an IC50 value of 5.0 and 10 μM, respectively. Using the hot plate method and the carrageenan-induced rat paw edema model, the synthesized compounds were screened for their biological activities, including analgesic and anti-inflammatory activities. Highest analgesic action was exhibited by derivative G11 and the compound G10 showed the highest anti-inflammatory response. Inhibition of COX may be considered as a mechanism of action of these compounds. It was concluded that synthesized derivatives G10 and G11 exhibited significant analgesic and anti-inflammatory effect; therefore, the said compounds may be subjected to further clinical investigation for establishing these as future compounds for the treatment of pain and inflammation.

Study of the applicability of ACdSe (A – Co, Ni) thin films as catalysts for heavy metal capture

Expansion of the possibilities of using photoactive thin films with a unique combination of optical and morphological characteristics as a basis for creation of highly efficient catalysts for the aqueous media purification is one of the promising research areas in modern materials science, which has both fundamental significance and potential for practical application. This study examines the prospects for using modified thin CdSe films by substituting nickel or cobalt for cadmium and selenium as a basis for creating highly efficient catalysts for the aqueous media purification from heavy metals such as arsenic, manganese and iron. A rather inexpensive electrochemical synthesis method was proposed as a method for obtaining thin films, in which the substitution effect is achieved by addition of nickel or cobalt sulfates to the electrolyte, which allows obtaining films with an equally probable distribution of elements in the composition of the synthesized films. Optical spectroscopy methods were used as methods for characterization of the initial samples, which made it possible to establish the dependences of the change in the band gap and absorption bands on the composition of the synthesized films, as well as to anticipate the influence of morphological features on optical absorption. During the conducted studies it was established that partial substitution of nickel and cobalt for cadmium and selenium in the composition of films results in growth in the adsorption efficiency of heavy metals, alongside operation stability maintenance of modified films during cyclic tests. At the same time, enhancement of the adsorption efficiency of heavy metals for modified films is due to both an alteration in the optical properties of the films and morphological features associated with the specific surface area growth due to a reduction in the grain size and a more developed surface.

The GAPS programme at TNG

Ultra-hot Jupiters (UHJs) are gas giant planets orbiting close to their host star, with equilibrium temperatures exceeding 2000 K, and among the most studied planets in terms of their atmospheric composition. Thanks to a new generation of ultra-stable high-resolution spectrographs, it is possible to detect the signal from the individual lines of the species in the exoplanetary atmospheres. We employed two techniques in this study. First, we used transmission spectroscopy, which involved examining the spectra around single lines of Fe II. Then we carried out a set of cross-correlation studies for two UHJs: KELT-9b and KELT-20b. Both planets orbit fast-rotating stars, which resulted in the detection of the strong Rossiter-McLaughlin (RM) effect and center-to-limb variations in the transmission spectrum. These effects had to be corrected to ensure a precise analysis. Using the transmission spectroscopy method, we detected 21 single lines of Fe II in the atmosphere of KELT-9b. All of the detected lines are blue-shifted, suggesting strong day-to-night side atmospheric winds. The cross-correlation method leads to the detection of the blue-shifted signal with a signal-to-noise ratio (S/N) of 13.46. Our results are in agreement with models based on non-local thermodynamical equilibrium (NLTE) effects, with a mean micro-turbulence of νmic = 2.73 ± 1.5 km s−1 and macro-turbulence of νmac = 8.22 ± 3.85 km s−1. In the atmosphere of KELT-20b, we detected 17 single lines of Fe II. Considering different measurements of the systemic velocity of the system, we conclude that the existence of winds in the atmosphere of KELT-20b cannot be determined conclusively. The detected signal with the cross-correlation method presents a S/N of 11.51. The results are consistent with NLTE effects, including means of νmic = 3.04 ± 0.35 km s−1 and νmac = 6.76 ± 1.17 km s−1.

Analysis of vericiguat via ion-pairing with eosin Y as a spectrofluorimetric and spectrophotometric probe: Application to content uniformity test

Using spectroscopy, quick and sensitive analytical methods based on Eosin Y ion pairing were developed and assessed in order to determine vericiguat with high selectivity and sensitivity. The drug is used for treating symptomatic chronic heart failure (HF), The quenching impact of vericiguat on the Eosin Y’s fluorescence at a pH 3.3, in 0.1 M acetate buffer solution was observed using spectrofluorometric technique. This technique is regarded as the original spectrofluorometric technique for the assay of vericiguat. The quenching effect on fluorescence was ranged from 100 to 1000 ng mL−1. The absorbance of the generated ion-pair was measured using spectrophotometric method at 550 nm in aqueous buffered solutions with pH 3.3. In the concentration range of 1.0–10.0 µg mL−1, Beer’s law was followed. The two approaches were applied to the analysis of dosage forms with a high percent recovery successfully, and they were assessed in compliance with ICH guidelines. Moreover, the method’s sustainability was evaluated and compared to the published method using two greenness assessment tools termed analytical eco-scale and Analytical GREENness (AGREE). That findings suggest that the method is more sustainable than the published method.

Stabilisation of a Strontium Hydride with a Monodentate Carbazolyl Ligand and its Reactivity.

The molecular strontium hydride 2[(dtbpCbz)SrH(L)]2 (L = benzene, toluene) was isolated and stabilized by employing a sterically demanding carbazole ligand (dtbpCbz = 1,8-bis(3,5-ditert-butyl-phenyl)-3,6-ditertbutylcarbazolyl). Compound 2 was synthesized via phenylsilane metathesis with the corresponding amide (dtbpCbz)SrN(SiMe3)2 and characterized by 1HNMR, XRD and vibrational spectroscopy methods. We further investigated the stoichiometric reactivity of 2 towards carbon monoxide, azobenzene and trimethylsilylacetylene, showing three distinct reactivity pathways: addition, reduction and deprotonation. The reaction of 2 with carbon monoxide yields the ethenediolate complex 4 via addition, while with azobenzene reduction of the N-N double bond and release of hydrogen were observed, affording a heteroleptic strontium complex with a radical azobenzenyl ligand (5). The terminal alkyne is deprotonated by the hydride moiety to give the acetylide complex 6.

Non-contact measurement method of liquid composition using microwave radar cross-section

This study aims to provide a non-contact detection of liquid composition inside containers using Microwave Radar Cross-section (RCS) measurement technology. Firstly, it analyzes the limitations of traditional near-infrared spectroscopy methods and proposes the necessity of introducing microwave detection methods. The research demonstrates through experiments a significant correlation between polar substances like total acid content and radar scattering capability, showing microwave radar’s effectiveness in reflecting the polarity characteristics of liquids. Furthermore, theoretical derivations and experimental validations illustrate that differences in electromagnetic properties of different liquid components lead to variations in echo loss, thereby impacting RCS levels. Experimental results indicate that microwave radar RCS measurement technology achieves an accuracy level of 2%, capable of distinguishing between different concentrations of ethanol, acetic acid, and other solutions. This study highlights the significant advantages of microwave radar RCS measurement technology in non-contact detection of liquid composition, providing new methods and a technological foundation for precise liquid component detection.

Seawater-corrosion-engineered CoNi electrode for highly efficient oxidation of 5-(Hydroxymethyl)furfural

The green synthesis of 2,5-furandicarboxylic acid (FDCA), famous as a bio-based polymer monomer from the 5-hydroxymethylfurfural (HMF), offers a promising route to reduce the usage of petroleum-based polymer polyethylene terephthalate. Although the electrocatalytic preparation of FDCA rids high temperature and pressure limits, most electrocatalysts used in the HMF oxidation reaction (HMFOR) are usually fabricated in harsh conditions. Therefore, we propose a method to improve the performance of electrocatalysts in the HMFOR reaction by introducing metal salts using natural seawater as the main feedstock. The final Co-sw/NF realized a 97.4% FDCA yield and 97.3% Faraday efficiency (FE). In-situ Raman techniques identified the catalytically active species of the catalysts employed in the HMFOR process. The effect of metal salts on catalyst energy levels is discussed in detail using the ultraviolet photoelectron spectroscopy (UPS) and Tauc plot method. The adsorption performance of HMF on the catalyst was determined by calculating the d-band centers and applying open circuit potential (OCP) tests. Furthermore, we elucidate the specific mechanism in terms of electron transport pathways.

Green synthesis of zinc nanoparticles by hydroalcoholic extract of lavender (Lavandula stoechas L.), characterization, and cytotoxic effects on human breast and colon cancer

Green synthesis is the production of metal nanoparticles (MNPs) with biological agents, including plant extracts; it is environmentally friendly. The study aimed to investigate the cytotoxic effects of zinc nanoparticles (ZnNPs) synthesized by the hydroalcoholic extract of lavender (Lavandula stoechas L.) against MCF7 and HT29 with the approach of identifying the ability of these NPs to produce anticancer drugs. ZnNPs are synthesized using the hydroalcoholic extract of the lavender. Nanoparticles (NPs) are evaluated and characterized by the Tyndall effect, UV-Vis, DLS, FT-IR, Zeta-P, Raman spectroscopy, SEM, AFM, and XRD methods. The cytotoxic effects of produced NPs against MCF7 and HT29 and the healthy cell lines MCF10a and HGF were measured using the MTT Assay. Results show the average size of ZnNPs is 40 and 50 nm at a concentration of 3 mM. The highest level of cytotoxicity of NPs occurred after 48 h and was dependent on dose and time. It was determined that lavender is a suitable option for the green synthesis of ZnNPs and can be used as a stable source for the production of MNPs. Also, the synthesized ZnNPs showed cytotoxic effects against the examined cancer cells, while they did not cause toxicity to healthy cells.

Surface-modified dendrimer nanoconjugate for targeting delivery of rifampicin

ObjectiveThe study aimed to formulate and evaluate the efficiency of surface-modified Polyamidoamine dendrimer (PAMAM) as a targeted nanocarrier for the antimycobacterial agent rifampicin. MethodsThe periphery of dendrimer was modified with mannose using α-D-mannopyranosylphenyl isothiocyanate and characterized using analytical techniques i.e., infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). Then, rifampicin was encapsulated into mannosylated dendrimers and evaluated for size, shape, encapsulation efficiency (EE%), drug-dendrimer interaction, and drug release. The toxicity of the nanoconjugates were assessed towards macrophages using the MTT technique. The study investigated the internalization of dendrimer nanoparticles into macrophages to assess the impact of mannose conjugation. Dendrimers were fluorescently labelled and the internalization was quantified using a fluorescence spectroscopy and flow cytometer methods. ResultsMannosylated dendrimers with different mannose densities were successfully developed. The nanoparticles were within the nanoscopic scale. The dendrimers appeared spheroidal under scanning electron microscopy (SEM), and thermal analysis confirmed the conjugation of rifampicin into the dendrimers. The nanoparticles exhibited a good EE% for rifampicin at 10.34 % w/w. After surface mannosylation, the EE% further increased, ranging from 43.43 % to 57.91 % w/w. Mannose-functionalized dendrimers prolonged rifampicin release in physiological pH, while a rapid release in pH 4.5 medium was noticed. The cytotoxicity of the dendrimers in RAW macrophages was considerably reduced after mannose functionalization. In vitro studies indicated that mannose significantly increased the macrophage uptake of nanoconjugates, likely via lectin receptor-mediated endocytosis. ConclusionOverall results suggested mannosylated dendrimers as an effective targeted pulmonary delivery system for rifampicin with negligible cytotoxicity.

Magnetically-assembled multifunctional Fe3O4@SiO2@Au particles for SERS detection of low-concentration dye molecules

Abstract Surface-enhanced Raman scattering (SERS) is a sensitive spectroscopic method to detect low concentration-low volume analytes. Owing to this, there has been a rising interest in developing improved as well as novel nanostructured substrates for SERS applications. For SERS applications, it is desirable to have large-scale assemblies of such nanostructures that can sustain multiple electromagnetic ‘hotspots’ for improved sensitivity. In this work, we use magnetic-field aided large-scale assembly of multifunctional magnetic-plasmonic particles to generate a large area SERS substrate. The particles, composed of a Fe3O4 core with a thin silica coating followed by Au nanoparticles (Fe3O4@SiO2@Au), were synthesized by simple chemical methods. The multifunctional particles were characterized using powder x-ray diffraction, transmission electron microscopy, Raman spectroscopy, and SQUID magnetometer. Magnetic assembly of the composite particles, carried out using a bi-electromagnet setup, was used for SERS detection of organic dyes such as rhodamine B and methylene blue. Using this scheme, it was possible to detect ultra-low concentrations (up to 1fM) of the dye molecules. This method is promising for applications such as chemical sensors, biomolecular detection, cancer detection, and hyperthermia treatment, forensic investigations, and drug delivery.