Optimization of localized surface plasmon resonance hot spots in surface-enhanced infrared absorption spectroscopy aluminum substrate as an optical sensor coupled to chemometric tools for the purity assay of quinary mixtures

Formulation of Saxagliptin Oral Films: Optimization, Physicochemical Characterization, In-Vivo Assessment, and In-Vitro Real-Time Release Monitoring via a Novel Polyaniline Nanoparticles-Based Solid-Contact Screen Printed Ion-Selective Electrode

Oral dispersible films have received broad interest due to fast drug absorption and no first-path metabolism, leading to high bioavailability and better patient compliance. Saxagliptin (SXG) is an antidiabetic drug that undergoes first-path metabolism, resulting in a less active metabolite, so the development of SXG oral dispersible films (SXG-ODFs) improves SXG bioavailability. The formula optimisation included a response surface experimental design and the impact of three formulation factors, the type and concentration of polymer and plasticiser concentration on in-vitro disintegration time and folding endurance. Two optimised SXG-ODFs prepared using either polyvinyl alcohol (PVA) or hydroxypropyl methylcellulose were investigated. SXG-ODFs prepared with PVA demonstrated a superior rapid disintegration time, ranging from 17 to 890 s, with the fastest disintegration time recorded at 17 s. These short durations can be attributed to the hydrophilic nature of PVA, facilitating rapid hydration and disintegration upon contact with saliva. Additionally, PVA-based films displayed remarkable folding endurance, surpassing 200 folds without rupture, indicating flexibility and stability. The high tensile strength of PVA-based films further underscores their robust mechanical properties, with tensile strength values reaching up to 4.53 MPa. SXG exhibits a UV absorption wavelength of around 212 nm, posing challenges for traditional quantitative spectrophotometric analysis, so a polyaniline nanoparticles-based solid-contact screen-printed ion-selective electrode (SP-ISE) was employed for the determination of SXG release profile effectively in comparison to HPLC. SP-ISE showed a better real-time release profile of SXG-ODFs, and the optimised formula showed lower blood glucose levels than commercial tablets.

Silver Nanoparticles: Multifunctional Tool in Environmental Water Remediation

Water pollution is a worldwide environmental and health problem that requires the development of sustainable, efficient, and accessible technologies. Nanotechnology is a very attractive alternative in environmental remediation processes due to the multiple properties that are conferred on a material when it is at the nanometric scale. This present review focuses on the understanding of the structure-physicochemical properties-performance relationships of silver nanoparticles, with the objective of guiding the selection of physicochemical properties that promote greater performance and are key factors in their use as antibacterial agents, surface modifiers, colorimetric sensors, signal amplifiers, and plasmonic photocatalysts. Silver nanoparticles with a size of less than 10 nm, morphology with a high percentage of reactive facets {111}, and positive surface charge improve the interaction of the nanoparticles with bacterial cells and induce a greater antibacterial effect. Adsorbent materials functionalized with an optimal concentration of silver nanoparticles increase their contact area and enhance adsorbent capacity. The use of stabilizing agents in silver nanoparticles promotes selective adsorption of contaminants by modifying the surface charge and type of active sites in an adsorbent material, in addition to inducing selective complexation and providing stability in their use as colorimetric sensors. Silver nanoparticles with complex morphologies allow the formation of hot spots or chemical or electromagnetic bonds between substrate and analyte, promoting a greater amplification factor. Controlled doping with nanoparticles in photocatalytic materials produces improvements in their electronic structural properties, promotes changes in charge transfer and bandgap, and improves and expands their photocatalytic properties. Silver nanoparticles have potential use as a tool in water remediation, where by selecting appropriate physicochemical properties for each application, their performance and efficiency are improved.

Comparing silver and gold nanoislands' surface plasmon resonance for bisacodyl and its metabolite quantification in human plasma

Gold and silver nanoparticles have witnessed increased scientific interest due to their colourful colloidal solutions and exceptional applications. Comparing the localized surface plasmon resonance (LSPR) of gold and silver nanoparticles is crucial for understanding and optimizing their optical properties. This comparison informs the design of highly sensitive plasmonic sensors, aids in selecting the most suitable nanoparticles for applications like surface-enhanced infrared spectroscopy (SEIRA) and biomedical imaging, and guides the choice between gold and silver nanoparticles based on their catalytic and photothermal properties. Ultimately, the study of LSPR facilitates the tailored use of these nanoparticles in diverse scientific and technological applications. Two SEIRA methods combined with partial least squares regression (PLSR) chemometric tools were developed. This development is based on the synthesis of homogeneous, high-dense deposited metal nanoparticle islands over the surface of glass substrates to be used as lab-on-chip SEIRA sensors for the determination of bisacodyl (BIS) and its active metabolite in plasma. SEM micrographs revealed the formation of metallic islands of colloidal citrate-capped gold and silver nanoparticles of average sizes of 29.7 and 15 nm, respectively. BIS and its active metabolite were placed on the nanoparticles' coated substrates to be directly measured, then PLSR chemometric modelling was used for the quantitative determinations. Plasmonic citrate-capped gold nanoparticle substrates showed better performance than those prepared using citrate-capped silver nanoparticles in terms of preparation time, enhancement factor, PLSR model prediction, and quantitative results. This study offers a way to determine BIS and its active metabolite in the concentration range 15-240 ng/mL in human plasma using inexpensive disposable glass-coated substrates that can be prepared in 1 h to get results in seconds with good recovery between 98.77 and 100.64%. The sensors provided fast, simple, selective, molecular-specific and inexpensive procedures to determine molecules in their pure form and biological fluid.

Advanced chemometric methods for simultaneous quantitation of caffeine, codeine, paracetamol, and p-aminophenol in their quaternary mixture

Two different multivariate techniques have been applied for the quantitative analysis of caffeine, codeine, paracetamol and p-aminophenol (PAP) in quaternary mixture, namely, Partial Least Squares (PLS-1) and Artificial Neural Networks (ANN). For suitable analysis, a calibration set of 25 mixtures with various ratios of the drugs and PAP impurity were established using a 4-factor 5-level experimental design. The most meaningful wavelengths for the chemometric models were chosen using Genetic Algorithm (GA) as a variable selection technique. By using an independent validation set, the validity of the proposed methods was evaluated. A comparative study was established between the three multivariate models (PLS-1, GA-PLS and GA-ANN). The comparison between the various models revealed that the GA-ANN model was superior at resolving the highly overlapped spectra of this quaternary combination. The drugs were successfully quantified in their pharmaceutical dosage form utilizing the GA-ANN models.

Direct Determination of Plasmon Enhancement Factor and Penetration Depths in Surface Enhanced IR Absorption Spectroscopy

Surface Enhanced Infrared Absorption Spectroscopy (SEIRAS) is a powerful tool for studying a wide range of surface and electrochemical phenomena. For most electrochemical experiments the evanescent field of an IR beam partially penetrates through a thin metal electrode deposited on top of an attenuated total reflection (ATR) crystal to interact with molecules of interest. Despite its success, a major problem that complicates quantitative interpretation of the spectra from this method is the ambiguity of the enhancement factor due to plasmon effects in metals. We developed a systematic method for measuring this, which relies upon independent determination of surface coverage by Coulometry of a surface-bound redox-active species. Following that, we measure the SEIRAS spectrum of the surface bound species, and from the knowledge of surface coverage, retrieve the effective molar absorptivity, ε_SEIRAS. Comparing this to the independently determined bulk molar absorptivity leads us to the enhancement factor f = ε_SEIRAS/ε_bulk. We report enhancement factors in excess of 1000 for the C-H stretches of surface bound ferrocene molecules. We additionally developed a methodical approach to measure the penetration depth of the evanescent field from the metal electrode into a thin film. Such systematic measure of the enhancement factor and penetration depth will help SEIRAS advance from a qualitative to a more quantitative method.

Identification of milk quality and adulteration by surface-enhanced infrared absorption spectroscopy coupled to artificial neural networks using citrate-capped silver nanoislands

Milk is one of the most important multicomponent superfoods owing to its rich macronutrient composition. It requires quality control at all the production stages from the farm to the finished products. A localized surface plasmon resonance optical sensor based on a citrate-capped silver nanoparticle (Cit-AgNP)–coated glass substrate was developed. The fabrication of such sensors involved a single-step synthesis of Cit-AgNPs followed by surface modification of glass slides to be coated with the nanoparticles. The scanning electron microscope micrographs demonstrated that the nanoparticles formed monolayer islands on glass slides. The developed surface-enhanced infrared absorption spectroscopy (SEIRA) sensor was coupled to artificial neural networking (ANN) for the qualitative differentiation between cow, camel, goat, buffalo, and infants’ formula powdered milk types. Moreover, it can be used for the quantitative determination of the main milk components such as fat, casein, urea, and lactose in each milk type. The qualitative results showed that the obtained FTIR spectra of cow and buffalo milk have high similarity, whereas camel milk resembled infant formula powdered milk. The most difference in FTIR characteristics was evidenced in the case of goat milk. The developed sensor adds several advantages over the traditional techniques of milk analysis using MilkoScan™ such as less generated waste, elimination of pre-treatment steps, minimal sample volume, low operation time, and on-site analysis.

Advanced chemometric methods as powerful tools for impurity profiling of drug substances and drug products: Application on bisoprolol and perindopril binary mixture

Impurity profiling has a rising importance nowadays due to the increased health problems associated with impurities and degradation products found in several drug substances and formulations. Three advanced, accurate and precise chemometric methods were developed as impurity profiling methods for a mixture of bisoprolol fumarate (BIS) and perindopril arginine (PER) with their degradation products which represent drug impurity or a precursor to such impurity. The methods applied were Partial Least Squares (PLS-1), Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) and Artificial Neural Networks (ANN). Genetic Algorithm (GA) was used as a variable selection tool to select the most significant wavelengths for the three chemometric models. For proper analysis, a 5-factor 5-level experimental design was used to establish a calibration set of 25 mixtures containing different ratios of the drugs and their degradation products (impurities). The validity of the proposed methods was assessed using an independent validation set. The designed models were able to predict the concentrations of the drugs and the degradation products/impurities in the validation set and pharmaceutical formulation. The proposed methods presented a powerful alternative to traditional and expensive chromatographic methods as impurity profiling tools.

The Potential Synergistic Activity of Zolmitriptan Combined in New Self-Nanoemulsifying Drug Delivery Systems: ATR-FTIR Real-Time Fast Dissolution Monitoring and Pharmacodynamic Assessment

Purpose

The current work aimed to overcome the poor permeability and undesirable adverse effects of Zolmitriptan (ZMT) and to increase its efficacy in the treatment of acute migraine by exploiting the synergistic effect of the essential oil, lavender, to fabricate ZMT self-nanoemulsifying drug delivery systems (ZMT-SNEDDS).

Methods

ZMT-SNEDDS were fabricated based on full factorial design (3²) to statistically assess the impact of oil and surfactant concentrations on the nanoemulsion globule size, zeta potential and percentage drug dissolution efficiency. An ATR-FTIR method was developed and validated for continuous real-time monitoring of ZMT dissolution and permeation. The dose of the optimized ZMT-SNEDDS used in the efficacy study was selected according to the acute toxicity study. The efficacy study was performed on migraineous rats induced by nitroglycerin and was evaluated by the activity cage and thermal tests, electroencephalogram, electroconvulsive stimulation, and biochemical analysis of brain tissue. Finally, histopathological and immunohistochemical examinations of the cerebra were carried out.

Results

Upon dilution, the optimized ZMT-SNEDDS (F5) exhibited nanosized spherical droplets of 19.59±0.17 nm with narrow size distribution, zeta potential (-23.5±1.17mV) and rapid emulsification characteristics. ATR-FTIR spectra elucidated the complete time course of dissolution and permeation, confirming F5 superior performance. Moreover, ZMT-SNEDDS (F5) showed safety in an acute toxicity study. ZMT concentration in rat brain tissues derived from F5 was lower compared to that of ZMT solution, yet its effect was better on the psychological state, algesia, as well as maintaining normal brain electrical activity and delayed convulsions. It counteracted the cerebral biochemical alternations induced by nitroglycerin, which was confirmed by histopathological examination.

Conclusion

In a nutshell, these findings corroborated the remarkable synergistic efficacy and the high potency of lavender oil-based ZMT-SNEDDS in migraine management compared to the traditional zolmitriptan solution.