Anti-IgG Doped Melanin Nanoparticles Functionalized Quartz Tuning Fork Immunosensors for Immunoglobulin G Detection: In Vitro and In Silico Study.

The quartz tuning fork (QTF) is a promising instrument for biosensor applications due to its advanced properties such as high sensitivity to physical quantities, cost-effectiveness, frequency stability, and high-quality factor. Nevertheless, the fork's small size and difficulty in modifying the prongs' surfaces limit its wide use in experimental research. Our study presents the development of a QTF immunosensor composed of three active layers: biocompatible natural melanin nanoparticles (MNPs), glutaraldehyde (GLU), and anti-IgG layers, for the detection of immunoglobulin G (IgG). Frequency shifts of QTFs after MNP functionalization, GLU activation, and anti-IgG immobilization were measured with an Asensis QTF F-master device. Using QTF immunosensors that had been modified under optimum conditions, the performance of QTF immunosensors for IgG detection was evaluated. Accordingly, a finite element method (FEM)-based model was produced using the COMSOL Multiphysics software program (COMSOL License No. 2102058) to simulate the effect of deposited layers on the QTF resonance frequency. The experimental results, which demonstrated shifts in frequency with each layer during QTF surface functionalization, corroborated the simulation model predictions. A modelling error of 0.05% was observed for the MNP-functionalized QTF biosensor compared to experimental findings. This study validated a simulation model that demonstrates the advantages of a simulation-based approach to optimize QTF biosensors, thereby reducing the need for extensive laboratory work.

Stimuli-responsive nanoparticle-nanofiber hybrids for drug delivery and photodynamic therapy.

Hybrid nanomaterials possess integrated multi-components to syncretize various properties and functions within a single entity. Owing to this synergistic effect, they promise efficient anti-cancer therapy. In line with this target, we produced stimuli-responsive nanoparticle-nanofiber hybrids (NNHs) via embedding photoresponsive natural melanin nanoparticles (MNPs) within a biocompatible polycaprolactone (PCL) nanofiber matrix. Electrospinning was performed to produce monolithic and core-shell structured NNHs using a single and a coaxial nozzle. The NNHs were upgraded to drug delivery systems by model hydrophilic drug-ampicillin (amp)-loading. The drug release results showed that monolithic PCL meshes displayed a burst release, whereas nanohybrid formation with MNPs improved the release profile toward Fickian diffusion. Core-shell NNH presented a more sustained drug release profile than its MNP-free replica and monolithic NNH because its encapsulating shell layer hindered the diffusion of the drug. The photodynamic therapy accompanied by UV-A-irradiation on monolithic and core-shell NNHs yielded up to 34 % and 37 % malignant melanoma cell death. Moreover, this study proved the potency of MNPs-enhanced NNHs in drug delivery and photodynamic therapy applications. Even so, more efforts should be concerted to unlock unknown features of the NNHs, which have the power to advance emerging areas, including but not limited to material science, biosensing, and theranostics.

Monitoring of pollution in the western Black Sea coast of Turkey by striped red mullet (Mullus surmuletus).

The striped red mullet (Mullus surmuletus) is an economically important demersal fish species. In this study, our aim was to monitor the pollution in the western Black Sea coast of Turkey using striped red mullet as a bioindicator species. Fish samples were caught from four different locations in the western Black Sea coast of Turkey in 2006, 2009-2011, and 2016. Highly elevated cytochrome P4501A (CYP1A)-related 7-ethoxyresorufin O-deethylase (EROD) activities were measured in striped red mullet caught from Zonguldak Harbor in all of the sampling years. The lowest EROD activities were measured in fish samples caught from Kefken. In addition to the EROD activity measurements, glutathione S-transferase (GST), glutathione reductase, and catalase activities were also measured in the striped red mullet samples. Higher GST and catalase activities were measured in the striped red mullet samples caught from Zonguldak Harbor than from Kefken in 2016. These results indicate that the striped red mullet is responsive to CYP1A inducer pollutants. This study covers intermittent measurements of the biomonitoring data from the striped red mullet caught around the western Black Sea coast of Turkey, over a 10-year period.

A comparative study of single-needle and coaxial electrospun amyloid-like protein nanofibers to investigate hydrophilic drug release behavior.

In this study, nanofibers containing an amyloid-like bovine serum albumin (AL-BSA) carrier and a model drug (ampicillin) were produced by electrospinning. The release behavior of ampicillin was compared from electrospun nanofibers prepared as either coaxial or single-needle types. SEM images showed that the membranes had a uniform and smooth structure and the core/shell fibers were found to be thicker than the core fibers. Core/shell production was proved by transmission electron microscopy images. Fourier transform infrared spectroscopy indicated the existence of compatibility between ampicillin and the AL-BSA matrix. The in vitro antimicrobial properties of ampicillin were studied through the comparison of bacterial inhibition zones and ampicillin was found to be more effective against Gram-positive Staphylococcus aureus than Gram-negative Escherichia coli. Moreover, in vitro drug release tests were conducted to explore the relationship between the shell thickness and the drug release rate. A burst release was observed for all membranes owing to the small fiber diameters and thus short diffusion lengths. For core membranes, the drug release mechanism followed Fickian transport, which was close to zero-order kinetic. A typical biphasic release mechanism was observed for the core/shell nanofibers. Overall, we present the first evidence of AL-BSA as a potential core/shell drug mediator.

Controlled release of a hydrophilic drug from electrospun amyloid-like protein blend nanofibers.

In this study, a controlled drug release platform, amyloid-like bovine serum albumin (AL-BSA) with ampicillin sodium salt (amp), was developed. To develop this platform, 5%, 10%, and 20% (w/w) ratios of amp:BSA were used with electrospinning to prepare nanofibers with average diameters of 132±69, 159±60, and 179±42nm, respectively. Fourier transform infrared spectroscopy demonstrated that AL-BSA could entrap large amounts of drug inside the nanofibers, which was attributed to the antimicrobial activity of the released drug against Escherichia coli and Staphylococcus aureus. The amount of drug released was measured by UV-VIS spectrophotometry. The nanofibrous matrix of the electrospun membrane showed controlled release behavior in all samples. The transport mechanism was Fickian for the low ratio of amp:BSA (5% w:w). When the drug ratio was increased to >10% (w:w), thicker fiber structures formed, suggesting that the drug traveled a longer distance to reach the fiber surface; thus, the mechanism of transport shifted from Fickian to non-Fickian.

Amyloid-like protein nanofibrous membranes as a sensing layer infrastructure for the design of mass-sensitive biosensors.

Quartz crystal microbalances (QCMs) have been used in the literature for mass sensitive biosensor applications. However, their performance, reliability and stability have been limited by the chemical treatment steps required for the functionalization and activation of the QCM surface, prior to antibody immobilization. Specifically, these steps cause increased film thickness, which diminishes performance by mass overload, and create a harsh environment, which reduces biological activity. In this work, we eliminated this chemical step by introducing a sensing layer modification using electrospun amyloid like-bovine serum albumin (AL-BSA) nanofibers on QCM surfaces. Owing to the self-functionality of AL-BSA nanofibers, these modified QCM surfaces were directly activated by glutaraldehyde (GA). To assess the performance of these modified electrodes, a model protein, lysozyme (Lys), was selected as the biological agent to be immobilized. Frequency measurements were performed in batch (dip-and-dry) and continuous (flow-cell) processes, and binding performances were compared. AL-BSA modified surfaces were characterized by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), quartz crystal microbalance (QCM), contact angle (CA) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). Protein detection was measured based on the frequency shift before and after the covalent bonding of Lys. Under optimized conditions, the proposed immobilization platforms could bind 335ng/mL and 250ng/mL of Lys for batch and continuous processes, respectively. Our results demonstrate the potential usage of these self-functional electrospun AL-BSA infrastructure sensing layers on QCM surfaces. This modification enables the direct immobilization of bioactive agents by eliminating any surface functionalization process for further mass-sensitive biosensor applications.