Search Results (60)

Time-domain (TD) diffuse reflectance can be modeled using diffusion theory (DT) to non-invasively estimate optical transport coefficients of biological media, which serve as markers of tissue physiology. We employ an optimized N-layer DT solver in cylindrical geometry to reconstruct optical coefficients of bilayered media from TD reflectance generated via Monte Carlo (MC) simulations. Optical properties for 384 bilayered tissue models representing human head or limb tissues were obtained from the literature at three near-infrared wavelengths. MC data were fit using the layered DT model to simultaneously recover transport coefficients in both layers. Bottom-layer absorption was recovered with errors under 0.02 cm⁻¹, and top-layer scattering was retrieved within 3 cm⁻¹ of input values. In contrast, recovered bottom-layer scattering had mean errors exceeding 50%. Total hemoglobin concentration and oxygen saturation were reconstructed for the bottom layer to within 10 μM and 5%, respectively. Extracted transport coefficients were significantly more accurate when obtained using layered DT compared to the conventional, semi-infinite DT model. Our results suggest using improved theoretical modeling to analyze TD reflectance analysis significantly improves recovery of deep-layer absorption. Full article

Self-calibrating and dual-slope measurements have been used in the field of diffuse optics for robust assessment of absolute values or temporal changes in the optical properties of highly scattering media and biological tissue. These measurements employ optical probes with a minimum of two source positions and a minimum of two detector positions. This work focuses on a quantitative analysis of the impact of errors in these source and detector positions on the assessment of optical properties. We considered linear, trapezoidal, and rectangular optode arrangements and theoretical computations based on diffusion theory for semi-infinite homogeneous media. We found that uncertainties in optodes’ positions may have a greater impact on measurements of absolute scattering versus absorption coefficients. For example, a 4.1% and 19% average error in absolute absorption and scattering, respectively, can be expected by displacing every optode in a linear arrangement by 1 mm in any direction. The impact of optode position errors is typically smaller for measurements of absorption changes. In each geometrical arrangement (linear, trapezoid, rectangular), we identify the direction of the position uncertainty for each optode that has minimal impact on the optical measurements. These results can guide the optimal design of optical probes for self-calibrating and dual-slope measurements. Full article

This study examines the cytotoxicity of two silver nanoparticle formulations—AgNPs conjugated with chlorhexidine (AgNPs-CHL) and AgNPs conjugated with polyethylene glycol and metronidazole (AgNPs-PEG-MET)—as examples of the surface functionalization of silver nanoparticles with drugs via sulfur–silver bonds and nitrogen–silver interactions. We previously reported the synthesis of these NPs and their efficiency in periodontitis treatment. Here, we analyze the relationships between the cytotoxic mechanisms of AgNPs and their surface chemistry. UV–Vis spectroscopy, dynamic light scattering (DLS), and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX) were used for physicochemical studies of the conjugates in two environments: aqueous solutions and commonly used cell culture media. Cytotoxicity was assessed in human fetal osteoblasts (hFOB 1.19) and human gingival fibroblasts (HGF-1) through BrdU and LDH assays, ROS detection, cell cycle analysis, apoptosis assays, and protein expression studies. AgNPs-CHL showed aggregation and increased hydrodynamic diameters in the culture medium, while AgNPs-PEG-MET remained stable. Both exhibited concentration-dependent cytotoxicity: AgNPs-CHL at 0.4–10 μg/mL and AgNPs-PEG-MET at 0.75–10 μg/mL. AgNPs-CHL, in which silver surface functionalization was realized via nitrogen–silver interactions, induced significant ROS generation, LDH release, and necroptosis, marked by increased RIP1, RIP3, and MLKL proteins. In the case of AgNPs-PEG-MET, where sulfur–silver bonds combined the drug via a PEG linker, they triggered apoptosis, as evidenced by elevated caspase-2 levels and flow cytometry. These findings highlight that the type of surface functionalization of silver nanoparticles significantly influences their physicochemical behavior and biological effects. Understanding these mechanisms is crucial in designing safer, more effective nanoparticle-based therapies for periodontal and other inflammatory conditions. Full article

Background/Objectives: Clarithromycin (CLA) is a widely used antibiotic effective against a variety of bacterial strains, making it a common treatment for respiratory, skin, and soft tissue infections. Moreover, extensive studies have confirmed the anticancer activity of CLA against different cancers, particularly when combined with conventional therapies. This study investigates the potential anticancer and antibacterial activities of developed CLA-loaded bovine serum albumin nanoparticles (CLA-BSA NPs), designed with optimized physicochemical properties to enhance drug delivery. Methods: The CLA-BSA NPs were synthesized using the desolvation method, followed by drug loading. Characterization techniques, including Dynamic Light Scattering (DLS), Fourier-Transform Infrared (FTIR) Spectroscopy, X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Thermogravimetric Analysis (TGA). Results: The results confirmed that CLA interacts with BSA NPs through van der Waals forces. The performance of drug–nanocarrier interaction was further assessed through in vitro drug release studies. The release studies demonstrated that CLA had a robust release profile in reductive media, with a cumulative release of 50.9% in acetate buffer (pH 5.0) supplemented with 10 mM glutathione (GSH). Further biological activity assays were also conducted, including cell viability assays (MTT) and antibacterial activity tests. CLA-BSA NPs demonstrated anticancer activity against the lung cancer (A549) cell line, while showing minimal cytotoxicity on normal human dermal fibroblast (HDF) cells. The antibacterial activity was assessed against Streptococcus pyogenes, Bacillus cereus, and Staphylococcus aureus. Among the tested strains, Bacillus cereus exhibited the highest sensitivity, with a minimum inhibitory concentration (MIC) of 0.032 µg/mL, compared to 0.12 µg/mL for Staphylococcus aureus and >32 µg/mL for Streptococcus pyogenes. Conclusions: In conclusion, these findings highlight CLA-BSA NPs as a promising drug delivery system that enhances the anticancer and antibacterial efficacy of CLA. Full article

The development of robust, real-time optical methods for the detection and tracking of particles in complex, multiple-scattering media is a problem of practical importance in a number of fields, including environmental monitoring, air quality assessment, and homeland security. In this paper, we develop a holographic, optical-theorem-based method for the detection of particles embedded in complex environments where wavefronts undergo strong multiple scattering. The proposed methodology is adaptive to a complex medium, which is integral to the sensing apparatus and thereby enables constant monitoring through progressive adaptation. This feature, along with the holographic nature of the developed approach, also renders (as a byproduct) real-time imaging capabilities for the continuous tracking of particles traversing the region under surveillance. In addition, the proposed methodology also enables the development of customized sensors that leverage a controllable complex multiple-scattering medium and the derived holographic sensing technology for real-time particle detection and tracking. We demonstrate, with the help of realistic computer simulations, holographic techniques capable of detecting and tracking small particles under such conditions and analyze the role of multiple scattering in enhancing detection performance. Potential applications include the identification of aerosolized biological substances, which is critical for biosecurity, and the rapid detection of hazardous airborne particles in confined or densely populated areas. Full article

Imaging technologies based on vector optical fields hold significant potential in the biomedical field, particularly for non-invasive scattering imaging of anisotropic biological tissues. However, the dynamic and anisotropic nature of biological tissues poses severe challenges to the propagation and reconstruction of vector optical fields due to light scattering. To address this, we propose a deep learning-based polarization-resolved restoration method aimed at achieving the efficient and accurate imaging reconstruction from speckle patterns generated after passing through anisotropic and dynamic time-varying biological scattering media. By innovatively leveraging the two orthogonal polarization components of vector optical fields, our approach significantly enhances the robustness of imaging reconstruction in dynamic and anisotropic biological scattering media, benefiting from the additional information dimension of vectorial optical fields and the powerful learning capacity of a deep neural network. For the first time, a hybrid network model is designed that integrates convolutional neural networks (CNN) with a Transformer architecture for capturing local and global features of a speckle image, enabling adaptive vectorial restoration of dynamically time-varying speckle patterns. The experimental results demonstrate that the model exhibits excellent robustness and generalization capabilities in reconstructing the two orthogonal polarization components from dynamic speckle patterns behind anisotropic biological media. This study not only provides an efficient solution for scattering imaging of dynamic anisotropic biological tissues but also advances the application of vector optical fields in dynamic scattering environments through the integration of deep learning and optical technologies. Full article

The effectiveness of photodynamic therapy (PDT) for cancer treatment relies on the generation of cytotoxic singlet oxygen (¹O₂) in type II PDT. Hence, monitoring of ¹O₂ generation during PDT enables optimal treatment delivery to the tumor target with reduced off-target effects. Direct ¹O₂ observation by measuring its luminescence at 1270 nm remains challenging due to the very weak signal. This study presents ¹O₂ luminescence measurements using a time-resolved singlet oxygen luminescence detection system (TSOLD) applied to protoporphyrin IX (PpIX) in different solvents (ethanol and acetone) and biological media (bovine serum albumin and agarose-based solid phantom). The compact experimental setup includes a nanosecond diode laser with a function generator, a cuvette with photosensitizer solution, optical filtering and mirrors, an InGaAs single-photon avalanche diode detector, and time-tagger electronics. Increasing the concentration of PpIX in these media from 1 to 10 µg/g resulted in a 3–5 × increase in the ¹O₂ luminescence signal. Furthermore, increasing light scattering in the sample using Intralipid from 0.1 to 1% led to a decrease in the ¹O₂ luminescence signal and lifetime. These results confirm the marked effect of the microenvironment on the ¹O₂ signal and, hence, on the photodynamic efficacy. Full article

Significance: We present a system to measure and analyze the complete polarization state distribution of speckle patterns generated from in vivo tissue. Accurate measurement of polarization speckle requires both precise spatial registration and rapid polarization state acquisition. A unique measurement system must be designed to achieve accurate images of polarization speckle patterns for detailed investigation of the scattering properties of biological tissues in vivo. Aim and approach: This system features a polarization state analyzer with no moving parts. Two pixel-polarizer cameras allow for the instantaneous acquisition of the spatial Stokes vector distribution of polarization speckle patterns. System design and calibration methods are presented, and representative images from measurements on liquid phantoms (microsphere suspensions) and in vivo healthy and tumor murine models are demonstrated and discussed. Results and Conclusions: Quantitative measurements of polarization speckle from microsphere suspensions with controlled scattering coefficients demonstrate differences in speckle contrast, speckle size, and the degree of polarization. Measurements on in vivo murine skin and xenograft tumor tissue demonstrate the ability of the system to acquire snapshot polarization speckle images in living systems. The developed system can thus rapidly and accurately acquire polarization speckle images from different media in dynamic conditions such as in vivo tissue. This capability opens the potential for future detailed investigation of polarization speckle for in vivo biomedical applications. Full article

Natural polysaccharides can serve as carriers of genes owing to their intrinsic biocompatibility, biodegradability, and low toxicity. Additionally, they can be easily chemically modified, e.g., through grafting, leading to hybrid synthetic–biological copolymers with additional functionalities. In this work we report on the electrostatic interaction between a chitosan-g-poly(N-isopropylacrylamide) (Chit-g-PNIPAM) copolymer and DNA macromolecules of different lengths (i.e., 50 and 2000 bp), towards the construction of polyplexes that can serve as potential gene delivery systems. At the basic science level, the work aims to elucidate the effects of DNA length on the structural and physicochemical properties of the thermoresponsive hybrid macromolecular assemblies. The protonated amino groups on the chitosan backbone enable electrostatic binding with the anionic phosphate groups of the DNA molecules, while the PNIPAM side chains are expected to impart thermoresponsive properties to the formed polyplexes. Different amino to phosphate group (N/P) mixing ratios were examined, aiming to produce stable dispersions. The physicochemical properties of the resulting polyplexes were investigated by dynamic and electrophoretic light scattering (DLS and ELS), while their morphology was studied by scanning-transmission electron microscopy (STEM). Moreover, their response to changes in temperature and ionic strength, as well as their stability against biological media, was also examined. Finally, the binding affinity of the copolymer towards DNA was evaluated through fluorescence spectroscopy, using ethidium bromide quenching assays, while infrared spectroscopy was used to investigate the structure of the incorporated DNA chains. Full article

Nano- and micro-sized vesicular and colloidal structures mediate cell–cell communication. They are important players in the physiology of plants, animals, and humans, and are a subject of increasing interest. We investigated the effect of three surfactants, N-cetylpyridinium chloride (CPC), sodium dodecyl sulfate (SDS), and Triton X-100 (TX100), and two anionic polyelectrolytes, sodium polystyrene sulfonate (NaPSS) and sodium polymethacrylate (NaPMA), on nanoliposomes. In addition, the effect of SDS and TX100 on selected biological membranes (erythrocytes and microalgae) was investigated. The liposomes were produced by extrusion and evaluated by microcalorimetry and light scattering, based on the total intensity of the scattered light (I_tot), hydrodynamic radius (R_h), radius of gyration (R_g), shape parameter p (=R_h/R_g,0), and polydispersity index. The EPs shed from erythrocytes and microalgae Dunaliella tertiolecta and Phaeodactylum tricornutum were visualized by scanning electron microscopy (SEM) and analyzed by flow cytometry (FCM). The R_h and I_tot values in POPC liposome suspensions with added CPC, SDS, and TX100 were roughly constant up to the respective critical micelle concentrations (CMCs) of the surfactants. At higher compound concentrations, I_tot dropped towards zero, whereas R_h increased to values higher than in pure POPC suspensions (R_h ≈ 60–70 nm), indicating the disintegration of liposomes and formation of larger particles, i.e., various POPC–S aggregates. Nanoliposomes were stable upon the addition of NaPSS and NaPMA, as indicated by the constant R_h and I_tot values. The interaction of CPC, SDS, or TX100 with liposomes was exothermic, while there were no measurable heat effects with NaPSS or NaPMA. The SDS and TX100 increased the number density of EPs several-fold in erythrocyte suspensions and up to 30-fold in the conditioned media of Dunaliella tertiolecta at the expense of the number density of cells, which decreased to less than 5% in erythrocytes and several-fold in Dunaliella tertiolecta. The SDS and TX100 did not affect the number density of the microalgae Phaeodactylum tricornutum, while the number density of EPs was lower in the conditioned media than in the control, but increased several-fold in a concentration-dependent manner. Our results indicate that amphiphilic molecules need to be organized in nanosized particles to match the local curvature of the membrane for facilitated uptake. To pursue this hypothesis, other surfactants and biological membranes should be studied in the future for more general conclusions. Full article

Ultrasmall nanoparticles (diameter 2 nm) of silver, platinum, and bimetallic nanoparticles (molar ratio of Ag:Pt 0:100; 20:80; 50:50; 70:30; 100:0), stabilized by the thiolated ligand glutathione, were prepared and characterized by transmission electron microscopy, differential centrifugal sedimentation, X-ray photoelectron spectroscopy, small-angle X-ray scattering, X-ray powder diffraction, and NMR spectroscopy in aqueous dispersion. Gold nanoparticles of the same size were prepared as control. The particles were fluorescently labeled by conjugation of the dye AlexaFluor-647 via copper-catalyzed azide-alkyne cycloaddition after converting amine groups of glutathione into azide groups. All nanoparticles were well taken up by HeLa cells. The cytotoxicity was assessed with an MTT test on HeLa cells and minimal inhibitory concentration (MIC) tests on the bacteria Escherichia coli and Staphylococcus xylosus. Notably, bimetallic AgPt nanoparticles had a higher cytotoxicity against cells and bacteria than monometallic silver nanoparticles or a physical mixture of silver and platinum nanoparticles. However, the measured release of silver ions from monometallic and bimetallic silver nanoparticles in water was very low despite the ultrasmall size and the associated high specific surface area. This is probably due to the surface protection by a dense layer of thiolated ligand glutathione. Thus, the enhanced cytotoxicity of bimetallic AgPt nanoparticles is caused by the biological environment in cell culture media, together with a polarization of silver by platinum. Full article

In shallow tissues of the human body, pathological changes often occur, and there are several kinds of scattering media, such as mucosa, fat, and blood, present on the surface of these tissues. In such scattering environments, it is difficult to distinguish the location of the lesions using traditional attenuation-based imaging methods, while polarization-based imaging methods are more sensitive to this information. Therefore, in this paper, we conducted experiments using diluted milk to simulate biological tissues with scattering effects, illuminated with non-polarized light sources, and used an optimized robust polarization de-scattering algorithm for image processing. The results were qualitatively and quantitatively analyzed through local intensity comparison and visual fidelity functions, verifying the effectiveness of this algorithm under specific conditions. Full article

Curcumin is known for its anti-inflammatory, neuroprotective, and antioxidant properties, but its use in biological applications is hindered by its sensitivity to light, oxygen, and temperature. Furthermore, due to its low water solubility, curcumin has a poor pharmacokinetic profile and bioavailability. In this study, we evaluated the potential application of curcumin as a neuroprotective agent encapsulated in RGD peptide-PEGylated nanoliposomes developed from salmon-derived lecithin. Salmon lecithin, rich in polyunsaturated fatty acids, was used to formulate empty or curcumin-loaded nanoliposomes. Transmission electron microscopy, dynamic light scattering, and nanoparticle tracking analysis characterizations indicated that the marine-derived peptide-PEGylated nanoliposomes were spherical in shape, nanometric in size, and with an overall negative charge. Cytotoxicity tests of curcumin-loaded nanoliposomes revealed an improved tolerance of neurons to curcumin as compared to free curcumin. Wild-type SH-SY5Y were treated for 24 h with curcumin-loaded nanoliposomes, followed by 24 h incubation with conditioned media of SH-SY5Y expressing the Swedish mutation of APP containing a high ratio of Aβ40/42 peptides. Our results revealed significantly lower Aβ-induced cell toxicity in cells pre-treated with RGD peptide-PEGylated curcumin-loaded nanoliposomes, as compared to controls. Thus, our data highlight the potential use of salmon lecithin-derived RGD peptide PEGylated nanoliposomes for the efficient drug delivery of curcumin as a neuroprotective agent. Full article

Surface-enhanced Raman scattering (SERS) is a powerful technique for decoding of 2-5-component mixes of analytes. Low concentrations of analytes and complex biological media are usually non-decodable with SERS. Recognition molecules, such as antibodies and aptamers, provide an opportunity for a specific binding of ultra-low contents of analyte dissolved in complex biological media. Different approaches have been proposed to provide changes in SERS intensity of an external label upon binding of ultra-low contents of the analytes. In this paper, we propose a SERS-based sensor for the rapid and sensitive detection of botulinum toxin type A. The silver nanoisland SERS substrate was functionalized using an aptamer conjugated with a Raman label. The binding of the target affects the orientation of the label, providing changes in an analytical signal. This trick allowed detecting botulinum toxin type A in a one-stage manner without additional staining with a monotonous dose dependence and a limit of detection of 2.4 ng/mL. The proposed sensor architecture is consistent with the multiarray detection systems for multiplex analyses. Full article

The adsorption of biomolecules on nanoparticles’ surface ultimately depends on the intermolecular forces, which dictate the mutual interaction transforming their physical, chemical, and biological characteristics. Therefore, a better understanding of the adsorption of serum proteins and their impact on nanoparticle physicochemical properties is of utmost importance for developing nanoparticle-based therapies. We investigated the interactions between potentially therapeutic proteins, neurotrophin 3 (NT3), brain-derived neurotrophic factor (BDNF), and polyethylene glycol (PEG), in a cell-free system and a retinal pigmented epithelium cell line (ARPE-19). The variance in the physicochemical properties of PEGylated NT3–BDNF nanoparticles (NPs) in serum-abundant and serum-free systems was studied using transmission electron microscopy, atomic force microscopy, multi-angle dynamic, and electrophoretic light scattering. Next, we compared the cellular response of ARPE-19 cells after exposure to PEGylated NT3–BDNF NPs in either a serum-free or complex serum environment by investigating protein release and cell cytotoxicity using ultracentrifuge, fluorescence spectroscopy, and confocal microscopy. After serum exposure, the decrease in the aggregation of PEGylated NT3–BDNF NPs was accompanied by increased cell viability and BDNF/NT3 in vitro release. In contrast, in a serum-free environment, the appearance of positively charged NPs with hydrodynamic diameters up to 900 nm correlated with higher cytotoxicity and limited BDNF/NT3 release into the cell culture media. This work provides new insights into the role of protein corona when considering the PEGylated nano–bio interface with implications for cytotoxicity, NPs’ distribution, and BDNF and NT3 release profiles in the in vitro setting. Full article