In this work, we report a fiber optic biosensor for the label-free detection of vitamin D, by targeting the major circulating form of D3 in human body, i.e., 25-hydroxyvitamin D3 (25(OH)D3). The ...sensing platform relies on a long period grating (LPG) written into an unconventional fiber, i.e., double cladding fiber (DCF) with W-type refractive index profile. The sensitivity to surrounding medium is enhanced by chemical etching of the outer cladding as the working point of the device is tuned to the mode transition region. The DCF structure allows to combine the enhancement of the sensitivity (up to −1400 nm/RIU) with a good visibility of the grating resonance band (>10 dB) and long-term stability due to an all-silica structure. Moreover, the LPG transducer is coated with a nanosized layer of graphene oxide to provide carboxylic functional groups (-COOH) for the grafting of the biological recognition element for vitamin D3, i.e., a 25(OH)D3 specific antibody. To the best of our knowledge, this is the first evidence of a fiber optic biosensor for the detection of vitamin D3, which was performed using concentrations within the clinically relevant range of 1–1000 ng/mL and achieving a low limit of detection below 1.0 ng/mL in buffer solution that is well comparable with the state of the art. Finally, the performance of the biosensor was also evaluated in a complex medium with interfering proteins at physiological concentration obtaining promising results.
•First evidence of a label-free fiber optic biosensor for the detection of vitamin D.•Optical transducer based on a long period grating (LPG) in double cladding fiber.•Graphene oxide nanosized layer with functional groups for antibody binding.•Detection of 25-hydroxyvitamin D3 (25(OH)D3) concentrations within 1–1000 ng/mL.•Low limit of detection (LOD) below 1 ng/mL.
The formation of a dense monolayer of histidine‐tagged recombinant laccase on gold electrodes by using a short thiol‐NTA linker is described, as well as a kinetic analysis of the process by cyclic ...voltammetry. From a detailed analysis of the catalytic reduction of dioxygen by laccase in the presence of a one‐electron redox mediator it can be concluded that the immobilized enzyme remains as active as in homogeneous solution.
Enzymes stop! Histidine‐tagged laccase immobilization was performed on gold electrodes by using a short‐length thiol‐NTA linker (see figure). The catalytic reduction of O2, studied by cyclic voltammetry in the presence of a one‐electron redox mediator, revealed that the immobilized enzyme was as active as in solution.
Small molecular weight species such as miRNAs and other nucleic acid fragments are gaining an increased interest as biomarkers for relevant diseases. Also, cheap and rapid assays for their routine ...detection are becoming an urgent need. We have investigated the usability and convenience of a price affordable, label free and fast technique for their detection on a laboratory scale small device based on Bio-Layer Interferometry. Using a model DNA fragment (7 kDa), we have found that the technique is effectively fast and sensitive enough for the detection of nucleic acid fragments having a MW below the stated molecular size detection limit (10 kDa). The test molecule has been detected in solution at 100 nM in a direct capture experiment and up to about 10 nM following an improved approach where an enhancing probe is used to increase the apparent molecular dimensions of the analyte. The technique, following further optimizations, can be applied for the routine, cheap and fast analysis of small nucleic acid fragments that have a relevance in diagnosis and in therapy.
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•Label free and fast technique for nucleic acid detection on a laboratory scale.•Rapid and sensitive detection of DNA with MW below the BLI instrumental limits.•Applicability in routine qualitative and quantitative analyses combined with PCR.
Microgels (MGs) are synthetic colloidal hydrogel particles made of three dimensional polymer networks. Their chemical composition is crucial for their use as intelligent drug release systems operated ...by temperature control. Herein, several MGs using N‐isopropylacrylamide (Nipam)/N‐isopropylmethacrylamide (Nipmam), chitosan and acrylic/methacrylic acid have been synthesized by free radical polymerization reactions (NC MGs) and the effects of surfactants and different reaction times on size and swelling properties have been investigated. MGs have been identified and characterized by dynamic light scattering and atomic force microscopy, and finally used to optimize the encapsulation protocol of the hydrophobic drug sorafenib. The drug delivery system here described has encapsulation efficiency of 40% and releases 10% of the entrapped drug over about 16 h after the temperature is raised above the volume phase transition temperature. Data suggest that MGs with optimized composition may act as properly instructed entities able to trap and release biomolecules following external stimuli.
Currently, conventional treatments of hepatocellular carcinoma (HCC) are not selective enough for tumor tissue and lead to multidrug resistance and drug toxicity. Although sorafenib (SOR) is the ...standard first-line systemic therapy approved for the clinical treatment of HCC, its poor aqueous solubility and rapid clearance result in low absorption efficiency and severely limit its use for local treatment.
Herein, we present the synthesis of biodegradable polymeric Poly (D, L-Lactide-co-glycolide) (PLGA) particles loaded with SOR (PS) by emulsion-solvent evaporation process. The particles are carefully characterized focusing on particle size, surface charge, morphology, drug loading content, encapsulation efficiency, in vitro stability, drug release behaviour and tested on HepG2 cells. Additionally, PLGA particles have been coupled on side emitting optical fibers (
OF) integrated in a microfluidic device for light-triggered local release.
PS have a size of 248 nm, tunable surface charge and a uniform and spherical shape without aggregation. PS shows encapsulation efficiency of 89.7% and the highest drug loading (8.9%) between the SOR-loaded PLGA formulations. Treating HepG2 cells with PS containing SOR at 7.5 µM their viability is dampened to 40%, 30% and 17% after 48, 129 and 168 hours of incubation, respectively.
The high PS stability, their sustained release profile and the rapid cellular uptake corroborate the enhanced cytotoxicity effect on HepG2. With the prospect of developing biomedical tools to control the spatial and temporal release of drugs, we successfully demonstrated the potentiality of
OF for light-triggered local release of the carriers. Our prototypical system paves the way to new devices integrating microfluidics, optical fibers, and advanced carriers capable to deliver minimally invasive locoregional cancer treatments.
Drug delivery systems based on Human Serum Albumin (HSA) have been widely investigated due to their capability to interact with several molecules together with their nontoxicity, non-immunogenicity ...and biocompatibility. Sorafenib (SOR) is a kinase inhibitor used as the firstline treatment in hepatic cancer. However, because of its several intrinsic drawbacks (low solubility and bioavailability), there is a growing need for discovering new carriers able to overcome the current limitations.
To study HSA particles loaded with SOR as a thermal responsive drug delivery system.
A detailed spectroscopy analysis of the HSA and SOR interaction in solution was carried out in order to characterize the temperature dependence of the complex. Based on this study, the synthesis of HSA particles loaded with SOR was optimized. Particles were characterized by Dynamic Light Scattering, Atomic Force Microscopy and by spectrofluorometer. Encapsulation efficiency and in vitro drug release were quantified by RP-HPLC.
HSA particles were monodispersed in size (≈ 200 nm); encapsulation efficiency ranged from 25% to 58%. Drug release studies that were performed at 37 °C and 50 °C showed that HS5 particles achieved a drug release of 0.430 μM in 72 hours at 50 °C in PBS buffer, accomplishing a 4.6-fold overall SOR release enhancement following a temperature increase from 37 °C to 50 °C.
The system herein presented has the potential to exert a therapeutic action (in the nM range) triggering a sustained temperature-controllable release of relevant drugs.
Background: Trastuzumab, a therapeutic monoclonal antibody directed against HER2, is routinely used to treat HER2- positive breast cancer with a good response rate. However, concerns have arisen in ...the clinical practice due to adverse side effects. One way to overcome these limitations is to encapsulate trastuzumab in nanoparticles to improve cytotoxic activity, increase intracellular drug concentrations, escape the immune system and avoid systemic degradation of the drug in vivo. Methods: A double emulsion method was used to encapsulate trastuzumab into poly(lactic-co-glycolic) nanoparticles, effective for their biocompatibility and biodegradability. These nanocarriers, hereafter referred to as TZPs, were characterised in terms of size, homogeneity, zeta potential and tested for their stability and drug release kinetics. Finally, the TZPs cytotoxicity was assessed in vitro on the HER2 positive SKBR3 breast cancer cell line and compared to free trastuzumab. Results: The TZPs were stable, homogeneous in size, with a reduced zeta potential. They showed higher encapsulation efficiency and drug loading, a prolonged trastuzumab release kinetics that retained its physicochemical properties and functionality. TZPs showed a stronger cytotoxicity and increased apoptosis than similar doses of free trastuzumab in the cell line analysed. Confocal microscopy and flow cytometry assessed TZPs and trastuzumab cellular uptake while Western blot evaluated downstream signalling, overall HER2 content and shedding. Conclusion: TZPs exert more robust effects than free trastuzumab via a dual mode of action: TZPs are taken up by cells through an endocytosis mechanism and release the drug intracellularly for longer time. Additionally, the TZPs that remain in the extracellular space release trastuzumab which binds to the cognate receptor and impairs downstream signalling. This is the sole modality used by free trastuzumab. Remarkably, half dose of TZPs is as efficacious as the highest dose of free drug supporting their possible use for drug delivery in vivo. Keywords: PLGA nanoparticles, double-emulsion method, trastuzumab, breast cancer, signaling transduction
The aim of the present work is the study of the bacteriostatic/bactericidal effect of a silver-containing mesoporous bioactive glass obtained by evaporation-induced self-assembly and successive ...thermal stabilization. Samples of the manufactured mesophase were characterized by means of transmission electron microscopy and N
2
adsorption/desorption at 77 K, revealing structural and textural properties similar to SBA-15 mesoporous silica. Glass samples used for bioactivity experiments were put in contact with a standardized, commercially available cell culture medium instead of lab-produced simulated body fluid, and were then characterized by means of X-ray diffraction, field emission scanning electron microscopy and Fourier transform infrared spectroscopy. All these analyses confirmed the development of a hydroxyl carbonate apatite layer on glass particles. Moreover, the investigated mesostructure showed a very good antibacterial effect against
S. aureus
strain, with a strong evidence of bactericidal activity already registered at 0.5 mg/mL of glass concentration. A hypothesis about the mechanism by which Ag affects the bacterial viability, based on the intermediate formation of crystalline AgCl, was also taken into account. With respect to what already reported in the literature, these findings claim a deeper insight into the possible use of silver-containing bioactive glasses as multifunctional ceramic coatings for orthopedic devices.
Current technologies for pH monitoring still require the use of large and rigid tools that are not suitable for studying biological processes such as cell culture and tissue metabolism analysis. In ...this work, we report on a miniaturized cavity enhanced optrode based on lab-on-fiber technology for pH monitoring in liquid solutions. The device consists of a resonant cavity directly integrated on top of a single mode optical fiber, where the active medium is made of a responsive material (microgel) suitably synthesized to respond to pH variations. The pH variations in the liquid solution in which the probe is immersed modulate the optical cavity length, inducing a wavelength shift of the interference fringes in the reflection spectra. Remarkable sensitivities of up to 315 nm per pH unit are experimentally observed in the pH range from 4.6 to 5.8. Moreover, sensitivities >20 nm per pH unit are found in a wide pH range from 2.9 to 8. To the best of our knowledge, these represent the highest values reported so far with optical fiber based pH sensors. Our findings set the stage for the development of compact, flexible, and highly sensitive pH sensors, opening unexplored scenarios also for in vivo pH monitoring.
