Recent Advances of Optical Biosensors in Veterinary Medicine: Moving Towards the Point of Care Applications.

While food safety issues are attracting public concern due to their detrimental effects on human health, monitoring livestock health is urgently needed to diagnose animal diseases at an early stage by applying proper treatments, controlling, and preventing outbreaks, particularly in resource- limited countries. In addition, unhealthy farms are not only a threat to livestock but also to human lives. The available diagnostic techniques for the detection of key health threats within both the food and livestock sectors require labor-intensive and time-consuming experimental procedures and sophisticated and expensive instruments. To tackle this issue, optical biosensing strategies have been incorporated into point-of-care (POC) systems, offering real-time monitoring, field-deployable, and low-cost devices, which help make on-the-spot decisions. This review aims to discuss the recent cutting-edge research on POC optical biosensing platforms for on-farm diagnosis of animal diseases and on-site detection of animal-derived food-borne contaminants, including pathogens, antibiotics, and mycotoxins. Moreover, this review briefly presents the basic knowledge of various types of optical biosensors and their development using various recent strategies, including nanomaterial combinations, to enhance their performance in POC tests. This review is expected to help scientists to understand the evolution and challenges in the development of point-of-care biosensors for the food and livestock industry, benefiting global healthcare.

Radiolabeling of Preformed Niosomes with [99mTc]: In Vitro Stability, Biodistribution, and In Vivo Performance.

Nanocarriers radiolabeled with [99mTc] can be used for diagnostic imaging and radionuclide therapy, as well as tracking their pharmacokinetic and biodistribution characteristics. Due to the advantages of niosomes as an ideal drug delivery system, in this study, the radiolabeling procedure of niosomes by [99mTc]-HMPAO complexes was investigated and optimized. Glutathione (GSH)-loaded niosomes were prepared using a thin-film hydration method. To label the niosomes with [99mTc], the preformed GSH-loaded niosomes were incubated with the [99mTc]-HMPAO complex and were characterized for particle size, size distribution, zeta potential, morphology, and radiolabeling efficiency (RE). The effects of GSH concentration, incubation time, incubation temperature, and niosomal composition on RE were investigated. The biodistribution profile and in vivo SPECT/CT imaging of the niosomes and free [99mTc]-HMPAO were also studied. Based on the results, all vesicles had nano-sized structure (160-235 nm) and negative surface charge. Among the different experimental conditions that were tested, including various incubation times, incubation temperatures, and GSH concentrations, the optimum condition that resulted in a RE of 92% was 200-mM GSH and 15-min incubation at 40°C. The in vitro release study in plasma showed that about 20% of radioactivity was released after 24 h, indicating an acceptable radiolabeling stability in plasma. The biodistribution of niosomes was clearly different from the free radiolabel. Niosomes carrying radionuclide were successfully used for tracking the in vivo disposition of these carriers and SPECT/CT imaging in rats. Furthermore, biodistribution studies in tumor-bearing mice revealed higher tumor accumulation of the niosomal formulation as compared with [99mTc]-HMPAO.

Effect of Surfactant Type, Cholesterol Content and Various Downsizing Methods on the Particle Size of Niosomes.

The present study was conducted to investigate the performance of different size reduction techniques including probe sonication, extrusion, and high pressure homogenization for nanosizing of niosomes. Also, the effects of cholesterol content and surfactant type on the size and poly dispersity index (PDI) of the formulations were evaluated. Various niosomal formulations composed of Brij 72, Span 60, or Tween 60 were prepared and then, to reduce vesicle size and minimize the PDI, the niosomes were treated by various post-processing procedures. Surfactant type showed a significant effect on the particle size of the niosomes. The particle size of Tween 60 niosomes was significantly larger than those of Span 60 and Brij 72 niosomes (P < 0.05), indicating that at the same cholesterol content, niosomes composed of a surfactant with a higher HLB value show larger particle size than those with a lower HLB value. The influences of cholesterol content as well as downsizing methods, on the particle size and distribution of niosomes were significantly dependent on the surfactant composition of the niosomes. Extrusion and probe sonication were found to be the most efficient methods for size reduction of the Tween 60 and Span 60 niosomes, while for downsizing of Brij 72 niosomes, all employed methods were efficient and resulted in the approximately similar size of about 200 nm. In conclusion, the selection of an efficient method for nanosizing of niosomes and also achievement of a desired size range, and homogeneity highly depends on the niosome composition, particularly on the employed surfactant type.

Preparation, In-Vitro Characterization and Pharmacokinetic Evaluation of Brij Decorated Doxorubicin Liposomes as a Potential Nanocarrier for Cancer Therapy.

The aim of current study was to investigate the effect of Brij decoration of liposomes on in-vitro and in-vivo characteristics of the nanocarriers. Two hydrophilic Brij surfactants (Brij 35 and Brij 78) with almost similar molecular weight but differing in acyl chain were incorporated into liposomal bilayers at two percentages (5% and 10%). Conventional liposomes (CL) containing egg phosphatidylcholine and cholesterol as well as Brij-enriched liposomal dispersions were prepared and characterized. In-vivo pharmacokinetics of various liposomal formulations and drug solution (six groups) was studied after intravenous administration to rats. Conventional and Brij enriched doxorubicin (DOX) liposomes had small size within 82-97 nm and showed homogenous distribution (PDI < 0.1). Drug encapsulation was higher than 97% in all liposomes. The drug release profiles proved sustained DOX release from various formulations. Based on the results of in-vivo studies, all five liposomes increased drug exposure and plasma concentration in comparison to free drug. However, DOX liposomes enriched with 5% of either Brij 35 or Brij 78 showed higher AUC values and lower clearance. Overall, Brij surfactants (5% of bilayer lipids) could be potentially used to improve liposomal pharmacokinetic parameters.

Synthesis and Biological Evaluation of Cyclic [99mTc]-HYNIC-CGPRPPC as a Fibrin-Binding Peptide for Molecular Imaging of Thrombosis and Its Comparison with [99mTc]-HYNIC-GPRPP.

PURPOSE: Many patients worldwide suffer from cardiovascular diseases for which an underlying factor is thrombosis. Devising a molecular imaging technique for early detection of thrombosis in a clinical setting is highly recommended. Because fibrin is a major constituent of clots and is present in all types of thrombi but absent in circulation, it is a highly specific and sensitive target for molecular imaging of thrombi. It is assumed that cyclization of peptides will improve the receptor binding affinity and stability of the peptide. In the present study, we have developed linear and cyclic fibrin-binding peptides for thrombus imaging and compared their biological properties. PROCEDURES: Linear HYNIC-GPRPP and cyclic HYNIC-CGPRPPC peptides were synthesized using a standard Fmoc strategy and radiolabeled with Tc-99m. The stability of the radiolabeled peptides in human plasma and their affinity for fibrin and blood clots were determined. Blood clearance and biodistribution were evaluated in rats and mice, respectively. The peptide with the highest affinity was injected to a live rabbit femoral thrombosis model, and scintigraphic images were obtained. RESULTS: In vitro studies show that peptides are stable in human plasma and have a high affinity for human fibrin. They also demonstrated fast blood clearance in rats and high thrombus uptake in the Balb/c mice femoral thrombosis model. Femoral thrombosis was visualized 30 min postinjection of cyclic peptide in a live rabbit model using single photon emission computed tomography (SPECT)/X-ray computed tomography. CONCLUSIONS: The results indicate that the cyclic peptide is a promising agent for molecular imaging of fibrin using SPECT.