Voltammetric biosensor for coronavirus spike protein using magnetic bead and screen-printed electrode for point-of-care diagnostics.

The rapid spread of the novel human coronavirus 2019 (COVID-19) and its morbidity have created an urgent need for rapid and sensitive diagnostics. The real-time polymerase chain reaction is the gold standard for detecting the coronavirus in various types of biological specimens. However, this technique is time consuming, labor intensive, and expensive. Screen-printed electrodes (SPEs) can be used as point-of-care devices because of their low cost, sensitivity, selectivity, and ability to be miniaturized. The ability to detect the spike protein of COVID-19 in serum, urine, and saliva was developed using SPE aided by magnetic beads (MBs) and a portable potentiostat. The antibody-peroxidase-loaded MBs were the captured and catalytic units for the electrochemical assays. The MBs enable simple washing and homogenous deposition on the working electrode using a magnet. The assembly of the immunological MBs and the electrochemical system increases the measuring sensitivity and speed. The physical and electrochemical properties of the layer-by-layer modified MBs were systematically characterized. The performance of these immunosensors was evaluated using spike protein in the range 3.12-200 ng mL-1. We achieved a limit of detection of 0.20, 0.31, and 0.54 ng mL-1 in human saliva, urine, and serum, respectively. A facile electrochemical method to detect COVID-19 spike protein was developed for quick point-of-care testing.

Multivariate analysis of metabolic parameters and optimization of antibody production using high cell density hybridoma in hollow fiber bioreactors.

OBJECTIVES: The relationships of manipulation of culture temperature and medium circulation rate on the metabolic parameters were regressed by multiple linear regression analysis in hollow fiber bioreactors (HFB). RESULTS: The high circulation rate could significantly enhance the oxygen consumption of the hybridoma cells and the medium's oxidation-reduction potential. A mildly hypothermic condition of 36 °C and a circulation rate of 182.5 mL/min could support the hybridoma had the maximal antibody titer of 60.75 µg/mL for 20 days. When the ammonium ion was 65 ppm or lactate close to 2.6 g/L, the medium was replaced to maintain the stable and healthy cells at the high cell concentration of 3.33 × 108/mL for continuous antibody production. Two serum-free media could be successfully applied to this perfusion system and maintain hybridoma growth and antibody production. CONCLUSION: The single-use HFBs could provide the advantages including high cell density, low shear stress, and continuous antibody production.

Systemic effects after intravitreal injection of bevacizumab in new born rabbit eyes.

PURPOSE: To determine the systemic impact of intravitreal injection of bevacizumab (IVB), an anti-vascular endothelium growth factor antibody, in newborn rabbits. MATERIALS AND METHODS: We used four groups of rabbits. Group 1 rabbits received a single injection of IVB starting from the age of 6 weeks. Group 2 rabbits received a single injection of balanced salt solution (BSS, 0.025 ml) and served as controls for group 1. Group 3 rabbits received two consecutive injections of IVB at the ages of 6 and 10 weeks. Group 4 rabbits received two consecutive injections of BSS at the ages of 6 and 10 weeks and served as controls for group 3. During the experiment, a complete blood count (CBC), clinical biochemistry, weight gain, food intake, body temperature, blood pressure, pulse, and mortality were measured in the animals. Two months after IVB injection, the animals were sacrificed, and histology of the major organs was checked. Immunohistochemistry was assessed to explore the neurons in the central nervous system (CNS). RESULTS: We found there were no morphological or functional changes in the eyes following IVB injection. Furthermore, there were no differences in CBC, biochemistry, or other measured parameters among the four groups of animals. We checked the histology of the major organs and neurons in the CNS and they did not reveal significant differences among the four groups of animals. CONCLUSIONS: Conclusively, IVB of either one or two injections (0.625 mg) in newborn rabbit eyes is well tolerated and does not cause noticeable systemic organ pathology.

In vitro scleral lutein distribution by cyclodextrin containing nanoemulsions.

Lutein is a macular pigment that contributes to maintaining eye health. The development of lutein-laden nanocarriers for ocular delivery would have the advantages of user friendliness and cost-effectiveness. Nano-scaled vehicles such as cyclodextrin (CD) and nanoemulsion could overcome the barriers caused by the scleral structure. This study focused on the development of hybrid nanocarriers containing nanoemulsion and CD for scleral lutein accumulation. In the presence of the nanoemulsion, CD forms such as ßCD and hydroxyethyl (HE) ßCD increased the partition of lutein into the porcine sclera. A combination of nanoemulsion and 2% HEßCD enhanced lutein accumulation to 119±6 µg g(-1) h(-1), which was 9.2-fold higher than that with lutein suspension alone. We explored the dose effect of CD in nanoemulsion on scleral lutein and found that the scleral accumulation of lutein was enhanced by increasing the CD content. The novel nanoemulsion had 95% drug-loading efficiency and low cytotoxicity in retinal cells. The CD-modified nanoemulsion not only improved the stability and entrapment efficacy of lutein in the aqueous system but also enhanced scleral lutein accumulation. An increase in the partition coefficient of lutein in porcine sclera when using the CD-modified nanoemulsion was also confirmed.

Magnetic metal-organic frameworks as sensitive aptasensors for coronavirus spike protein.

Electrochemical biosensors, known for their low cost, sensitivity, selectivity, and miniaturization capabilities, are ideal for point-of-care devices. The magnetic metal-organic framework (MMOF), synthesized using the in-situ growth method, consists of ferric salt, magnetic nanoparticles, histidine, and benzene tetracarboxylic acid. MMOF was sequentially modified with aptamer-biotin and streptavidin-horseradish peroxidase, serving as a detector for spike protein and a transducer converting electrochemical signals using H2O2-hydroquinone on a screen-printed electrode. MMOF facilitates easy washing and homogeneous deposition on the working electrode with a magnet, enhancing sensitivity and reducing noise. The physical and electrochemical properties of the modified MMOFs were thoroughly characterized using various analytical techniques. The aptasensors' performance achieved a detection limit of 6 pM for voltammetry and 5.12 pM for impedance spectroscopy in human serum samples. This cost-effective, portable MMOF platform is suitable for rapid point-of-care testing for SARS-CoV-2 spike proteins.

In vitro anti-propionibacterium activity by curcumin containing vesicle system.

Propionibacterium acnes acts a critical role in the development of inflammatory acne when it overgrows in pilosebaceous units. The spread of multiple drug resistance bacteria indicates a growing need for new antimicrobial agents. The objective of this study is to develop lipid vehicles to deliver curcumin and inhibit P. acnes in the skin. The inhibitory activities of the curcumin containing vehicles against P. acnes were studied by the bioluminescence assay. Curcumin accumulation patterns in neonate pig skin were studied using Franz diffusion cells and confocal laser scanning microscopy. The physicochemical properties of the curcumin containing vehicles including interfacial tension, size distribution and viscosity were analyzed. Significant curcumin accumulation (362±8 µg/g skin) was observed with the lipid vehicles developed herein. Curcumin (0.43 µg/mL) in the vehicles significantly inhibited the growth of P. acnes. Confocal laser scanning microscopy confirmed the formation of curcumin reservoir in the skin by the curcumin-loaded vehicles. Curcumin-loaded vehicles could efficiently accumulate in the skin and inhibit P. acnes in vitro. Our results highlight the potential of using vehicles containing lauric acid and curcumin as an alternative treatment for acne vulgaris.

Synthesis and characterization of Au-decorated graphene oxide nanocomposite for magneto-electrochemical detection of SARS-CoV-2 nucleocapsid gene.

Fast and effective diagnosis is the first step in monitoring the current coronavirus 2 (CoV-2) pandemic. Herein, we establish a simple and sensitive electrochemical assay using magnetic nanocomposite and DNA sandwich probes to rapidly quantify the CoV-2 nucleocapsid (N) gene down to the 0.37 fM level. This assay uses a pair of specific DNA probes. The capture probe is covalently conjugated to Au-decorated magnetic reduced graphene oxide (AMrGO) nanocomposite for efficiently capturing target RNA. In contrast, the detection probe is linked to peroxidase for signal amplification. The probes target the COV-2 gene, allowing for specific magnetic separation, enzymatic signal amplification, and subsequent generation of voltammetric current with a total assay time of 45 min. The developed biosensor has high selectivity and can discriminate non-specific gene sequences. Synthetic COV-2 N-gene can be detected efficiently in serum and saliva, while 1-bp mismatch gene yielded a low response. The performance of the genosensor was good in an extensive linear range of 5 aM-50 pM. For synthetic N-gene, we achieved the detection limit of 0.37, 0.33, and 0.19 fM in human saliva, urine, and serum. This simple, selective, and sensitive genosensor could have various genetics-based biosensing and diagnostic applications.

Magnetic graphene oxide nanoflakes for dual RNA interfering delivery and gene knockdown in prostate and liver cancers.

The development of synthetic carriers for small interfering RNA (siRNA) and plasmids is crucial for effective gene therapy. In this study, we synthesized magnetic graphene oxide nanoflakes as carriers for siRNA delivery, with the goal of knockdown specific genes such as the green fluorescence protein (GFP). Our approach combined magnetically reduced graphene oxide with polyethylenimine (PEI) crosslinked to its surface using carbonyl diimidazole. To evaluate the adsorption capacity of the PEI-modified nanocomposite, we investigated its ability to bind two types of nucleic acids: short-hairpin (sh)RNA plasmids and siRNA targeting GFP. The nanocomposite exhibited significant adsorption, with maximum capacities of 426 ng/µg for shRNA and 71 ng/µg for siRNA, respectively. Simultaneous delivery of siRNA and shRNA using our designed nanocomposites was successfully achieved in human hepatoma and prostate cancer cells. Under magnetic guidance, the knockdown efficiencies reached 73.5 % in hepatoma cells for dual delivery of siRNA and shRNA. Our findings revealed that the nanocomplexes were internalized by the cells through a caveolae-dependent endocytosis mechanism. The demonstrated ability of the nanoflakes to efficiently transport siRNA and shRNA, with high loading capacity, controlled release, and magnetic targeting, resulted in effective GFP knockdown in vitro. These findings highlight the potential of magnetic graphene oxide nanoflakes as promising carriers for siRNA delivery and gene knockdown in therapeutic applications.

Efficient vitreolysis by combining plasmin and sulfur hexafluoride injection in a preclinical study in rabbit eyes.

PURPOSE: To investigate the efficacy of plasmin and sulfur hexafluoride (SF(6)) on the vitreoretinal junction, as well as the long-term safety in the eye and effect on the recipient's general health after application in the eye. METHODS: The study design included four groups of rabbits with three animals in each group. Group 1 received an intravitreal injection (IVI) of plasmin and SF(6) in the right eye; group 2 received an IVI of plasmin in the right eye; group 3 received an IVI of SF(6) in the right eye; and group 4 received an IVI of balanced salt solution in the right eye, which served as a normal control. Long-term safety (up to approximately three months) after plasmin and/or SF(6) injection was evaluated morphologically by clinical examination, histology, and immunohistochemistry, and functionally by electroretinograms (ERGs). General health evaluations after intravitreal injection included the assessment of weight gain, food intake, body temperature, and complete blood count analysis. RESULTS: Plasmin plus SF(6) injection resulted in complete posterior vitreous detachment (PVD), whereas plasmin or SF(6) injection alone resulted in only partial PVD. Balanced salt solution did not induce PVD. Eighty days after intravitreal injection, there were no major differences among the eyes of the three groups of animals compared with the normal control animals upon clinical evaluation, or regarding retinal morphology and ERGs. The lenses examined remained clear for up to 80 days following the intravitreal injection of plasmin plus SF(6), except one eye in the plasmin-treated group. ERGs decreased transiently one week after intravitreal injection in groups 1 through 3, but animals recovered fully to normal status afterward. General health was not affected after the injection of plasmin plus SF(6). CONCLUSIONS: Efficient vitreoretinal separation could be achieved, and an acceptable long-term safety profile was noted after plasmin plus SF(6) injection in the eye. No major ocular toxicity or systemic toxicity was found after the injection of plasmin plus SF(6). These results provide good support for the future clinical use of plasmin plus SF(6) for treatment of a variety of vitreoretinopathies.

Antimicrobial activity of curcumin-loaded myristic acid microemulsions against Staphylococcus epidermidis.

The bactericidal properties of myristic acid and curcumin were revealed in a number of studies. However, whether curcumin-loaded myristic acid microemulsions can be used to inhibit Staphylococcus epidermidis, which causes nosocomial infections, has not been reported. Our aim was to develop curcumin-loaded myristic acid microemulsions to inhibit S. epidermidis on the skin. The interfacial tension, size distribution, and viscosity data of the microemulsions were characterized to elucidate the physicochemical properties of the curcumin microemulsions. Curcumin distribution in neonate pig skin was visualized using confocal laser scanning microscopy. Dermal curcumin accumulation (326 µg/g skin) and transdermal curcumin penetration (87 µg/cm(2)/d) were obtained with the microemulsions developed herein. Curcumin at the concentration of 0.86 µg/mL in the myristic acid microemulsion could inhibit 50% of the bacterial growth, which was 12 times more effective than curcumin dissolved in dimethyl sulfoxide (DMSO). The cocktail combination of myristic acid and curcumin in the microemulsion carrier synergistically inhibited the growth of S. epidermidis. The results we obtained highlight the potential of using curcumin-loaded microemulsions as an alternative treatment for S. epidermidis-associated diseases and acne vulgaris.

Multifunctional magnetic nanocarriers for delivery of siRNA and shRNA plasmid to mammalian cells: Characterization, adsorption and release behaviors.

Nucleic acids are promising candidates for treating various diseases. Nucleic acid is negatively charged and hydrophilic; therefore, it is not efficiently taken up by cells. Successful gene therapy requires the development of carriers for efficient delivery of gene-expressing DNA plasmid and small interfering RNA (siRNA) duplex. In this study, we developed MNP-CA-PEI, a citric acid (CA)-modified magnetic nanoparticle (MNP) cross-linked with polyethyleneimine (PEI), using carbonyldiimidazole as the crosslinker. The physical properties of MNP-CA-PEI (particle size, morphologies, surface coating, surface potentials, magnetic hystereses, superparamagnetic behaviors, and infrared spectra) were systematically characterized by transmission electron microscopy imaging, dynamic light scattering, thermogravimetric analysis, superconducting quantum interference device, and Fourier transform infrared spectroscopy. The adsorption isotherm and kinetics were determined by the Langmuir model, the Freundlich model, a pseudo-first-order equation, and a pseudo-second-order equation. MNP-CA-PEI could form polyelectrolyte complexes with negatively charged nucleic acids, enabling the efficient delivery of nucleic acids into cells. Using MNP-CA-PEI nanoparticles, we magnetically triggered the intracellular delivery of green fluorescence protein (GFP)-expressing DNA plasmid, plasmid-expressing short hairpin RNA (shRNA) against GFP, or siRNA targeting GFP into different cell lines. Nucleic acid/MNP-CA-PEI displayed the enhanced cellular uptake of GFP-expressing DNA plasmid, and it improved the silencing efficiency of shRNA and siRNA, determined by fluorescence imaging. Gene knockdowns mediated by shRNA and siRNA were also confirmed by a quantitative real-time polymerase chain reaction. MNP-CA-PEI delivered nucleic acids into cytosol through caveolae-mediated endocytosis. This study introduces a new MNP functionalization that can be used for the magnetically driven intracellular delivery of nucleic acids.

Tetraethylenepentamine-Coated ß Cyclodextrin Nanoparticles for Dual DNA and siRNA Delivery.

Nucleic acid reagents, including plasmid-encoded genes and small interfering RNA (siRNA), are promising tools for validating gene function and for the development of therapeutic agents. Native ß-cyclodextrins (BCDs) have limited efficiency in gene delivery due to their instable complexes with nucleic acid. We hypothesized that cationic BCD nanoparticles could be an efficient carrier for both DNA and siRNA. Tetraethylenepentamine-coated ß-cyclodextrin (TEPA-BCD) nanoparticles were synthesized, characterized, and evaluated for targeted cell delivery of plasmid DNA and siRNA. The cationic TEPA coating provided ideal zeta potential and effective nucleic acid binding ability. When transfecting plasmid encoding green fluorescent protein (GFP) by TEPA-BCD, excellent GFP expression could be achieved in multiple cell lines. In addition, siRNA transfected by TEPA-BCD suppressed target GFP gene expression. We showed that TEPA-BCD internalization was mediated by energy-dependent endocytosis via both clathrin-dependent and caveolin-dependent endocytic pathways. TEPA-BCD nanoparticles provide an effective means of nucleic acid delivery and can act as potential carriers in future pharmaceutical application.

Development and characterization of eucalyptol microemulsions for topic delivery of curcumin.

Microemulsions have received great attention for applications in transdermal drug delivery. The use of curcumin for treating various skin diseases like scleroderma, psoriasis, and skin cancer was extensively reported. The solubility of curcumin in various oils, surfactants, and cosurfactants was studied herein in order to find the optimal components for a transdermal delivery vehicle. Microemulsion systems composed of eucalyptol, polysorbate 80, ethanol, and water were developed as transdermal delivery vehicles for curcumin. Effects of the microemulsion composition on transdermal curcumin delivery were studied using Franz diffusion cells. The transdermal curcumin flux, permeability coefficient, and enhancement ratio were analyzed to evaluate the effects of eucalyptol/water ratios in the microemulsions. Pseudo-ternary phase diagrams of the eucalyptol microemulsions with various surfactant/cosurfactant ratios (1:1-1:3) were constructed to investigate their phase behaviors. Conductivity, interfacial tension, size, and viscosity data of the microemulsions were used to characterize the physicochemical properties of transdermal vehicles. The influence of the microemulsions on skin histology and on the delivery route was analyzed using hematoxylin/eosin staining and confocal laser scanning microscopy. In conclusion, microemulsions were successfully developed for transdermal curcumin delivery after screening various components and adjusting the oil/water ratios. The curcumin permeation rate of the microemulsion developed was 15.7-fold higher than that of the control (eucalyptol only). These results indicate that an eucalyptol microemulsion system is a promising tool for the percutaneous delivery of curcumin.

Electrochemical immunosensor for serum parathyroid hormone using voltammetric techniques and a portable simulator.

An electrochemical platform based on a screen-printed carbon electrode (SPCE) is developed to detect parathyroid hormone (PTH). A nanocomposite of multi-walled carbon nanotube (MWCNT) and gold nanoparticles (AuNP) was deposited on the SPCE to immobilize antibodies and horseradish peroxidase (HRP). MWCNT improved the stability and conductivity of the immunosensor because of its good electron-transfer ability and tubular structure. The AuNP not only provided a large surface area for antibody immobilization, but it also enhanced the electrochemical signal for enzyme-linked immunosensing. Cyclic voltammetry showed both electron transfer and the effective surface area were increased on the modified electrode. The characteristics of the modified SPCE were assayed by Raman spectroscopy, scanning electron microscopy, atomic force microscopy, and electrochemical techniques. The linear detection range of this PTH immunosensor was within 1-300 pg/ml, and the electrochemical performance was not affected by interference from protein components in human serum. After storage at 4 °C for 28 days, 85% PTH sensing ability of this immunosensor was maintained compared to the freshly prepared one using the SWV and DPV methods. The relative standard deviations of all measurements were within 3-8% for both voltammetric methods. These results indicated the developed immunosensor had good stability and reproducibility. This PTH immunosensor had a detection limit of 0.886 and 0.065 pg/ml for the differential pulse voltammetry and square wave voltammetry, respectively. We provided a quick analysis of serum PTH which might be used as an electrochemical immunosensing platform for point-of-care testing.

MicroRNA-126 inhibits pathological retinal neovascularization via suppressing vascular endothelial growth factor expression in a rat model of retinopathy of prematurity.

Vascular endothelial growth factor (VEGF) is the principal growth factor responsible for the retinal neovascularization in the pathogenesis of retinopathy of prematurity (ROP). Current therapies for ROP include laser ablation and intravitreal anti-VEGF injection. However, these treatments either destroy the peripheral retina or associate with problems of persistent peripheral avascular retina or later recurrence of ROP. In the present study we investigated a new therapeutic approach by exploring the potential role of a specific microRNA, miR-126, in regulating VEGFA expression and retinal neovascularization in a rat oxygen-induced retinopathy (OIR) model. We demonstrated that miR-126 mimic and plasmid effectively suppresses VEGFA mRNA expression in both human and rat retinal pigment epithelium cell lines, quantified with qRT-PCR. Animal experiments on rat OIR model revealed that intravitreal injection of miR-126 plasmid efficiently downregulated VEGFA expression in the intraocular fluid and retinal tissues measured by ELISA, and significantly suppressed retinal neovascularization, which was confirmed by calculating sizes of neovascularization areas on fluorescence microscopic images of flat mounted retina stained with Alexa Fluor 594-conjugated isolectin B4 to visualize blood vessels. Together, these results showed that intravitreal injection of miR-126 plasmid could inhibit retinal neovascularization by down-regulating VEGFA expression, suggesting a potential therapeutic effect for ROP.

Characterization and formulation optimization of solid lipid nanoparticles in vitamin K1 delivery.

BACKGROUND: Solid lipid nanoparticle (SLN) systems have been applied to various drugs and delivery routes. Vitamin K1 is an important cofactor for maintaining hemostasis and preventing hemorrhage. METHOD: Vitamin K1-loaded SLNs are systematically being developed by optimizing triglycerides and lipophilic and hydrophilic surfactants based on the size and stability of the resulting SLNs. Concentrations of the surfactants, Myverol and Pluronic, were optimized by a central composite design and response surface methodology. Vitamin K1 (phylloquinone) was used as a lipophilic drug in the SLN system to evaluate the potential for oral delivery. RESULTS: Vitamin K1-loaded SLNs had a mean size of 125 nm and a zeta potential of -23 mV as measured by photon correlation spectroscopy. The prepared SLNs were examined by differential scanning calorimetry and transmission electron microscopy and found to have an imperfect crystalline lattice and a spherical morphology. Effects of ultrasonication duration and drug load on the particle size and entrapment efficiency of the SLNs were also evaluated. CONCLUSION: More than 85% of the vitamin K1 was entrapped in SLNs when the payload was <5%. The vitamin K1 in SLNs was stable for a 54-h duration in simulated gastric and intestinal fluids. The particle size and vitamin K1 entrapped in the SLN were stable after 4 months of storage at 25 degrees C. The results demonstrated that SLNs prepared herein can potentially be exploited as carriers for the oral delivery of vitamin K1.

Oligochitosan modified albumin as plasmid DNA delivery vector: Endocytic trafficking, polyplex fate, in vivo compatibility.

Cationic macromolecules condense DNA into small nanoparticles and form polyplex. The composition of the polyplex determines the endocytic process, the intracellular routing and the fate of the polyplex. Previously, oligochitosan-modified vectors with different protein moieties are used as gene delivery vector and the types of protein moiety can influence the endosome escape ability and transfection efficiency. Among the modified vectors, oligochitosan-modified bovine serum albumin (BSA) showed 90% transfection efficeincy compared to the modified zein and ovalbumin. These data encouraged us to investigate the mechanism of internalization involved in the superior transfection efficiency of modified BSA/ plasmid polyplex. The effect of specific endocytic inhibitors was studied in two adherent cell lines. The caveolae-mediated and lipid-mediated pathways play a significant role in the polyplex internalization. Next, a colocation of polyplex with lysosome was investigated in the presence of LysoTracker using confocal microscopy. Up to 70% of polyplex successfully escaped the lysosome without degradation. Four non-adherent cell lines showed above than 60% transfection efficiency at an optimized vector/plasmid ratio. Moreover, no significant hemolytic effect was observed up to 500 µg/mL of cationic BSA, indicating no detectable cell membrane disruption. Overall, the hybrid biomacromolecule showed good intracellular delivery and safety in a mice model.

Encapsulating curcumin in ethylene diamine-ß-cyclodextrin nanoparticle improves topical cornea delivery.

Curcumin is a powerful scavenger of reactive oxygen species and could prevent the corneal cells from oxidative damage. However, the clinical efficacy of curcumin is limited by its low aqueous solubility and stability, leading to poor bioavailability. ß-cyclodextrin, with a hydrophilic surface and a hydrophobic cavity and self-assembling properties, can form inclusion complexes with lipophilic drugs such as curcumin for ocular delivery. We synthesized ethylene diamine (EDA)-modified ß-cyclodextrin and prepared the curcumin complexation using the solvent evaporation method. The EDA-ß-cyclodextrin provided a better thermodynamic stability and higher complex yield for curcumin complexes, compared to ß-cyclodextrin, which were demonstrated on the analysis of their van't Hoff plots and phase solubility diagrams. We characterized EDA-ß-cyclodextrin curcumin nanoparticles and determined that the EDA modified ß-cyclodextrin is a more suitable carrier than parental ß-cyclodextrin, using FT-IR, XRD, TEM, and analyses of solubility and storage stability. In addition, the curcumin-EDA-ß-cyclodextrin nanoparticles had better in vitro corneal penetration and 3 -h cumulative flux in a porcine cornea experiment, and displayed an improved biocompatibility, confirmed by the histological examination of porcine corneas and cell viability of bovine corneal epithelial cells. These results together revealed a role of EDA modification in the ß-cyclodextrin carrier, including the improvement of curcumin complex formation, thermodynamic properties, cytotoxicity, and the in vitro corneal penetration. The EDA-ß-cyclodextrin inclusion can provide curcumin a higher degree of aqueous solubility and corneal permeability.

Biocompatible quantum dot-antibody conjugate for cell imaging, targeting and fluorometric immunoassay: crosslinking, characterization and applications.

Quantum dots (QDs) are important fluorescent probes that offer great promise for bio-imaging research due to their superior optical properties. However, QDs for live cell imaging and the tracking of cells need more investigation to simplify processing procedures, improving labeling efficiency, and reducing chronic toxicity. In this study, QDs were functionalized with bovine serum albumin (BSA) via a chemical linker. Anti-human immunoglobulin antibodies were oxidized by sodium periodate to create reactive aldehyde groups for a spontaneous reaction with the amine groups of BSA-modified QDs. An antibody-labeled QD bioconjugate was characterized using agarose gel electrophoresis, dynamic light scattering, and zeta potential. Using fluorescence spectroscopy, we found that the fluorescence of QDs was retained after multiple conjugation steps. The cell-labeling function of the QD bioconjugate was confirmed using an image analyzer and confocal microscopy. The QD bioconjugate specifically targeted human immunoglobulin on the membrane surface of recombinant cells. In addition, the QD bioconjugate applied in fluorometric immunoassay was effective for the quantitative analysis of human immunoglobulin in an enzyme-linked immunosorbent assay. The developed QD bioconjugate may offer a promising platform to develop biocompatible tools to label cells and quantify antibodies in the immunoassay.

Design and Verification of a Dry Sensor-Based Multi-Channel Digital Active Circuit for Human Brain Electroencephalography Signal Acquisition Systems.

A brain-computer interface (BCI) is a type of interface/communication system that can help users interact with their environments. Electroencephalography (EEG) has become the most common application of BCIs and provides a way for disabled individuals to communicate. While wet sensors are the most commonly used sensors for traditional EEG measurements, they require considerable preparation time, including the time needed to prepare the skin and to use the conductive gel. Additionally, the conductive gel dries over time, leading to degraded performance. Furthermore, requiring patients to wear wet sensors to record EEG signals is considered highly inconvenient. Here, we report a wireless 8-channel digital active-circuit EEG signal acquisition system that uses dry sensors. Active-circuit systems for EEG measurement allow people to engage in daily life while using these systems, and the advantages of these systems can be further improved by utilizing dry sensors. Moreover, the use of dry sensors can help both disabled and healthy people enjoy the convenience of BCIs in daily life. To verify the reliability of the proposed system, we designed three experiments in which we evaluated eye blinking and teeth gritting, measured alpha waves, and recorded event-related potentials (ERPs) to compare our developed system with a standard Neuroscan EEG system.