Fluorescein Isothiocyanate-conjugated Albumin Research Articles

Functionalization of Carbon Electrode Surface Using Polyaniline and Gold Nanoparticles for Protein Immobilization

This study presents a screen-printed carbon electrode surface functionalization to immobilize proteins. The process involves the deposition of gold nanoparticles on the carbon electrode and subsequent surface modification to immobilize bovine serum albumin–fluorescein isothiocyanate conjugate (BSA-FITC). A combination of conducting polymer and gold nanoparticles was employed to enhance the electrode contact area and current transmission. The electrode surface morphology and properties were evaluated by scanning electron microscopy (SEM) and Raman spectroscopy, showing the porous polyaniline (PANI) film has been formed on the carbon electrode surface with the network of dendritic nanofibers. Gold nanoparticles were evenly distributed on the PANI film to form a nanocomposite material layer on the carbon electrode. The observed size of these gold nanoparticles was significantly smaller than those on the electrode without a PANI film. Additionally, the current transmission of this composite material layer has been verified by cyclic voltammetry (CV). The results show that the amplitude of the redox peak was doubled compared to the bare carbon electrode and gold nanoparticle-only deposited electrode. Moreover, the success of the process was verified by fluorescence and cyclic voltammetry. The fluorescent green color observed under the microscope indicated that BSA-FITC was on the electrode surface. The change of CV signal after each step verified the formation of a new layer on the electrode surface. These results are anticipated to play an important role in developing high-sensitivity immunosensors in the future.

AN EVALUATION OF A GOLD SURFACE FUNCTIONALIZATION PROCEDURE FOR ANTIBODY BINDING AND PROTEIN DETECTION USING 11-MERCAPTOUNDECANOIC ACID (11-MUA)

Immunosensors play an essential role in biological element recognition systems. Among the numerous types of electrodes utilized for immunosensor, gold electrodes with surface modification have attracted considerable attention and have experienced various improvements and developments due to their advantages, compromising high conductivity and chemical stability. Self-assembled monolayer (SAM) has been used as an effective approach for biomarker immobilization onto electrodes. In this study, two types of gold electrodes, namely, sputtered gold on a glass slide and screen-printed gold electrodes, were utilized to assess the performance of the proposed procedure utilizing 11-Mercaptoundecanoic acid (11-MUA). Bovine serum albumin–fluorescein isothiocyanate conjugate (BSA-FITC) and anti-albumin antibody (anti-BSA) were employed as the antigen–antibody pair. Microscope-based fluorescent, Raman spectroscopy and electrical measurements, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), were conducted to validate the success of each step in the surface functionalization process. The results showed that BSA proteins were immobilized on the modified electrode, as indicated by the fluorescent green color observed under the microscope and the changes in surface impedance recorded in Raman spectroscopy, CV and EIS signal graphs. Additionally, the influence of the 11-MUA incubation time and the protein concentration on the performance of the gold electrode surface functionalization process were investigated. The results indicate that an incubation time exceeding 24 h and a protein concentration of 5 [Formula: see text]M was found to be the most optimal conditions. The screen-printed gold electrode exhibited a slightly superior performance in comparison to the sputtered gold electrode. This work has verified the proposed gold surface functionalization process and can serve as a solid foundation for future immunosensor research studies.

Combining atomic force microscopy and fluorescence-based techniques to explore mechanical properties of naive and ischemia-affected brain regions in mice

Knowledge of the brain’s structure and function is essential for understanding processes in health and disease. Histochemical and fluorescence-based techniques have proven beneficial in characterizing brain regions and cellular compositions in pre-clinical research. Atomic force microscopy (AFM) has been introduced for mechanical tissue characterization, which may also help investigate pathophysiological aspects in disease-related models such as stroke. While combining AFM and fluorescence-based techniques, this study explored the mechanical properties of naive and ischemic brain regions in mice. Ischemia-affected regions were identified by the green signal of fluorescein isothiocyanate-conjugated albumin. A semi-automated protocol based on a brain atlas allowed regional allocations to the neocortex, striatum, thalamus, hypothalamus, hippocampus, and fiber tracts. Although AFM led to varying measurements, intra-individual analyses indicated a gradually increased tissue stiffness in the neocortex compared to subcortical areas, i.e., the striatum and fiber tracts. Regions affected by ischemia predominantly exhibited an increased tissue stiffness compared to those of the contra-lateral hemisphere, which might be related to cellular swelling. This study indicated intra-individual differences in mechanical properties among naive and ischemia-affected brain regions. The combination of AFM, semi-automated regional allocations, and fluorescence-based techniques thus qualifies for mechanical characterizations of the healthy and disease-affected brain in pre-clinical research.

Exposure to ZnO nanoparticles induced blood-milk barrier dysfunction by disrupting tight junctions and cell injury

Zinc oxide nanoparticles (ZnO-NPs) are one of the most widely used nanomaterials with excellent chemical and biological properties. However, their widespread application has led to increased risk to the natural environment and public health. A growing number of studies have shown that ZnO-NPs deposited in target organs interact with internal barriers to trigger injurious responses. The underlying mechanism of ZnO-NPs on the blood-milk barrier dysfunction remains to be understood. Our results revealed that excessive accumulation of ZnO-NPs induced histopathological injuries in the mammary gland, leading to the distribution of ZnO-NPs in the milk of lactating mice. A prominent diffusion of blood-milk barrier permeability marker, albumin-fluorescein isothiocyanate conjugate (FITC-albumin) was observed at cell-cell junction after ZnO-NPs exposure. Meanwhile, ZnO-NPs weakened the blood-milk barrier function by altering the expression of tight junction proteins. The excessive accumulation of ZnO-NPs also induced inflammatory response by activating the NF-κB and MAPK signaling pathways, leading to the dysfunctional blood-milk barrier. Furthermore, we found that ZnO-NPs led to increased iron accumulation and lipid oxidation, thus increasing oxidative injury and ferroptosis in mammary glands. These results indicated that ZnO-NPs weaken the integrity of the blood-milk barrier by directly affecting tight junctions and cellular injury in different ways.

Influence of PEGDA Molecular Weight and Concentration on the In Vitro Release of the Model Protein BSA-FITC from Photo Crosslinked Systems.

Novel 3D printing techniques enable the development of medical devices with drug delivery systems that are tailored to the patient in terms of scaffold shape and the desired pharmaceutically active substance release. Gentle curing methods such as photopolymerization are also relevant for the incorporation of potent and sensitive drugs including proteins. However, retaining the pharmaceutical functions of proteins remains challenging due to the possible crosslinking between the functional groups of proteins, and the used photopolymers such as acrylates. In this work, the in vitro release of the model protein drug, albumin-fluorescein isothiocyanate conjugate (BSA-FITC) from differently composed, photopolymerized poly(ethylene) glycol diacrylate (PEGDA), an often employed, nontoxic, easily curable resin, was investigated. Different PEGDA concentrations in water (20, 30, and 40 wt %) and their different molecular masses (4000, 10,000, and 20,000 g/mol) were used to prepare a protein carrier with photopolymerization and molding. The viscosity measurements of photomonomer solutions revealed exponentially increasing values with increasing PEGDA concentration and molecular mass. Polymerized samples showed increasing medium uptake with an increasing molecular mass and decreasing uptake with increasing PEGDA content. Therefore, the modification of the inner network resulted in the most swollen samples (20 wt %) also releasing the highest amount of incorporated BSA-FITC for all PEGDA molecular masses.

Preparation and characterization of fast dissolving ulvan microneedles for transdermal drug delivery system

Dissolving microneedles made from natural polymers recently have gained much attention as an efficient transdermal drug delivery system (TDDS). For the first time, ulvan, a sulfated polysaccharide extracted from Ulva lactuca, was applied to fabricate dissolving microneedles through a two-step casting method. The ulvan microneedles (UMNs) made from 4% ulvan solution were in a pyramidal shape with an average height of 655 μm and an aspect ratio of 2.63. The in vitro skin insertion study showed the UMNs could totally penetrate into the porcine skin to the dermis layer and rapidly dissolved as the needle height was reduced by 90.3% after post-insertion of only 2 min. The rapid dissolution of UMNs in situ thus could release the loaded model drugs of rhodamine 6G (R6G) and bovine serum albumin–fluorescein isothiocyanate conjugate (FITC-BSA) in the skin tissue. The in vitro drug release profiles through porcine skin revealed the UMNs markedly enhanced the cumulative release of FITC-BSA. In addition, the UMNs had good biocompatibility towards normal cells of HaCaT and NIH3T3. Briefly, this study demonstrates the rapidly dissolving UMNs could effectively carry the drug into skin and thus can be developed as a potential TDDS in the pharmaceutical and cosmeceutical fields.

Feasibility of mucoadhesive chitosan maleimide-coated liposomes for improved buccal delivery of a protein drug

Chitosan-maleimide (CSMHA) coated liposomes were developed for the buccal delivery of protein. Albumin–fluorescein isothiocyanate conjugate (FITC-BSA) was used as a protein replica to be loaded in the liposomes. The liposomes were formed by a thin-film hydration technique before being decorated with CSMHA. The mucoadhesive capability of the CSMHA-coated liposomes on the porcine buccal mucosa, the loading efficiency and loading capacity, drug release, permeation through buccal mucosa, protein integrity, the cytotoxicity on oral fibroblast cells, and biocompatibility were investigated. The liposome formulations were obtained with sizes of 35–166 nm. CSMHA-coated FITC-BSA-loaded liposomes remained on the buccal tissue to the highest extent. Moreover, CSMHA-coated liposomes provided the highest buccal permeation of FITC-BSA and were safe for normal gingival fibroblast cells and buccal tissue. Therefore, the CSMHA-coated liposomes may have the capability to improve protein delivery via the buccal route.

Redox Regulation of Microvascular Permeability: IL-1β Potentiation of Bradykinin-Induced Permeability Is Prevented by Simvastatin.

Antioxidant effects of statins have been implicated in the reduction in microvascular permeability and edema formation in experimental and clinical studies. Bradykinin (Bk)-induced increases in microvascular permeability are potentiated by IL-1β; however, no studies have examined the protection afforded by statins against microvascular hyperpermeability. We investigated the effects of simvastatin pretreatment on albumin–fluorescein isothiocyanate conjugate (FITC-albumin) permeability in post-capillary venules in rat cremaster muscle. Inhibition of nitric oxide synthase with L-NAME (10µM) increased basal permeability to FITC-albumin, which was abrogated by superoxide dismutase and catalase. Histamine-induced (1 µM) permeability was blocked by L-NAME but unaffected by scavenging reactive oxygen species with superoxide dismutase (SOD) and catalase. In contrast, bradykinin-induced (1–100 nM) permeability increases were unaffected by L-NAME but abrogated by SOD and catalase. Acute superfusion of the cremaster muscle with IL-1β (30 pM, 10 min) resulted in a leftward shift of the bradykinin concentration–response curve. Potentiation by IL-1β of bradykinin-induced microvascular permeability was prevented by the nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) inhibitor apocynin (1 µM). Pretreatment of rats with simvastatin (5 mg·kg−1, i.p.) 24 h before permeability measurements prevented the potentiation of bradykinin permeability responses by IL-1β, which was not reversed by inhibition of heme oxygenase-1 with tin protoporphyrin IX (SnPP). This study highlights a novel mechanism by which simvastatin prevents the potentiation of bradykinin-induced permeability by IL-1β, possibly by targeting the assembly of NADPH oxidase subunits. Our findings highlight the therapeutic potential of statins in the prevention and treatment of patients predisposed to inflammatory diseases.

Development of a 3D Printed Refillable Drug Delivery Device for Sustained Release to the Retina

Retinal degenerative diseases (RDD) such as age-related macular degeneration (AMD) and retinitis pigmentosa (RP) cause progressive loss of vision, affecting millions of people worldwide. Drug delivery system (DDS) such as vitreous injection and intraocular implant has been widely investigated to treat RDD. However, they are invasive and can risk infection of the eye. Thus, we have been working on the development of transscleral DDS, which are less invasive and can achieve more localized release of drug than the conventional methods [1]. We have previously reported capsule-type and sheet-type DDS devices that can be implanted on the transscleral (periocular) region of the eye [2] [3]. However, such devices need to be replaced once drug run out. Herein, we report a 3D printed refillable DDS device for long term delivery of drugs to the retina.The refillable device consisted of 3 sections: -polyvinyl alcohol gel chamber with openings to regulate drug release, the drug chamber as a reservoir for a test drug, and polydimethylsiloxane (PDMS) chamber with port holes to allow reinjection of the drug (Fig. 1a). The device was designed in SolidWorks 2018 (Dassault Systèmes, France) and 3D printed (Qidi Shadow 5.5S, QidiTech) using polyethylene glycol diacrylate (PEGDA) mixed with 1% photoinitiator (Irgacure819, w/w), and 1% photosensitizer (2-isopropylthioxanthone, w/w). PDMS and PVA hydrogel were manually introduced into the drug injection chamber and the drug release chamber, respectively. PDMS was cured by thermal curing and PVA was gelled by freeze-thawing. After introducing a model drug, Albumin-fluorescein isothiocyanate conjugate (FITC-Albumin), into the device, it was immersed in 5 mL of Dulbecco’s phosphate buffered saline(DPBS) and incubated at 37℃ inside a humidified incubator. The fluorescence intensities of DPBS solutions were measured by spectrofluorimetry to quantify diffusion of drugs from the capsule into the DPBS solution. The DPBS solutions were replaced at each measurement. In addition, drug reinjection and quantification of the released drug were performed. Quantification of the released drug was done by above-mentioned process.The refillable capsule-type DDS device was fabricated with a curved geometry such that it can fit the outer circumference of the eyeball (Fig. 1b). Specifically, the dimensions of the device were 20 mm inside diameter, 22 mm curvature diameter, 2 mm thickness and 4.4 mm width. By 3D printing, it was possible to fabricate a complex 3D shape that is not possible using conventional mold technique. Because the drug is impermeable to PEGDA, unidirectional release of the drug from the release ports was possible (Fig. 1c). The unidirectional release is important because it can reduce drug elimination by conjunctival clearance and increase efficiency of drug delivery. In vitro release tests of the device were performed with varying concentrations of PVA gel. The result showed that as the PVA concentration was increased, the drug release rate decreased. At 5 wt% PVA concentration, an extreme initial burst and complete release of FITC-Albumin in 7 days was observed whereas at 10 wt% PVA concentration, over 90% drug release in 30 days and complete release in 50 days were observed, and at 20 wt% PVA concentration, drug release over 100 days was observed. Similar drug release trends were observed when the drug was repeatedly injected into the same devices for 3 times. Also, no leakage of the drug from the PDMS port was confirmed during repeated injection.These in vitro experiment results show the potential of the device for future transscleral implants. As the next step, we are planning to implant the downsized device on rabbit’s eye and investigate biocompatibility and efficacy for treatment of RDD.

Magnetic nanoparticle decorated anodic alumina nanotubes for fluorescent detection of cathepsin B

In this work, we present the process to provide anodic alumina nanotubes with magnetic responsivity based on magnetic nanoparticles. We demonstrate the possibility to cause the motion of these composite nanotubes under magnetic field, providing them with guided mobility. The obtained magnetic anodic alumina nanotubes are completely characterized and their potential to undergo selective and effective functionalization, and stimuli-responsive load release is demonstrated. For this purpose, protease-triggered release of fluorescent molecules loaded inside the magnetic anodic alumina nanotubes (MAANTs) by selective functionalization is performed. The inner walls of the MAANTs were selectively covered with protein padding of albumin-fluorescein isothiocyanate conjugate (FITC-BSA) through means of silanization. Protein functionalization was designed to undergo proteolytic hydrolysis in presence of cathepsin B- protease highly expressed during growth and initial stages of tumor metastasis – in order to cleave peptide bond of albumin and release fluorescent fragments of the protein. Proteolytic reaction with the enzyme is performed under acidic conditions. Presented arrangement is an exemplary combination of functionalities – which are vast – and of value for applications like drug delivery and biosensing applications.

The Beneficial Effect of HES on Vascular Permeability and Its Relationship With Endothelial Glycocalyx and Intercellular Junction After Hemorrhagic Shock.

BackgroundVascular leakage is a common complication of hemorrhagic shock. Endothelial glycocalyx plays a crucial role in the protection of vascular endothelial barrier function. Hydroxyethyl starch (HES) is a commonly used resuscitation fluid for hemorrhagic shock. However, whether the protective effect of HES on vascular permeability after hemorrhagic shock is associated with the endothelial glycocalyx is unclear.MethodsUsing hemorrhagic shock rat model and hypoxia treated vascular endothelial cells (VECs), effects of HES (130/0.4) on pulmonary vascular permeability and the relationship to endothelial glycocalyx were observed.ResultsPulmonary vascular permeability was significantly increased after hemorrhagic shock, as evidenced by the increased permeability of pulmonary vessels to albumin-fluorescein isothiocyanate conjugate (FITC-BSA) and Evans blue, the decreased transendothelial electrical resistance of VECs and the increased transmittance of FITC-BSA. The structure of the endothelial glycocalyx was destroyed, showing a decrease in thickness. The expression of heparan sulfate, hyaluronic acid, and chondroitin sulfate, the components of the endothelial glycocalyx, was significantly decreased. HES (130/0.4) significantly improved the vascular barrier function, recovered the thickness and the expression of components of the endothelial glycocalyx by down-regulating the expression of heparinase, hyaluronidase, and neuraminidase, and meanwhile increased the expression of intercellular junction proteins ZO-1, occludin, and VE-cadherin. Degradation of endothelial glycocalyx with degrading enzyme (heparinase, hyaluronidase, and neuraminidase) abolished the beneficial effect of HES on vascular permeability, but had no significant effect on the recovery of the expression of endothelial intercellular junction proteins induced by HES (130/0.4). HES (130/0.4) decreased the expression of cleaved-caspase-3 induced by hemorrhagic shock.ConclusionsHES (130/0.4) has protective effect on vascular barrier function after hemorrgic shock.The mechanism is mainly related to the protective effect of HES on endothelial glycocalyx and intercellular junction proteins. The protective effect of HES on endothelial glycocalyx was associated with the down-regulated expression of heparinase, hyaluronidase, and neuraminidase. HES (130/0.4) had an anti-apoptotic effect in hemorrhagic shock.

Controlling the Release Profile Through Phase Control of Calcium Phosphate-Alginate Core-shell Nanoparticles in Gene Delivery

In this study, we aimed to control the drug release rate from calcium phosphate-alginate (CaP-Alg) core-shell nanoparticle (NPs) using CaP phases (brushite (DCPD) [Bru] and hydroxyapatite [HA]) generated under different pH conditions. Core-shell NPs consisted of an inorganic CaP core and an organic Alg shell and were synthesized by the water-in-oil emulsification and precipitation method. CaP-Alg NPs were synthesized under different pH conditions, resulting in the mineralization of CaP with Bru and HA in the core region of core-shell NPs. Albumin-fluorescein isothiocyanate conjugate (FITC-BSA) was used as a model drug for in-vitro drug release studies. CaP-Alg (Bru-Alg and HA-Alg) NPs exhibited a higher loading capacity and encapsulation efficiency than Ca-Alg NPs. The release behavior of synthesized core-shell NPs showed different patterns due to the pH-sensitivity of Alg and CaP. At physiological pH, Ca-Alg NPs exhibited an initial burst release behavior, while CaP-Alg showed controlled release behavior. Our results demonstrate that HA-Alg NPs are more suitable for controlled intracellular delivery while Bru-Alg NPs are more suitable for extracellular compartment delivery. Therefore, CaP-Alg NPs could be potential candidates for controlled gene and biomolecule delivery into cells for therapeutic purposes.

Sintered electrospun polycaprolactone for controlled model drug delivery

Electrospinning has been used widely for drug delivery applications due to its versatility and ease of modification of spun fiber properties. Net drug loading and release is typically limited by the inherent surface-area of the sample. In a relatively novel approach, sintering of electrospun fiber was used to create a capsule favoring long-term delivery. We showed that electrospun polycaprolactone (PCL) retained its initial morphology out to 1042 days of in vitro exposure, illustrating its potential for extended performance. Sintering decreased the electrospun pore size by 10- and 28-fold following 56 and 57 °C exposures, respectively. At 58 and 59 °C, the PCL capsules lost all apparent surface porosity, but entrapped pores were observed in the 58 °C cross-section. The use of Rhodamine B (RhB, 479.02 g mol−1), Rose Bengal (RB, 1017.64 g mol−1) and albumin-fluorescein isothiocyanate conjugate from bovine serum (BSA-FITC, ~66,000 g mol−1) as model compounds demonstrated that release (RhB > RB ≫ BSA-FITC) is controlled both by molecular weight and available porosity. Interestingly, the ranking of release following sintering was 57 > 56 > 59 > 58 °C; COMSOL simulations explored the effects of capsule wall thickness and porosity on release rate. It was hypothesized that model drug adsorption on the available fiber surface-area (57 versus 56 °C) and entrapped porosity (59 versus 58 °C) could have also attributed to the observed ranking of release rates. While the 56 and 57 °C exposures allowed the bulk of the release to occur in <1 day, the capsules sintered at 58 and 59 °C exhibited release that continued after 12 days of exposure.

Assessment of Histiotrophic Nutrition Using Fluorescent Probes.

Histiotrophic nutrition is a process whereby the rodent visceral yolk sac (VYS) internalizes exogenous macromolecules, degrades them, and sends the degradation products to the embryo. Quantification and visualization of histiotrophic nutrition can be accomplished using fluorescent tracer molecules such as fluorescein isothiocyanate-conjugated albumin (FITC-albumin). The methods are simple and can provide complimentary functional and structural information in studies of the effects of embryotoxicants on visceral yolk sac function.

A microfluidic chip with a staircase pH gradient generator, a packed column and a fraction collector for chromatofocusing of proteins.

A microfluidic device for pH gradient chromatofocusing is presented, which performs creation of a micro‐column, pH gradient generation, and fraction collection in a single device. Using a sieve micro‐valve, anion exchange particles were packed into a microchannel in order to realize a solid‐phase absorption column. To fractionate proteins according to their isoelectric points, elution buffer solutions with a stepwise pH gradient were prepared in 16 parallel mixing reactors and flowed through the micro‐column, wherein a protein mixture was previously loaded. The volume of the column is only 20 nL, hence it allows extremely low sample consumption and fast analysis compared with a conventional system. We demonstrated separation of two proteins, albumin–fluorescein isothiocyanate conjugate (FITC‐BSA) and R‐Phycoerythrin (R‐PE), by using a microcolumn of commercial charged polymeric particles (Source 15Q). The microfluidic device can be used as a rapid diagnostic tool to analyse crude mixtures of proteins or nucleic acids and determine adsorption/desorption characteristics of various biochemical products, which can be helpful for scientific fundamental understanding as well as instrumental in various industrial applications, especially in early stage screening and process development.

Modeling and closed‐loop control of particle size and initial burst of PLGA biodegradable nanoparticles for targeted drug delivery

ABSTRACTAn in‐house computer code based on artificial intelligence has been developed and applied in modeling and closed‐loop optimization of release behavior of Poly(lactic‐co‐glycolic acid) (PLGA) biodegradable particles. A series of micro‐ and nanoparticles were prepared via water‐in‐oil‐in‐water double emulsion to be loaded with albumin–fluorescein isothiocyanate conjugate as a typical drug. The interrelationship between input variables (molecular weight of polymer and stabilizer, polymer concentration, and sonication rate) and outputs (PLGA particle size and percentage of initial burst) was uncovered with the aid of artificial neural network modeling. The regression analysis confirmed acceptable correlation coefficients for the aforementioned responses, where the PLGA molecular weight played the most important role among the studied variables. Input variables needed to minimize PLGA size and PLGA initial burst were then obtained via multiobjective optimization performed by a genetic algorithm. PLGA nanoparticles were checked for particle size and particle size distribution using scanning electron micrographs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45145.

Polymer hydrogels for glutathione-mediated protein release

The use of amine-terminated poly(ethylene glycol) star polymers as macroinitiators for the N-carboxyanhydride ring-opening polymerisation of S-tert-butylmercapto-l-cysteine N-carboxahydride is described to yield amphiphilic copolymers that are capable of forming discrete particles in aqueous solution. Poly(amino acid) deprotection liberates the pendant thiol groups that can then form covalent disulfide crosslinks with adjacent thiol groups and yield a crosslinked polymer that is capable of hydrogel formation. The model protein albumin–fluorescein isothiocyanate conjugate was encapsulated within the hydrogels produced, prior to its release upon hydrogel interaction with the reducing agent glutathione. Consequently, the stimuli-responsive polymers formed hold great promise as biomaterials capable of releasing a protein molecular cargo upon interaction with glutathione.

Synthesis of catechol and zwitterion-bifunctionalized poly(ethylene glycol) for the construction of antifouling surfaces

Versatile antifouling coatings from catechol and zwitterion-bifunctionalized poly(ethylene glycol).

A Multioptimization Approach to Assessment of Drug Delivery of PLGA Nanoparticles: Simultaneous Control of Particle Size and Release Behavior

A multiple optimization strategy was implemented on the experimental data obtained in this study to assess drug-delivery behavior of poly(D,L-lactide-co-glycolide) (PLGA) particles. Albumin–fluorescein isothiocyanate conjugate (FITC-albumin)-loaded PLGA micro- and nanoparticles were prepared by water-in-oil-in-water double emulsion method. The experiments were carried out based on L8 Taguchi design where the effects of PLGA molecular weight, PLGA concentration in the oil phase, and sonication rate in the second emulsification step of preparation process on particle size and percentage of initial burst release of PLGA were discussed. Multioptimization toward PLGA particle size and initial burst elucidated that all aforementioned variables affect the characteristics of PLGA particles, but PLGA molecular weight was appeared as the most significant factor among studied variables. Multifarious optimizations were tested and executed varying the aforementioned factors to minimize both the size and percentage of initial burst of PLGA particles. The FTIR experiment of the optimal formulation showed the successful incorporation of the drug into the particles. These results enable careful selection and definition of optimal process parameters for the preparation of PLGA nanoparticles with sustained release properties. Furthermore, the methodology developed in this work introduces a useful tool to meet a drug delivery system with optimal release behavior.

Novel thermosensitive hydrogel composites based on poly(d,l‐lactide‐co‐glycolide) nanoparticles embedded in poly(n‐isopropyl acrylamide) with sustained drug‐release behavior

ABSTRACTTo reach sustained drug release, a new composite drug‐delivery system consisting of poly(d,l‐lactide‐co‐glycolide) (PLGA) nanoparticles (NPs) embedded in thermosensitive poly(N‐isopropyl acrylamide) (PNIPAAm) hydrogels was developed. The PNIPAAm hydrogels were synthesized by free‐radical polymerization and were crosslinked with poly(ethylene glycol) diacrylate, and the PLGA NPs were prepared by a water‐in‐oil‐in‐water double‐emulsion solvent‐evaporation method. The release behavior of the composite hydrogels loaded with albumin–fluorescein isothiocyanate conjugate was studied and compared with that of the drug‐loaded neat hydrogel and PLGA NPs. The results indicate that we could best control the release rate of the drug by loading it to the PLGA NPs and then embedding the whole system in the PNIPAAm hydrogels. The developed composite hydrogel systems showed near zero‐order drug‐release kinetics along with a reduction or omission of initial burst release. The differential scanning calorimetry results reveal that the lower critical solution temperature of the developed composite systems remained almost unchanged (&lt;1°C increase only). Such a characteristic indicated that the thermosensitivity of the PNIPAAm hydrogel was not distinctively affected by the addition of PLGA NPs. In conclusion, an approach was demonstrated for the successful preparation of a new hybrid hydrogel system having improved drug‐release behavior with retained thermosensitivity. The developed systems have enormous potential for many biotechnological applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40625.