Nanoencapsulation of Antioxidant-Rich Fraction of Roasted <i>Moringa oleifera</i>L. Leaf Extract: Physico-Chemical Properties and <i>in Vitro</i>Release Mechanisms

Nanocapsules (NC) of antioxidant rich fraction of roasted Moringa leaves were prepared using emulsion coacervation technique with alginate (ALG) and/or chitosan (CTS) as biopolymers. NC were characterized based on particle size, polydispersity index (PDI), zeta potential, encapsulation efficiency (EE) and loading capacity (LC). Substituting CTS with ALG in NC caused a reduction in particle size and PDI, and enhanced EE. Mean particle size dropped from 1209 nm in 1:3 to 413 nm in 3:1 ALG/CTS-NC;PDI decreased from 0.9% to 0.2% and zeta potential from -5.4 to -28.1 mV. The highest EE (87.6%) and LC (13%) were obtained with ALG-CTS-NC (3:1). ALG-NC were spherical while both CTS and ALG-CTS-NC were ovoid. ALG and ALG-CTS-NC were oil/water emulsions while CTS-NC formed water/oil emulsions. 60% and 70% of bioactives in ALG-CTS-NC (3:1) were released in simulated gastric and intestinal fluids respectively after 400 min. Release of antioxidants from NC is concentration-dependent (First order model) and involves simultaneously diffusion (Higuchi model), swelling (korsmeyer-Peppas model) and erosion (Hixson-Crowell model) mechanisms.

Preparation and evaluation of tamsulosin hydrochloride sustained-release pellets modified by two-layered membrane techniques

The aim of the present study was to develop tamsulosin hydrochloride sustained-release pellets using two-layered membrane techniques.Centrifugal granulator and fluidizedbed coater were employed to prepare drug-loaded pellets and to employ two-layered membrane coating respectively.The prepared pellets were evaluated for physicochemical characterization,subjected to differential scanning calorimetry(DSC)and in vitro release of different pH.Different release models and scanning electron microscopy(SEM)were utilized to analyze the release mechanism of Harnual■ and home-made pellets.By comparing the dissolution profiles,the ratio and coating weight gain of Eudragit■ NE30D and Eudragit■ L30D55 which constitute the inside membrane were identified as 18:1 and 10%-11%.The coating amount of outside membrane containing Eudragit■ L30D55 was determined to be 0.8%.The similarity factors(f_(2))of home-made capsule and commercially available product(Harnual■)were above 50 in different dissolution media.DSC studies confirmed that drug and excipients had good compatibility and SEM photographs showed the similarities and differences of coating surface between Harnual■ and self-made pellets before and after dissolution.According to Ritger-Peppas model,the two dosage form had different release mechanism.

Taste masking of ciprofloxacin by ion-exchange resin and sustain release at gastric-intestinal through interpenetrating polymer network

The aim of the study was to taste mask ciprofloxacin(CP)by using ion-exchange resins(IERs)followed by sustain release of CP by forming interpenetrating polymer network(IPN).IERs based on the copolymerization of acrylic acid with different cross linking agents were synthesised.Drug-resin complexes(DRCs)with three different ratios of drug to IERs(1:1,1:2,1:4)were prepared&evaluated for taste masking by following in vivo and in vitro methods.Human volunteers graded ADC 1:4,acrylic acid-divinyl benzene(ADC-3)resin as tasteless.Characterization studies such as FTIR,SEM,DSC,P-XRD differentiated ADC 1:4,from physical mixture(PM 1:4)and confirmed the formation of complex.In vitro drug release of ADC 1:4 showed complete release of CP within 60 min at simulated gastric fluid(SGF)i.e.pH 1.2.IPN beads were prepared with ADC 1:4 by using sodium alginate(AL)and sodium alginate-chitosan(AL-CS)for sustain release of CP at SGF pH and followed by simulated intestinal fluid(SIF i.e.pH 7.4).FTIR spectra confirmed the formation of IPN beads.The release of CP was sustain at SGF pH(<20%)whereas in SIF media it was more(>75%).The kinetic model of IPN beads showed the release of CP was non-Fickian diffusion type.

Studies on the PEO-PPO-PEO Block Copolymer Release from Alginate Hydrogel

IntroductionAlginate hydrogel is one of the most widely used carriers for the immobilization of micro bial cells. If surfactants are encapsulated with alginate hydrogel, increasing temperature or concentration can make the encapsulated surfactants aggregate and form micelle.

Exact solutions of two semi-infinite collinear cracks in piezoelectric strip

Using the complex variable function method and the conformal mapping technique,the fracture problem of two semi-infinite collinear cracks in a piezoelectric strip is studied under the anti-plane shear stress and the in-plane electric load on the partial crack surface.Analytic solutions of the field intensity factors and the mechanical strain energy release rate are derived under the assumption that the surfaces of the crack are electrically impermeable.The results can be reduced to the well-known solutions for a purely elastic material in the absence of an electric load.Moreover,when the distance between the two crack tips tends to infinity,analytic solutions of a semi-infinite crack in a piezoelectric strip can be obtained.Numerical examples are given to show the influence of the loaded crack length,the height of the strip,the distance between the two crack tips,and the applied mechanical/electric loads on the mechanical strain energy release rate.It is shown that the material is easier to fail when the distance between two crack tips becomes shorter,and the mechanical/electric loads have greater influence on the propagation of the left crack than those of the right one.

Molecular Mechanism of CYTOSOLIC FERRITIN Degradation and Iron release

Ferritin sequesters and stores iron and, consequently, protect cells against iron-mediated free radical damage. However, the mechanism of iron exit from the ferritin nanocage and

An experimental system for release simulation of internal stores in a supersonic wind tunnel

Aerodynamic parameters obtained from separation experiments of internal stores in a wind tunnel are significant in aircraft designs. Accurate wind tunnel tests can help to improve the release stability of the stores and in-flight safety of the aircrafts in supersonic environments.A simulative system for free drop experiments of internal stores based on a practical project is provided in this paper. The system contains a store release mechanism, a control system and an attitude measurement system. The release mechanism adopts a six-bar linkage driven by a cylinder, which ensures the release stability. The structure and initial aerodynamic parameters of the stores are also designed and adjusted. A high speed vision measurement system for high speed rolling targets is utilized to measure the pose parameters of the internal store models and an optimizing method for the coordinates of markers is presented based on a priori model. The experimental results show excellent repeatability of the system, and indicate that the position measurement precision is less than0.13 mm, and the attitude measurement precision for pitch and yaw angles is less than 0.126°, satisfying the requirements of practical wind tunnel tests. A separation experiment for the internal stores is also conducted in the FL-3 wind tunnel of China Aerodynamics Research Institute.

Are the release characteristics of Erzhi pills in line with traditional Chinese medicine theory?A quantitative study

Objective:Traditional Chinese medicine(TCM)has been widely used throughout China to prevent and cure diseases for thousands of years,and now it is a part of the integrative medicine field that is available in Western societies.To ensure the safety and quality of the herbal medicines that are a major part of the TCM tradition,they must be held to modern pharmaceutical standards.Erzhi pill(EZP)is a Chinese Pharmacopeia-listed herbal preparation that is used in the long-term clinical management of postmenopausal symptoms,osteoporosis and menstrual disorders.Until now,whether the drug release mechanism of EZP is in line with its intended TCM usage has not been studied.Methods:The release of specnuezhenide from three EZPs(self-made,Leiyunshang and Renhe)in simulated gastric fluid(SGF),acetate buffer(p H 4.5 buffer)and simulated intestinal fluid(SIF)was investigated in a dissolution test.The water uptake capacity and erosion extent of the three EZPs were investigated using swelling and erosion studies.The drug release mechanism was further assessed through statistical model fitting,using DDSolver software.Results:The release of specnuezhenide from all three EZPs in SGF was less than 50%within a 4 h period.However,over 70%of the specnuezhenide was released from each EZP in both p H 4.5 buffer and SIF in the same time.Analysis of the swelling and erosion behaviors and the drug release mechanism of the three EZPs confirmed that the release rate from EZP followed a sustained release profile,which was an interactive combination of swelling and erosion.Conclusion:This study showed that the release pattern from the pills was in line with the intended TCM use of EZP.TCM had not only theoretically considered sustained release from the pills,but also formulated them to achieve this release pattern.When establishing quality control standards for pills,the theoretical TCM usage and the actual release patterns need to be considered.

Konjac glucomannan and xanthan gum as compression coat for colonic drug delivery:experimental and theoretical evaluations

Compression coated tablets for oral colon specific delivery systems were developed with a mixture polysaccharide of konjac glucomannan(KGM)and xanthan gum(XG)as the compression coat.Diffusion of cimetidine from compression coated tablets was investigated by release experiment in Vitro.0.22U/mLβ-mannanase was applied in the mimic colon solution.The structure of the mixture polysaccharide was studied by an atomic force microscope(AFM).The experimental results indicate that a KGM70 tablet with a 0.4 g coat is of good design,due to a less than 5%drug loss in the mimic upper gastrointestinal solution by the synergistic interaction between XG and KGM,and due to about 50%cumulative release in the mimic colon solution by degradation after 24 hours.The release mechanism and model are discussed based on different periods of drug release including the delay of the drug,the constant release without an enzyme and the delay of degradation.Under hydrolysis byβ-mannanase,drug release from the tablet with KGM coat shows an exponential increase,while that from the dosage with the mixture polysaccharide coat is an approximately zero-order process in which the constant release rate relates to the release velocity of a non-degraded system,the content of KGM within the coat and the average molecular weight ratio of KGM to XG.It was found that XG was the framework of the polysaccharide mixtures by AFM,which is similar to the analysis results from experiments on drug release.

World’s first spaceflight on-orbit demonstration of a flexible solar array system based on shape memory polymer composites

With a 10%reversible compressive strain in more than 10 deformation cycles,the shape memory polymer composites(SMPCs)could be used for deployable structure and releasing mechanism.In this paper,without traditional electro-explosive devices or motors/controllers,the deployable SMPC flexible solar array system(SMPC-FSAS)is studied,developed,ground-based tested,and finally on-orbit validated.The epoxy-based SMPC is used for the rolling-out variable-stiffness beams as a structural frame as well as an actuator for the flexible blanket solar array.The releasing mechanism is primarily made of the cyanate-based SMPC,which has a high locking stiffness to withstand 50 g gravitational acceleration and a large unlocking displacement of 10 mm.The systematical mechanical and thermal qualification tests of the SMPC-FSAS flight hardware were performed,including sinusoidal sweeping vibration,shocking,acceleration,thermal equilibrium,thermal vacuum cycling,and thermal cycling test.The locking function of the SMPC releasing mechanisms was in normal when launching aboard the SJ20 Geostationary Satellite on 27 Dec.,2019.The SMPC-FSAS flight hardware successfully unlocked and deployed on 5 Jan.,2020 on geostationary orbit.The triggering signal of limit switches returned to ground at the 139 s upon heating,which indicated the successful unlocking function of SMPC releasing mechanisms.A pair of epoxy-based SMPC rolled variable-stiffness tubes,which clapped the flexible blanket solar array,slowly deployed and finally approached an approximate 100%shape recovery ratio within 60 s upon heating.The study and on-orbit successful validation of the SMPC-FSAS flight hardware could accelerate the related study and associated productions to be used for the next-generation releasing mechanisms as well as space deployable structures,such as new releasing mechanisms with low-shocking,testability and reusability,and ultra-large space deployable solar arrays.