Absorption-enhancing Effect Research Articles

Decahedral gold nanoparticles for enhancing performance of polymer solar cells

The effect of incorporating shape-controlled decahedral gold nanoparticles (NPs) of various sizes into the poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) hole transporting layer of poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl C61 butyric acid methyl ester (PC61BM)-based or poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7)/[6,6]-phenyl C71 butyric acid methyl ester (PC71BM)-based polymer solar cells (PSCs) is systematically investigated in terms of their optical properties and photovoltaic performance. It is found that the device performance is significantly influenced by the edge sizes of Au NPs. The power conversion efficiency of the P3HT:PC61BM-based PSCs, which incorporate NPs with an edge size of 43 nm, exhibits a considerable enhancement from 3.67% to 4.22% in comparison to a control cell with no NPs. In the PTB7:PC71BM-based PSC incorporating similar NPs, a similar increase from 5.92% to 6.60% is observed. The primary origin of the improved performance of the PSCs was attributed to light absorption enhancement and localized surface plasmon resonance (LSPR) effects. These results indicate the efficacy of using decahedral Au NPs in improving the performance of PSCs.

Enhanced oral delivery of alendronate by sucrose fatty acids esters in rats and their absorption-enhancing mechanisms

Oral delivery is the most fascinating route for interminable drug remedy. However, the intestinal absorption of alendronate (ALN), a bisphosphonate drug after oral administration is very poor. Absorption enhancers, which help to achieve the efficiency-safety balance, are considered one of the most promising agents for the improvement the intestinal absorption of drugs. In the current study, we focused on using sucrose fatty acid esters (SEs) as promising absorption enhancers to enhance the intestinal absorption of alendronate using an in situ closed-loop method in rats. The intestinal absorption of alendronate was significantly enhanced in the presence of SEs, especially L-1695. In addition, no considerable increase was observed in the activity of lactate dehydrogenase (LDH) or in protein release from the intestinal epithelium in the presence of sugar esters at concentrations equivalent to or lower than 1.0% (w/v), suggesting that these compounds are safe. Furthermore, mechanistic studies revealed increased membrane fluidity and loosening of the tight junctions (TJs) might be the underlying mechanism by which SEs improve the intestinal intake of alendronate, via transcellular and paracellular routes, respectively. These findings suggest that SEs are effective absorption enhancers for improving the intestinal absorption of alendronate, without causing serious damage to the enteric epithelium.

Enhanced Oral Delivery of Bisphosphonate by Novel Absorption Enhancers: Improvement of Intestinal Absorption of Alendronate by N-Acyl Amino Acids and N-Acyl Taurates and Their Absorption-Enhancing Mechanisms

Bisphosphonates (BPs) are carbon-substituted pyrophosphate analogs that exhibit a high affinity to hydroxyapatite and specifically inhibit bone resorption. Alendronate sodium (sodium 4-amino-1-hydroxybutylidene-1,1-bisphosphonate trihydrate) is a typical BP compound in clinical use. BPs have very low bioavailability, typically <1% after their oral administration, and their intestinal absorption is further reduced by co-administered drugs or food. In this study, we examined the effects of N-acyl amino acids and N-acyl taurates on the small intestinal absorption of alendronate. All N-acyl amino acids and N-acyl taurates increased the small intestinal absorption of alendronate, especially 1% (wt/vol) sodium palmitoyl sarcosinate (PN), which elicited a 14-fold increase. In addition, the absorption-enhancing effects of these enhancers were reversible and they may not cause continuous and irreversible membrane toxicity in the rat small intestine. Furthermore, we examined the absorption-promoting mechanisms of PN and found that it increased the membrane fluidity of the lipid bilayers. In addition, it was found that PN may open the tight junctions by reducing the expression level of claudin-4, which is a major tight junction protein. These findings indicate that these enhancers are useful for promoting the intestinal absorption of alendronate.

Evaluation of skin absorption of drugs from topical and transdermal formulations

The skin barrier function has been attributed to the stratum corneum and represents a major challenge in clinical practice pertaining to cutaneous administration of drugs. Despite this, a large number of bioactive compounds have been successfully administered via cutaneous administration because of advances in the design of topical and transdermal formulations. In vitro and in vivo evaluations of these novel drug delivery systems are necessary to characterize their quality and efficacy. This review covers the most well-known methods for assessing the cutaneous absorption of drugs as an auxiliary tool for pharmaceutical formulation scientists in the design of drug delivery systems. In vitro methods as skin permeation assays using Franz-type diffusion cells, cutaneous retention and tape-stripping methods to study the cutaneous penetration of drugs, and in vivo evaluations as pre-clinical pharmacokinetic studies in animal models are discussed. Alternative approaches to cutaneous microdialysis are also covered. Recent advances in research on skin absorption of drugs and the effect of skin absorption enhancers, as investigated using confocal laser scanning microscopy, Raman confocal microscopy, and attenuated total reflectance Fourier-transform infrared spectroscopy, are reviewed.

INTRANASAL MICROEMULGEL AS SURROGATE CARRIER TO ENHANCE LOW ORAL BIOAVAILABILITY OF SULPIRIDE

&lt;p&gt;&lt;strong&gt;Objective: &lt;/strong&gt;The purpose of this study is to evaluate microemulsion based gel (MBG) of sulpiride "a poorly water soluble antipsychotic with low oral bioavailability."&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;Gelling polymers such as sodium carboxymethylcellulose (CMC-Na), hydroxyl propyl methyl cellulose (HPMC K4m), carbopol 940 and Na alginate were evaluated for their potential to gel sulpiride microemulsions (MEs) without affecting the MEs structure. Also, sulpiride solution (SS) and conventional gel (without ME) were prepared and compared with MBG. Gel formulations were checked for their viscosity, pH, spreadability (S), mucoadhesive force (MF), and nasal ciliotoxicity studies. The &lt;em&gt;in vitro&lt;/em&gt; release of sulpiride across a cellophane membrane and its permeation through the nasal mucosa in phosphate buffered saline pH 6.8 (PBS) were also performed. In addition, a pharmacodynamic study of optimized formulae compared to SS and microemulsion (ME) was evaluated in rats.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;CMC-Na and HPMC K4m were not able to gel sulpiride loaded MEs while Na alginate gave an unclear gel with a sticky texture. Results revealed that the viscosity, mucoadhesion force, and spreadability of the MBG increased with increasing carbopol 940 concentrations. The flux was arranged as the following, MBG&amp;gt;conventional gel&amp;gt;sulpiride solution (SS). According to histopathological study, safe and non-irritant MBGs suitable for nasal administration were successfully prepared. Finally, the pharmacodynamic study indicated that intranasal sulpiride MBG had a significant effect (*P&amp;lt;0.001) than SS and ME administered either intravenous or intranasal.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Conclusion: &lt;/strong&gt;MBG provides significant enhancement in nasal bioavailability not only by absorption enhancing effect of ME but also, by increasing nasal residence time&lt;/p&gt;

Absorption-Enhancing Effect of Nitric Oxide on the Absorption of Hydrophobic Drugs in Rat Duodenum

Nitric oxide (NO), an endogenous gas that plays a versatile role in the physiological system, has the ability to increase the intestinal absorption of water-soluble compounds through the paracellular route. However, it remains unclear whether NO can enhance the absorption of hydrophobic drugs through the transcellular route. In this study, we examined the absorption-enhancing effect of NO on intestinal permeability of hydrophobic drugs in rat intestine. The pretreatment of rat gastrointestinal sacs with NOC7, a NO-releasing reagent, significantly increased the permeation of griseofulvin from mucosa to serosa in the sacs prepared from the duodenum, but not in those prepared from the other regions such as jejunum, ileum, and colon. The absorption-enhancing effect of NOC7 on the duodenal permeation varied depending on the hydrophobicity of the drugs used. Furthermore, NOC7 treatment was found to be apparently ineffective on the griseofulvin permeation in the duodenum pretreated with dithiothreitol (DTT) that was used as a mucus remover, even though the permeation was increased by pretreatment with DTT alone. These results suggest that NO increases the absorption of hydrophobic drugs through the transcellular route in the duodenum by modulating the mucus layer function.

Influence of Chitosan Nanoparticles as the Absorption Enhancers on Salvianolic acid B In vitro and In vivo Evaluation.

Background:Salvianolic acid B (SalB) represents the most abundant and bio-active phenolic constituent among the water-soluble compounds of Salvia miltiorrhiza. But the therapeutic potential of SalB has been significantly restricted by its poor absorption.Methods:In this study, chitosans (CS) and CS nanoparticles (NPs) with different molecular weights (MWs), which have influence on the absorption of SalB, was also investigated.Results:As a preliminary study, water-soluble CS with various MWs (3, 30, 50, and 100 kDa) was chosen. We investigated the MW-dependent Caco-2 cell layer transport phenomena in vitro of CS and NPs at concentrations (4 μg/ml, w/v). SalB, in presence CS or NPs has no significant toxic effect on Caco-2 cell. As the MW increases, the absorption enhancing effect of CS increases. However, as the MW decreases, the absorption enhancing effect of NPs increases. The AUC0–∞ of the SalB-100 kDa CS was 4.25 times greater than that of free SalB. And the AUC0–∞ of the SalB-3 kDa NPs was 16.03 times greater than that of free SalB.Conclusion:CS and NPs with different MWs as the absorption enhancers can promote the absorption of SalB. And the effect on NPs is better than CS.SUMMARY Formation mechanism for NPs

Brush border membrane vesicle and Caco-2 cell line: Two experimental models for evaluation of absorption enhancing effects of saponins, bile salts, and some synthetic surfactants.

The aim of this study was to investigate the influence of absorption enhancers in the uptake of hydrophilic compounds. The permeation of the two hydrophilic drug models gentamicin and 5 (6)-carboxyfluorescein (CF) across the brush border membrane vesicles and Caco-2 cell lines were evaluated using total saponins of Acanthophyllum squarrosum, Quillaja saponaria, sodium lauryl sulfate, sodium glycocholate, sodium taurodeoxycholate, and Tween 20 as absorption enhancers. Transepithelial electrical resistance (TEER) measurement was utilized to assess the paracellular permeability of cell lines. Confocal laser scanning microscopy (CLSM) was performed to obtain images of the distribution of CF in Caco-2 cells. These compounds were able to loosen tight junctions, thus increasing paracellular permeability. CLSM confirmed the effect of these absorption enhancers on CF transport across Caco-2 lines and increased the Caco-2 permeability via transcellular route. It was also confirmed that the decrease in TEER was transient and reversible after removal of permeation enhancers.

Development of a Transnasal Delivery System for Recombinant Human Growth Hormone (rhGH): Effects of the Concentration and Molecular Weight of Poly-L-arginine on the Nasal Absorption of rhGH in Rats.

A novel system for delivering recombinant human growth hormone (rhGH) that is noninvasive and has a simple method of administration is strongly desired to improve the compliance of children. The aim of this study was to investigate the potential for the intranasal (i.n.) co-administration of rhGH with poly-L-arginine (PLA) as a novel delivery system by evaluating the effects of the concentration and molecular weight of PLA on the nasal absorption of rhGH. The influence of the formation of insoluble aggregates and a soluble complex in the dosage formulation on nasal rhGH absorption was also evaluated by size-exclusion chromatography and ultrafiltration. PLA enhanced the nasal absorption of rhGH at each concentration and molecular weight examined. Nasal rhGH absorption increased dramatically when the PLA concentration was 1.0 % (w/v) due to the improved solubility of rhGH in the formulation. A delay in rhGH absorption was observed when the molecular weight of PLA was increased. This appeared to be because the increase in molecular weight caused the formation of a soluble complex. It seems that the PLA concentration affects the absorption-enhancing effect on rhGH, while the molecular weight of PLA affects the time when the maximum plasma rhGH concentration was reached (Tmax) of rhGH after i.n. administration, mainly because of the interactions among rhGH, PLA, and additives. Therefore, the transnasal rhGH delivery system using PLA is considered to be a promising alternative to subcutaneous (s.c.) injection if these interactions are sufficiently controlled.

Absorption-enhancing effects of gemini surfactant on the intestinal absorption of poorly absorbed hydrophilic drugs including peptide and protein drugs in rats

In general, the intestinal absorption of small hydrophilic molecules and macromolecules like peptides, after oral administration is very poor. Absorption enhancers are considered to be one of the most promising agents to enhance the intestinal absorption of drugs. In this research, we focused on a gemini surfactant, a new type of absorption enhancer. The intestinal absorption of drugs, with or without sodium dilauramidoglutamide lysine (SLG-30), a gemini surfactant, was examined by an in situ closed-loop method in rats. The intestinal absorption of 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate-dextrans (FDs) was significantly enhanced in the presence of SLG-30, such effect being reversible. Furthermore, the calcium levels in the plasma significantly decreased when calcitonin was co-administered with SLG-30, suggestive of the increased intestinal absorption of calcitonin. In addition, no significant increase in the of lactate dehydrogenase (LDH) activity or in protein release from the intestinal epithelium was observed in the presence of SLG-30, suggestive of the safety of this compound. These findings indicate that SLG-30 is an effective absorption-enhancer for improving the intestinal absorption of poorly absorbed drugs, without causing serious damage to the intestinal epithelium.

Synergistic promotion of solar-driven H2 generation by three-dimensionally ordered macroporous structured TiO2-Au-CdS ternary photocatalyst

A ternary photocatalyst TiO2-Au-CdS based on three-dimensionally ordered macroporous TiO2 (3DOM TiO2) was successfully prepared to enhance the light absorption, extend the light responsive region, reduce the recombination rate of charge carriers and promote the efficiency of water splitting H2 evolution ultimately. The obtained 3DOM TiO2-Au-CdS powder has a pure anatase phase of TiO2 and greenockite structured CdS according to the XRD results and TEM analysis. Au nanoparticles (AuNPs) and CdS were evenly distributed in the 3DOM structure which enhances H2-generation rate under visible light by improving light harvesting and utilizing its mass transfer facilitation. As a result, the hydrogen generation rate (1.81mmolh−1g−1) using 3DOM TiO2-Au-CdS photocatalyst under visible light irradiation was 13-fold higher than the binary 3DOM TiO2-CdS reference photocatalyst. Under ultraviolet-visible light, the photogenerated electrons in TiO2 would be transferred to recombine with the holes of CdS and under visible light, electrons would move to the conduction band (CB) of TiO2 from CdS via AuNPs. The two different types of internal electron-transfer process in the ternary photocatalyst under ultraviolet and visible light were proposed respectively and both would efficiently reduce the recombination rate of photogenerated electrons and holes thus stimulate H2 evolution rate. The present work demonstrated an excellent example of the synergistic effect of the light absorption enhancement by 3DOM structure, the photosensitizing and electron reservoir effect of AuNPs and the reduction of recombination rate of charge carriers by CdS to highly promote the photocatalytic activity in water splitting reaction.

Experimental investigation on enhancement of ammonia–water falling film generation by adding carbon black nanoparticles

This paper presents a falling film generating apparatus for testing the ammonia vapor generation amount and the generation rate with or without carbon black (CB) nanoparticles. The comparative experiments were based on influence of the concentrations of nanoparticles, surfactant, ammonia–water and hot water temperature. The results show that the ammonia vapor amount can be directly obtained through the test bench. The generation rate of ammonia vapor can be improved by adding the matched mass fraction of carbon black (CB) and proper volume fraction of emulsifier OP-10. For the base solution of ammonia whose mass fraction ranges from 25% to 40%, the effective generation ratio can be increased by 50% by adding 0.1% mass fraction of CB and 0.1% volume fraction of OP-10. However, only adding the dispersant OP-10 dispersants will produce a certain inhibitory effect on generating ammonia vapor. In order to achieve optimal results, the dispersion stability and whether it can play a positive effect should be taken into account. Combining with the absorption enhancement effect, we know that nanoparticles have great effects on absorption and generation process in ammonia–water absorption refrigeration systems (AARS). Therefore, adding nanoparticles with optimal dispersion stability into ammonia–water to enhance the COP of AARS should have a more promising future for their commercial application.

Improvement of pulmonary absorption of poorly absorbable macromolecules by hydroxypropyl-β-cyclodextrin grafted polyethylenimine (HP-β-CD-PEI) in rats

Effects of hydroxypropyl-β-cyclodextrin grafted polyethylenimine (HP-β-CD-PEI) including HP-β-CD-PEI600, HP-β-CD-PEI1800, HP-β-CD-PEI10000 on the pulmonary absorption of insulin, calcitonin, 5(6)-carboxyfluorescein (CF) and fluorescein isothiocyanate dextrans (FDs) with various molecular weights (FD4, FD10 and FD70) were examined by an pulmonary absorption study in rats. Pulmonary absorptions of these poorly absorbable drugs were significantly enhanced by HP-β-CD-PEI1800 and HP-β-CD-PEI10000, and HP-β-CD-PEI1800 with the concentration of 5% (w/v) provided maximal absorption enhancing effect on pulmonary absorption of these model drugs. The toxicity study demonstrated that HP-β-CD-PEI did not induce any toxic action to rat pulmonary membranes. In addition, zeta potential of insulin solution changed to positive by addition of various HP-β-CD-PEI, meanwhile, the degree of positive charge was linearly correlated with absorption enhancing effect of HP-β-CD-PEI, suggesting that positive charge of HP-β-CD-PEI might be related to their absorption enhancing mechanisms for enhancing pulmonary absorption of insulin in rats. In conclusion, HP-β-CD-PEI is a potential and safe absorption enhancer for improving absorption of hydrophilic macromolecules especially peptide and protein drugs by pulmonary delivery.

Combining Chemical Permeation Enhancers for Synergistic Effects

Currently, macromolecular drugs such as proteins are mainly administered by means of injections due to their low intestinal epithelial permeability and poor stability in the gastrointestinal tract. This study investigated binary combinations of chemical drug absorption enhancers to determine if synergistic drug absorption enhancement effects exist. Aloe vera, Aloe ferox and Aloe marlothii leaf gel materials, as well as with N-trimethyl chitosan chloride (TMC), were combined in different ratios and their effects on the transepithelial electrical resistance (TEER), as well as the transport of FITC-dextran across Caco-2 cell monolayers, were measured. The isobole method was applied to determine the type of interaction that exists between the absorption enhancers combinations. The TEER results showed synergism existed for the combinations between A. vera and A. marlothii, A. marlothii and A. ferox as well as A. vera and TMC. Antagonism interactions also occurred and can probably be explained by chemical reactions between the chemical permeation enhancers, such as complex formation. In terms of FITC-dextran transport, synergism was found for combinations between A. vera and A. marlothii, A. marlothii and A. ferox, A. vera and TMC, A. ferox and TMC and A. marlothii and TMC, whereas antagonism was observed for A. vera and A. ferox. The combinations where synergism was obtained have the potential to be used as effective drug absorption enhancers at lower concentrations compared to the single components.

Quantitative x-ray spectrometric analysis with peak to Compton ratios

Abstract Standardization with the scattered x-rays compensates several phenomenons as absorption-enhancement effects, particle size, surface texture effects, packing density and some instrument error. In this work, we used the scattered peak ratio method for quantitative analysis. The samples were prepared from PbO and HgO powders. The calibration curves were created from the intensity ratios of I c o h / I C o m p , I L β / I C o m p , I K α 1 / I C o m p and I K α 2 / I C o m p , one for PbO sample and the other for HgO sample, versus concentration in EDXRF (energy dispersive x-ray fluorescence) system. PbO and HgO targets of various concentrations were excited by 59.54 keV γ-rays from a 5 Ci 241Am annular radioactive source in EDXRF system. The emitted and scattered x-rays by samples were counted by an HPGe detector with a resolution of 182 eV at 5.9 keV at a scattering angle of 168°. Also, WDXRF (wavelength dispersive x-ray fluorescence) system was used to compare the concentrations determined by using EDXRF system. It can conclude that the peak to Compton ratio is highly reliable for quantitative analysis and the calculated concentrations are in good agreement with the EDXRF and WDXRF results. This work is important because PbO and HgO are used extensively as shielding material and catalyst in the chemical reactions.

Absorption-improving effects of chitosan oligomers based on their mucoadhesive properties: a comparative study on the oral and pulmonary delivery of calcitonin

Effects of chitosan oligomers with different types and varying concentrations on the intestinal and pulmonary absorptions of calcitonin were investigated in rats by an in situ closed loop method and an in vivo pulmonary absorption experiment, respectively. Various chitosan oligomers demonstrated different efficiencies in improving the intestinal and pulmonary absorptions of calcitonin, and chitosan hexamer with the optimal concentration of 0.5% (w/v) showed the greatest absorption enhancing effect. Moreover, pharmacodynamic parameters of calcitonin after its coadministration intrapulmonarily with various chitosan oligomers were consistently larger than that in the intestinal delivery, indicating the superior potential of pulmonary administration for systemic delivery of calcitonin. Furthermore, various chitosan oligomers neither obviously increased release amounts of protein nor activities of lactate dehydrogenase (LDH) in bronchoalveolar lavage fluid (BALF), revealing the safety of these chitosan oligomers to lung tissue. In addition, bioadhesions of various chitosan oligomers were well consistent with their absorption enhancing effects in the absorption experiment, suggesting the contribution of mucoadhesive properties of chitosan oligomers to their absorption improving effects. Taken together, chitosan oligomers, especially chitosan hexamer, can effectively improve the intestinal and pulmonary absorptions of calcitonin partly due to the mucoadhesion between positive chitosan oligomers and negative mucus in the membrane.

Thiolated nanocarriers for oral delivery of hydrophilic macromolecular drugs.

It was the aim of this study to investigate the effect of unmodified as well as thiolated anionic poly(acrylic acid) (PAA) and cationic chitosan (CS) utilized in free-soluble form and as nanoparticulate system on the absorption of the hydrophilic compound FD4 across intestinal epithelial cell layer with and without a mucus layer. Modifications of these polymers were achieved by conjugation with cysteine to PAA (PAA-Cys) and thioglycolic acid to CS (CS-TGA). Particles were prepared via ionic gelation and characterized based on their amount of thiol groups, particle size and zeta potential. Effects on the cell layer concerning absorption enhancement, transepithelial electrical resistance (TEER) and cytotoxicity were investigated. Permeation enhancement was evaluated with respect to in vitro transport of FD4 across Caco-2 cells, while mucoadhesion was indirectly examined in terms of adsorption behaviour when cells were covered with a mucus layer. Lyophilized particles displayed around 1000 μmol/g of free thiol groups, particle sizes of less than 300 nm and a zeta potential of 18 mV (CS-TGA) and -14 mV (PAA-Cys). Cytotoxicity studies confirmed that all polymer samples were used at nontoxic concentrations (0.5% m/v). Permeation studies revealed that all thiolated formulations had pronounced effects on the paracellular permeability of mucus-free Caco-2 layers and enhanced the permeation of FD4 3.0- to 5.3-fold. Moreover, polymers administered as particles showed a higher permeation enhancement than their corresponding solutions. However, the absorption-enhancing effect of each thiolated formulation was significantly (p<0.05) reduced when cells were covered with mucus layer. In addition, all formulations were able to decrease the TEER of the cell layer significantly (p<0.05). Therefore, both thiolated polymers as nanoparticulate delivery systems represent a promising tool for the oral administration of hydrophilic macromolecules.

Improvement of pulmonary absorptions of poorly absorbable drugs using Gelucire 44/14 as an absorption enhancer.

This study aims to evaluate the absorption-enhancing effects of Gelucire 44/14 on the pulmonary absorption of different poorly absorbable drugs and relative mechanism of action. Absorption-enhancing effect of Gelucire 44/14 were examined by an in-vivo pulmonary absorption experiment in rats, and the membrane toxicity of Gelucire 44/14 was evaluated by measuring levels of protein and dehydrogenase (LDH) in the bronchoalveolar lavage fluid (BALF) and morphological observation. Pulmonary absorptions of fluorescein isothiocyanate-dextrans, insulin and calcitonin were enhanced by Gelucire 44/14 (0.1-2.0%, w/v) in a concentration-dependent manner, and the maximal absorption-enhancing effect was obtained when the concentration of Gelucire 44/14 increased to 2.0% (w/v). Furthermore, Gelucire 44/14 neither increase the levels of protein and LDH in BALF nor change morphology of lung compared with control group. In addition, a well correlation between the absorption-enhancing effect and surface tension of insulin solution in the presence of Gelucire 44/14 was observed, suggesting Gelucire 44/14-mediated decrease in the surface tension of the gas-liquid interface in alveolar tissue was possible one of the improving mechanisms of Gelucire 44/14. Gelucire 44/14 was a potential and safe absorption enhancer for improving the absorption of poorly absorbable drugs including insulin and calcitonin by pulmonary delivery.

Effect of chito-oligosaccharide on the intestinal absorptions of phenylethanoid glycosides in Fructus Forsythiae extract

Phenylethanoid glycosides, the main active ingredients in Fructus Forsythiae extract possesses strong antibacterial, antioxidant and antiviral effects, and their contents were higher largely than that of other ingredients such as lignans and flavones, but their absolute bioavailability orally was significantly low, which influenced clinical efficacies of its oral preparations seriously. In the present study, the absorption mechanism of phenylethanoid glycosides was studied using in vitro Caco-2 cell model. And the effect of chito-oligosaccharide (COS) on the intestinal absorption of phenylethanoid glycosides in Fructus Forsythiae extract was investigated using in vitro, in situ and in vivo models. The pharmacological effects such as antiviral activity improvement by COS were verified by MDCK cell damage inhibition rate after influenza virus propagation. The observations from in vitro Caco-2 cell showed that the absorption of phenylethanoid glycosides in Fructus Forsythiae extract so with that in monomers was mainly restricted by the tight junctions, and influenced by efflux transporters (P-gp and MRP2). Meanwhile, the absorption of phenylethanoid glycosides in Fructus Forsythiae extract could be improved by COS. Besides, COS at the same low, medium and high concentrations caused a significant, concentration-dependent increase in the Papp-value for phenylethanoid glycosides compared to the control group (p<0.05), and was all safe for the Caco-2 cells. The observations from single-pass intestinal perfusion in situ model showed that the intestinal absorption of phenylethanoid glycosides can be enhanced by COS. Meanwhile, the absorption enhancing effect of phenylethanoid glycosides might be saturable in different intestine sites. In pharmacokinetics study, COS at dosage of 25mg/kg improved the bioavailability of phenylethanoid glycosides in Fructus Forsythiae extract to the greatest extent, and was safe for gastrointestine from morphological observation. In addition, treatment with Fructus Forsythiae extract with COS at dosage of 25mg/kg prevented MDCK cell damage upon influenza virus propagation better than that of control. All findings above suggested that COS at dosage of 25mg/kg might be safe and effective absorption enhancer for improving the bioavailability of phenylethanoid glycosides and the antiviral activity in vitro in Fructus Forsythiae extract.

Experimental study of CO2 absorption in aqueous MEA and MDEA solutions enhanced by nanoparticles

The nanofluids based on MEA and MDEA solutions were prepared using ultrasonic dispersion method without any surfactant addition to study the influence of nanoparticles on the CO2 absorption by MEA and MDEA in the bubbling reactor. The influences of various factors including solid loading of nanoparticles, nanoparticle size, nanoparticle type, total volume flow rate of mixed gas and initial CO2 volume fraction on the CO2 absorption were investigated. Although the reaction rates of MEA-CO2 and MDEA-CO2 were different, the findings about the influence of nanoparticles based on MDEA solution were similar to that based on MEA solution. Most of tested nanoparticles could remarkably improve the gas–liquid mass transfer during the CO2 absorption process. The CO2 absorption enhancement factor increased with the increase of the solid loading of nanoparticles up to a maximum value and then decreased. The CO2 absorption enhancement factor based on the MEA solution for larger nanoparticles was greater than that for smaller nanoparticles. On the other hand, the absorption enhancement effect of nanoparticles based on the MDEA solution depends highly on the type of nanoparticle. It is also found that the enhancement factor based on the MDEA solution increased with the increase of the total volume flow rate of mixed gas or the initial CO2 volume fraction.