The combined use of carbon nanotubes with synthetic ceramics enhances posterolateral fusion: an experimental study in a rat spinal fusion model.

PURPOSE: The aim of the present study was to evaluate the effectiveness of carbon nanotubes (CNTs)/ HA-tricalcium phosphate (TCP) composite in a posterolateral spinal fusion model. METHODS: At first, CNTs and CNTs/HA-TCP composites were prepared. Twenty adult male Sprague Dawley rats were randomized into four groups with five rats in each group. Decortication was carried out in standard manner in all animals. Group 1 (only decortication), group 2 (CNTs), group 3 (HA-TCP) and group 4 (CNTs/HA-TCP) were formed. Eight weeks later, all animals were killed and obtained fusion segments were evaluated by manual palpation, histomorphometry and micro-computed tomography (mCT). RESULTS: In all evaluations, highest fusion values were obtained in Group 4. In mCT investigations, bone volume/ tissue volume (BV/TV) ratio was found to be significantly higher in composite group (group 4) only compared to ceramic group (group 3) (p < 0.001). Although in Group 2, in which only CNTs were used, the ratio was found to be statistically significantly higher than group 1(p < 0.001), the difference was not considered as significant in terms of fusion and in addition in group 2, CNTs were completely surrounded by fibrous tissue, i.e., no bone formation was observed. CONCLUSIONS: The CNTs/HA-TCP composite is a promising synthetic bone graft substitute for spinal fusion. Although CNTs are inadequate in producing spinal fusion when they are used alone, due to their high biocompatibility due to their high biocompatibility, and multiple effect on bone regeneration, they seem to increase fusion rates significantly when they are used in combination with ceramic-based synthetic grafts.

Effect of different molecular weight and terminal group PLGA on docetaxel nanoparticles: characterization and cytotoxic activity of castration-resistant prostate cancer cells.

The choice of polymer and its compatibility with drug used determine the fate of nanoparticle in therapy. There has been limited sources about effect of resomer differentiation in nanoparticle related with physical and chemical properties and also biological activities of product. Therefore, we aimed to formulate docetaxel-loaded polylactic-co-glycolic acid nanoparticles with different molecular weights (Resomer 502 and 504) and terminal groups (Resomer 502H and 504H) and to investigate the effect of these resomers on nanoparticle character, prostate cancer, and healthy cells. Docetaxel-loaded PLGA nanoparticles were prepared by single emulsion solvent evaporation method. Surface characterizations were carried out by zeta sizer and scanning electron microscopy. Encapsulation efficiency, in vitro drug release profiles, and cytotoxic activity were determined. Main effect on the surface morphology of nanoparticles was the molecular weight of the polymer. The groups with acid terminal function have higher encapsulation and reaction efficiency. In all formulations, in vitro release was observed after 334 h at pH 7.4 and 240 h at pH 5.6. Also, the groups with high molecular weight showed selective cytotoxicity. These resomers especially RG 504 and RG 504H have potential to be used as a low-dose and high-efficiency extended-release drug delivery system in the treatment of prostate cancer.

Enhanced Dermal Delivery of Flurbiprofen Nanosuspension Based Gel: Development and Ex Vivo Permeation, Pharmacokinetic Evaluations.

PURPOSE: The objective of this study was to optimize the Flurbiprofen (FB) nanosuspension (NS) based gel and to investigate the in vitro release, ex vivo permeation, the plasma concentration-time profile and pharmacokinetic parameters. METHODS: FB-NSs were developed using the wet milling process with the Design of Experiment (DoE) approach. The optimum FB-NS was characterized on the basis of SEM, DSC, XRPD, solubility and permeation studies. The dermal gel was prepared by incorporating FB-NS into HPMC gel. Then the in-vitro release, ex vivo permeation studies were performed, and pharmacokinetic studies were evaluated on rats. RESULTS: The particle size, polydispersity index and zeta potential values of optimum NS were determined as 237.7 ± 6.8 nm, 0.133 ± 0.030 and - 30.4 ± 0.7 mV, respectively. By means of the surfactant content and nanosized particles of the nanosuspension, the solubility of FB was increased about 7-fold. The percentage permeated amount of FB from FB-NS gel (8.40%) was also found to be higher than the physical mixture (5.25%) and coarse suspension (reference) (2.08%) gels. The pharmacokinetic studies showed that the Cmax of FB-NS gel was 2.5 times higher than the reference gel, while AUC0-24 was 2.96 times higher. CONCLUSION: FB-NSs were successfully prepared with a wet milling method and optimized with the DoE approach. The optimized FB nanosuspension gel provided better permeation and pharmacokinetic performance compared to FB coarse suspension gel.

Preparation and in vitro / in vivo evaluation of flurbiprofen nanosuspension-based gel for dermal application.

Flurbiprofen (FB) is an analgesic and anti-inflammatory drug, but its low water solubility (BCS Class II) limits its dermal bioavailability. The aim of this study is to develop a FB nanosuspension (NS) based gel and to evaluate its analgesic and anti-inflammatory activities in rats. FB-NS was produced by the wet milling method with Plantacare 2000Ⓡ, as stabilizer. The FB-NS was then incorporated in different carrier gels such as hydroxypropyl methyl cellulose (HPMC), polycarbophil, oleogel, and chitosan. To select the optimum gel type, visual examinations, pH and rheological property measurements, texture profile analysis, in vitro release and ex vivo permeation studies were performed. Following these tests, the analgesic and anti-inflammatory activities of the optimum NS based gel were evaluated using the tail flick and carrageenan-induced paw edema methods consecutively. The NS was successfully prepared with the wet milling method, and the PS, PDI and ZP values were found to be 237.7 ± 6.8 nm, 0.133±0.030, and -30.4 ± 0.7 mV; respectively. Among the NS-based gels, HPMC gel showed more suitable rheological and mechanical properties, also the percentage of permeated FB and the flux value observed for HPMC gel were higher for HPMC than for the other gels. Thus, HPMC gel was selected as a carrier gel for in vivo pharmacodynamics studies. The anti-inflammatory activity of FB-NS HPMC gel was higher than that of the physical mixture gel and that of the coarse suspension gel. Results of our analgesic activity studies showed that, in the 180th min of FB nanosuspension treatment, the latency time was significantly prolonged compared to that of the control group (p<0.05). As a conclusion, while nanosuspensions increased the in vivo pharmacodynamics effect of FB by means of nanosized particles and a large surface area, the HPMC gel as a carrier prolonged the contact time of NSs with skin and eased the dermal application.

Antitumor activity of gemcitabine hydrochloride loaded lipid polymer hybrid nanoparticles (LPHNs): In vitro and in vivo.

The present study demonstrated the application of gemcitabine hydrochloride (GEM) loaded lipid polymer hybrid nanoparticles (LPHNs) for the enhancement the chemotherapeutic response. GEM, which is an anti-tumor drug, is frequently utilized for the treatment of non-small cell lung cancer, breast cancer and pancreatic cancer. GEM loaded LPHNs were formed and examined for pharmacokinetic profile and in vivo anticancer activity. Modified double emulsion solvent evaporation method was employed in the preparation of the LPHNs. Cytotoxicities of the GEM loaded LPHNs formulation were evaluated on MCF-7 and MDA-MB-231 cells by MTT assays. Pharmacokinetics and in vivo anticancer efficacy studies were conducted following intraperitoneal administration in female Sprague-Dawley rats. In vivo pharmacokinetic studies in rats exhibited the advantage of the GEM loaded LPHNs over commercial product Gemko® and the GEM loaded LPHNs had longer circulation time. The half-life of GEM in LPHNs formulation was notable advanced (4.2 folds) comparing to commercial product of GEM (native). These findings indicated that GEM loaded LPHNs can be used for enhancing antitumor efficacy for breast cancer treatment.

The effect of critical process parameters of the high pressure homogenization technique on the critical quality attributes of flurbiprofen nanosuspensions.

Flurbiprofen (FB) is an effective nonsteroidal anti-inflammatory and BCS class II drug and its poor solubility plays a critical role in limiting its bioavailability. Nanosuspensions can be defined as nanosized colloidal dispersions of drug particles stabilized with stabilizers. The solubility of poor soluble drugs can be increased thanks to their small size and large surface area. The aim of this study is to optimize FB nanosuspensions. The formulations were stabilized with Plantacare 2000® as a surfactant using a combination of High Speed Homogenization (HSH) and High Pressure Homogenization techniques (HPH). We also investigated the effects of the critical process parameters (CPPs) of these techniques (homogenization speed & time for HSH and homogenization pressure & cycle for HPH) on three critical quality attributes of nanosuspensions, being the particle size (PS), polydispersity index (PDI) and zeta potential (ZP). After the optimization of HSH, the macrosuspension was transferred to a high pressure homogenizer. After producing FB nanosuspensions by the HPH technique, seven processes which comprise different homogenization pressures, or combinations and different cycles, were applied. Due to the combination of HSH and HPH techniques and the optimization of CPPs, an optimum formulation for a dermal application was found using a 33 full factorial design with these process parameters, and characterization studies were also performed.

Dermal flurbiprofen nanosuspensions: Optimization with design of experiment approach and in vitro evaluation.

Flurbiprofen (FB) is the one of the non-steroidal anti-inflammatory drugs (NSAIDs) which has low water solubility and dissolution. Nanosuspensions are promising drug delivery systems consisting pure drug particles to overcome poor water solubility issues. Recently, design of experiment (DoE) approaches have often been used to develop new formulations include nanosuspensions. The main objective of this study was to prepare FB nanosuspensions in existence of Plantacare 2000 (PL) as stabilizer using DoE approach to evaluate the critical formulation attributes (CFAs) and critical process parameters (CPPs). Particle size, particle size distribution and zeta potential values were selected as dependent variables and FB%, FB: PL and homogenization cycles were independent variables. Both 23 and 33 factorial designs were used to achieve optimum nanosuspension formulation. The final nanosuspension was freeze-dried and then crystalline state, morphological and thermal properties were investigated using X-ray diffraction, scanning electron microscopy and differential scanning calorimetry, respectively. The saturation solubility studies of nanosuspensions were conducted in comparison with the coarse powder and the physical mixture. The in vitro permeation of nanosuspension and FB solution were determined through dialysis membrane and rat skin. The particle size, polydispersity index and zeta potential values were found to range 665 nm-700 nm, 0.200-0.300 and approximately -30 mV, respectively. Nanosuspensions were obtained with spherical shape and no polymorphic or crystalline state change were observed. The saturation solubility of FB was 5.3 fold increased in nanosuspension formulation. Permeability of FB nanosuspension was higher than FB solution in rat skin. It was concluded that the DoE approach is a useful tool to prepare FB nanosuspensions and nanosuspensions benefit to improve water solubility and dermal permeation of Biopharmaceutical Classification System (BCS) Class II drugs.

Development and characterization of gemcitabine hydrochloride loaded lipid polymer hybrid nanoparticles (LPHNs) using central composite design.

Lipid polymer hybrid nanoparticles (LPHNs) combine the characteristics and beneficial properties of both polymeric nanoparticles and liposomes. The objective of this study was to design and optimize gemcitabine hydrochloride loaded LPHNs based on the central composite design approach. PLGA 50:50/PLGA 65:35 mass ratio (w/w), soya phosphatidylcholine (SPC)/polymer mass ratio (%, w/w) and amount of DSPE-PEG were chosen as the investigated independent variables. The LPHNs were prepared with modified double emulsion solvent evaporation method and characterized by testing their particle size, encapsulation efficiency, and cumulative release. The composition of optimal formulation was determined as 1,5 (w/w) PLGA 50:50/PLGA 65:35 mass ratio, 30% (w/w) SPC/polymer mass ratio and 15 mg DSPE-PEG. The results showed that the optimal formulation gemcitabine hydrochloride loaded LPHNs had encapsulation efficiency of 45,2%, particle size of 237 nm and cumulative release of 62,3% at the end of 24 h. The morphology of LPHNs was found to be spherical by transmission electron microscopy (TEM) observation. Stability studies showed that LPHNs were physically stable until 12 months at 4 °C and 9 months at 25 °C/60% RH. The results suggest that the LPHNs can be an effective drug delivery system for hydrophilic active pharmaceutical ingredient.

Quantification and spatial distribution of salicylic acid in film tablets using FT-Raman mapping with multivariate curve resolution.

In this study, we proposed a rapid and sensitive method for quantification and spatial distribution of salicylic acid in film tablets using FT-Raman spectroscopy with multivariate curve resolution (MCR). For this purpose, the constituents of film tablets were identified by using FT-Raman spectroscopy, and then eight different concentrations of salicylic acid tablets were visualized by Raman mapping. MCR was applied to mapping data to expose the active pharmaceutical ingredients in the presence of other excipients by monitoring distribution maps and combination of FT-Raman mapping with MCR enabled the determination of lower salicylic acid concentrations. In addition, the distribution of major excipient, lactose, was examined in the tablet form. A calibration curve was obtained by plotting the intensity of the Raman signal at 1635 cm-1 versus the concentration of salicylic acid and the correlation was found to be linear within the range of 0.5%-3.9% with a correlation coefficient of 0.99. The limit of detection for the technique was determined 0.35%. The ability of the technique to quantify salicylic acid in tablet test samples was also investigated.

Gemcitabine hydrochloride-loaded liposomes and nanoparticles: comparison of encapsulation efficiency, drug release, particle size, and cytotoxicity.

The aim of this study is to formulate and compare the physicochemical properties of negatively charged liposomes and poly(lactide-co-glycolide) (PLGA) nanoparticles loaded with gemcitabine hydrochloride. The influence of the formulation variables on the liposome and nanoparticle properties on particle size, zeta potential, encapsulation efficiency, and drug release was evaluated. Although the PEGylated nanoparticles and PEGylated liposomes were of the same size (∼200 nm), the encapsulation efficiency was 1.4 times higher for PEGylated liposomes than for PEGylated nanoparticles. The optimized formulation of PEGylated liposomes and PEGylated nanoparticles had 26.1 ± 0.18 and 18.8 ± 1.52% encapsulation efficiency, respectively. The release of drug from the PEGylated liposomes and PEGylated nanoparticles exhibited a biphasic pattern that was characterized by a fast initial release during the first 2 h followed by a slower continuous release. Transmission electron microscopy (TEM) images identified separate circular structures of the liposomes and nanoparticles. The in vitro cytotoxicity of the optimized formulations was assessed in MCF-7 and MDA-MB-231 cells, and the results showed that the cytotoxicity effect of the gemcitabine hydrochloride-loaded liposomes and nanoparticles was more than commercial product Gemko® and gemcitabine hydrochloride solution.

Multiwalled Carbon Nanotube-Chitosan Scaffold: Cytotoxic, Apoptoti c, and Necrotic Effects on Chondrocyte Cell Lines.

BACKGROUND: Carbon nanotubes (CNTs) have been considered highly successful and proficient in terms of their mechanical, thermal and electrical functionalization and biocompatibility. In regards to their significant extent in bone regeneration, it has been determined that CNTs hold the capability to endure clinical applications through bone tissue engineering and orthopedic procedures. In the present study, we report on a composite preparation, involving the use of CNT-chitosan as scaffold for bone repair and regeneration. Through the use of water-soluble tetrazolium salt (WST-1) and double staining methods, the cytotoxic, necrotic, and apoptotic effects of chitosan-multiwalled carbon nanotube nanocomposites on the chondrocyte ATTC cell line have been exhibited. METHODS: The chitosan-multiwalled carbon nanotube scaffolds were prepared. Chondrocytes differentiation tool (ATCC) cell line was prepared. WST-1 assay for cytotoxicity studies were performed by using chondrocytes cells in 12.5-200 µL concentration range. The samples of membranes (chitosan- multiwalled carbon nanotube scaffold) were measured at 2 mg/mL and further prepared amongst chitosan- multiwalled carbon nanotube scaffold's which were placed into separate wells. While in the process of incubation, in the four-hour time range, the plates were immediately read in an Elisa microplate Reader. To predict the number of apoptotic and necrotic cells in culture, the technique of double staining with Hoechst dye was performed with PI on the basis of scoring cell nuclei. The mechanical properties such as tensile strength and elongation at break values of the chitosan only and chitosan/CNT scaffolds were evaluated on Texture Analyzer. RESULTS: Based on the results of the WST-1 assay procedure, the amount of cell viability was not significantly affected by nanocomposite concentrations and the lowest mortality rate of cells was obtained at a concentration of 12.5 µg/mL, whereas the highest mortality rate was obtained at a rate of 200 µg/mL. In addition, the effects of chitosan-CNT nanocomposites were not found to cytotoxic on chondrocyte cells. The double staining method has been able to determine the apoptotic and necrotic effects of chitosan MWCNT nanocomposites. The apoptotic and necrotic effects of the combined compounds had varied within the concentrations. In a similar manner to the outcome of the control groups, apoptosis was obtained at a percentage of 2.67%. Under a fluorescent inverted microscope, the apoptotic cell nuclei were stained with a stronger blue fluorescence in comparison to non-apoptotic cells, which may have had an effect. We also compared the strain-stress curve measurements results. The results indicated that the mechanical properties of scaffold were not different. Elongation at break values increased by addition of CNT. CONCLUSION: CNTs as a biomaterial hold the potential to be used for applications in future regenerative medicine. By using the components of chondrocytes (ATTC) cell lines, the cytotoxicity evaluations were made for the chitosan-multiwalled carbon nanotube scaffold. The chitosan-MWCNT nanocomposites do not seem to induce drastic cytotoxicity to the chondrocyte cells.

Development and Validation of an Ultra Performance Liquid Chromatography Method for the Determination of Dexketoprofen Trometamol, Salicylic Acid and Diclofenac Sodium.

OBJECTIVES: A simple, fast, accurate and precise method has been developed for the determination of dexketoprofen trometamol (DKP), salicylic acid (SA) and diclofenac sodium (DIC) in the drug solutions using ultra high performance liquid chromatography (UPLC). MATERIALS AND METHODS: UPLC method is highly reliable and sensitive method to quantify the amount of the active ingredient and the method is validated according to ICH guidelines. RESULTS: The developed method is found to be precise, accurate, specific and selective. The method was also found to be linear and reproducible. The value of limit of dedection (LOD) of DKP, SA, DIC were found 0.00325 µg/mL, 0.0027 µg/mL and 0.0304 µg/mL, respectively. The limit of quantitation (LOQ) of DKP, SA and DIC were found 0.00985 µg/mL, 0.0081 µg/mL and 0.0920 µg/mL, respectively. CONCLUSION: Proposed methods can be successfully applicable to the pharmaceutical preparation containing the above mentioned drugs (dexketoprofen trometamol, salicylic acid and diclofenac sodium). Even very small amounts of active substance can be analyzed and validations can be performed easily.

Carbon nanotube membranes to predict skin permeability of compounds.

In the present study, carbon nanotube (CNT) membranes were prepared to predict skin penetration properties of compounds. A series of penetration experiments using Franz diffusion cells were performed with 16 different membrane compositions for model chemicals. Similar experiments were also carried out with same model molecules using five different commercially available synthetic membranes and human skins for the comparison. Model chemicals were selected as diclofenac, dexketoprofen and salicylic acid. Their permeability coefficients and flux values were calculated. Correlations between permeability values of model compounds for human skins and developed model membranes were investigated. Good correlations were obtained for CNT membrane, isopropyl myristate-treated CNT membrane (IM-CNT membrane) and bovine serum albumin-cholesterol, dipalmitoyl phosphatidyl choline-treated membrane (BSA-Cholesterol-DPPC-IM-CNT membrane). An artificial neural network (ANN) model was developed using some molecular properties and penetration coefficients from pristine CNT membranes to predict skin permeability values and quite good predictions were made.

Stimuli-responsive lipid nanotubes in gel formulations for the delivery of doxorubicin.

Lipid nanotubes (LNTs) are one of the most advantageous structures for drug delivery and targeting. LNTs formed by a specially designed molecule called AQUA (AQ-NH-(CH2)10COOH (AQ: anthraquinone group) is used for drug delivery, and doxorubicin (DOX) is the drug selected. DOX and AQUA have some similarities in their molecular structures, so a significant amount of DOX can be loaded to LNTs. The AQUA LNTs are pH responsive, and drug loading increased almost linearly by increasing the pH, reaching a maximum value (96%) at pH 9.0. In terms of drug release, lower pHs are preferred. Drug-loaded LNTs are also mixed with four different gels (chitosan, alginate, hydroxypropyl methylcellulose and polycarbophil) to use the advantages of these gels. The drug release efficiency is studied using a Franz diffusion cell in which sheep colon membranes and dialysis membranes are utilized. The amount of released DOX from the chitosan gel formulations was quite high. Sodium alginate gels had lower release and slower diffusion of DOX. The cytotoxic effect of DOX-loaded AQUA LNTs has also been determined on cell cultures. Our new lipid nanotubes are a non-toxic, effective, biodegradable, biocompatible, stable and promising system for drug delivery and can be used for colonic administration of DOX for the treatment of colorectal cancer (CRC).

Complement activation by PEG-functionalized multi-walled carbon nanotubes is independent of PEG molecular mass and surface density.

Carboxylated (4%) multi-walled carbon nanotubes were covalently functionalized with poly(ethylene glycol)1000 (PEG1000), PEG1500 and PEG4000 with a PEG loading of approximately 11% in all cases. PEG loading generated non-uniform and heterogeneous higher surface structures and increased nanotube width considerably, but all PEGylated nanotube species activated the complement system in human serum equally. Increased PEG loading, through adsorption of methoxyPEG2000(or 5000)-phospholipid conjugates, generated fewer complement activation products; however, complement activation was never completely eliminated. Our observations address the difficulty in making carbon nanotubes more compatible with innate immunity through covalent PEG functionalization as well as double PEGylation strategies. FROM THE CLINICAL EDITOR: Complement-mediated toxicity is a major limiting factor in certain nanomedicine applications. This study clarifies that PEGylation of carbon nanotubes is unlikely to address this complication.

A feasible way to use carbon nanotubes to deliver drug molecules: transdermal application.

INTRODUCTION: Nanotechnology has gained increasing importance in the pharmaceutical and medical fields, beyond its importance in physics and technology. Targeting of the drug or active molecules can be achieved rather easily with some nanocarriers because of their unique properties; to program or control of delivery can also be possible. One of the smart nanosystems is carbon nanotubes (CNTs) because they are elecroconductive and they have very big surface area to deliver active molecules. There have been many drug delivery systems proposed to the scientific world using CNTs. One administration way which appears to be the most appropriate for drug delivery is transdermal application. AREAS COVERED: Performed experiments and proposed techniques with the use of CNTs are scrutinized and discussed in this review. EXPERT OPINION: In the light of current knowledge, a feasible way to use CNTs to deliver drug molecules is transdermally.

Carbon nanotubes to deliver drug molecules.

Nanotechnology is rapidly developing field in especially engineering and medical sciences. Carbon nanotubes are one of the most studied nanomaterials in material sciences and physics. Although there are limitted number of studies have been performed with carbon nanotubes in medical sciences and pharmacy, to use carbon nanotubes as drug delivery material is still at beginning and at developing stage. Carbon nanotubes are adsorptive materials and they can actively adsorb drug molecules on the surface. In this study the adsorption properties of carbon nanotubes were investigated for ibuprofen, naproxen, oxaliplatin and paclitaxel. Desorption properties and the posibility of using them as drug delivery systems for mentioned drugs were investigated and determined. Multiwalled carbon nanotubes were also PEGylated and PEGylation was found to be successful and effective. Particle sizes and zeta potentials of carbon nanotubes were not altered after PEGylation.