Diffusion-Controlled Drug Release From the Mesoporous Magnesium Carbonate Upsalite(®).

In vitro drug release from well-defined particle-size fractions of the mesoporous magnesium carbonate material Upsalite(®) was investigated in detail using ibuprofen, a biopharmaceutics classification system class II drug, as the model compound. The weight of loaded drug corresponded to 30% of the weight of the carrier and the pores were filled to approximately 80%. The incorporated ibuprofen was found to be in an amorphous state and was physisorbed, rather than chemisorbed, to the surfaces of the pore walls.

Stabilisation of amorphous ibuprofen in Upsalite, a mesoporous magnesium carbonate, as an approach to increasing the aqueous solubility of poorly soluble drugs.

One attractive approach to increase the aqueous solubility and thus the bioavailability of poorly soluble drugs is to formulate them in their amorphous state since amorphous compounds generally exhibit higher apparent solubilities than their crystalline counterparts. In the current work, mesoporous magnesium carbonate was used to stabilise the amorphous state of the model substance ibuprofen. Crystallisation of the drug was completely supressed in the formulation, resulting in both a higher apparent solubility and a three times faster dissolution rate of the drug where the drug release was shown to be diffusion controlled.

Aspirin degradation in surface-charged TEMPO-oxidized mesoporous crystalline nanocellulose.

TEMPO-mediated surface oxidation of mesoporous highly crystalline Cladophora cellulose was used to introduce negative surface charges onto cellulose nanofibrils without significantly altering other structural characteristics. This enabled the investigation of the influence of mesoporous nanocellulose surface charges on aspirin chemical stability to be conducted. The negative surface charges (carboxylate content 0.

A template-free, ultra-adsorbing, high surface area carbonate nanostructure.

We report the template-free, low-temperature synthesis of a stable, amorphous, and anhydrous magnesium carbonate nanostructure with pore sizes below 6 nm and a specific surface area of ∼ 800 m(2) g(-1), substantially surpassing the surface area of all previously described alkali earth metal carbonates. The moisture sorption of the novel nanostructure is featured by a unique set of properties including an adsorption capacity ∼50% larger than that of the hygroscopic zeolite-Y at low relative humidities and with the ability to retain more than 75% of the adsorbed water when the humidity is decreased from 95% to 5% at room temperature. These properties can be regenerated by heat treatment at temperatures below 100°C.

Mesoporous calcium carbonate as a phase stabilizer of amorphous celecoxib--an approach to increase the bioavailability of poorly soluble pharmaceutical substances.

The bioavailability of crystalline pharmaceutical substances is often limited by their poor aqueous solubility but it can be improved by formulating the active substance in the amorphous state that is featured with a higher apparent solubility. Although the possibility of stabilizing amorphous drugs inside nano-sized pores of carbon nanotubes and ordered mesoporous silica has been shown, no conventional pharmaceutical excipients have so far been shown to possess this property. This study demonstrates the potential of using CaCO3 , a widely used excipient in oral drug formulations, to stabilize the amorphous state of active pharmaceutical ingredients, in particular celecoxib.

Laser induced surface structuring and ion conversion in the surface oxide of titanium: possible implications for the wetability of laser treated implants.

In the present study, commercially pure titanium was irradiated with UV-light with varying wavelengths using a Q-switched Nd:YAG-laser. This was performed in order to investigate if a laser treatment can be employed to rapidly introduce hydrophilic properties to titanium surfaces, which is believed to facilitate protein adsorption and cell attachment. It was demonstrated that irradiation with 355 nm light (10 Hz, 90 mJ/shot) for 1 min or more caused an ion conversion of Ti(4+) to Ti(3+) sites in the surface oxide which lead to an increase in hydrophilicity of the surface.

Photocatalytic and antimicrobial properties of surgical implant coatings of titanium dioxide deposited though cathodic arc evaporation.

Unlabelled: Nanostructured crystalline titanium dioxide coatings deposited by cathodic arc evaporated on titanium grade five medical implant substrates were demonstrated to exhibit UV-induced photocatalytic activity that can be utilized to provide bactericidal effects against Staphylococcus epidermidis. The photocatalytic activity of the coatings was confirmed via degradation of Rhodamine B under UV illumination. A 90 % reduction of viable bacteria was achieved in a clinically suitable time of only 2 min with a UV dose of 2.

Synthetic geopolymers for controlled delivery of oxycodone: adjustable and nanostructured porosity enables tunable and sustained drug release.

In this article we for the first time present a fully synthetic mesoporous geopolymer drug carrier for controlled release of opioids. Nanoparticulate precursor powders with different Al/Si-ratios were synthesized by a sol-gel route and used in the preparation of different geopolymers, which could be structurally tailored by adjusting the Al/Si-ratio and the curing temperatures. In particular, it was shown that the pore sizes of the geopolymers decreased with increasing Al/Si ratio and that completely mesoporous geopolymers could be produced from precursor particles with the Al/Si ratio 2:1.

Co-loading of bisphosphonates and antibiotics to a biomimetic hydroxyapatite coating.

We have incorporated bisphosphonates and antibiotics simultaneously into a biomimetic hydroxyapatite implant coating aiming to use the interaction between drug-molecules and hydroxyapatite to enable local release of the two different substances to obtain a dual biological effect. A sustained release over for 43 h of antibiotics (cephalothin) was achieved without negative interference from the presence of the bisphosphonate (clodronate) which, in turn, successfully bonded to the coating surface. To our knowledge, this is the first study that indicates the possibility to simultaneously incorporate both antibiotics and bisphosphonates to an implant coating, a strategy that is believed to improve implant stability and reduce implant-related infections.

Mechanically strong geopolymers offer new possibilities in treatment of chronic pain.

We propose that a clay derived class of materials, known as geopolymers, may solve the problem of finding materials for controlled release with the right combination of properties necessary for a safe and sustained oral delivery of highly potent opioids. We show that the opioid Fentanyl, and its structurally similar sedative Zolpidem, can be embedded into metakaolin based geopolymer pellets to provide prolonged release dosage forms with mechanical strengths of the same order of magnitude as that of human teeth. The results presented in the current work may open up new opportunities for future development of drug delivery for high potency drugs employing high-strength and variable-pore-structure geopolymers and materials alike.

A novel method for local administration of strontium from implant surfaces.

This study proves that a film of Strontianite (SrCO(3)) successfully can be formed on a bioactive surface of sodium titanate when exposed to a strontium acetate solution. This Strontianite film is believed to enable local release of strontium ions from implant surfaces and thus stimulate bone formation in vivo. Depending on the method, different types of films were achieved with different release rates of strontium ions, and the results points at the possibility to tailor the rate and amount of strontium that is to be released from the surface.

In vitro characterization of bioactive titanium dioxide/hydroxyapatite surfaces functionalized with BMP-2.

Poor implant fixation and bone resorption are two of the major challenges in modern orthopedics and are caused by poor bone/implant integration. In this work, bioactive crystalline titanium dioxide (TiO(2))/hydroxyapatite (HA) surfaces, functionalized with bone morphogenetic protein 2 (BMP-2), were evaluated as potential implant coatings for improved osseointegration. The outer layer consisted of HA, which is known to be osteoconductive, and may promote improved initial bone attachment when functionalized with active molecules such as BMP-2 in a soaking process.

A ceramic drug delivery vehicle for oral administration of highly potent opioids.

Pellets composed of the ceramic material Halloysite and microcrystalline cellulose were synthesized with the aim of producing a drug delivery vehicle for sustained release of the opioid Fentanyl with low risk for dose dumping at oral intake of the highly potent drug. Drug release profiles of intact and crushed pellets, to simulate swallowing without or with chewing, in pH 6.8, pH 1, and in 48% ethanol were recorded in order to replicate the conditions in the small intestines, in the stomach, as well as cointake of the drug with alcohol.

Multifunctional implant coatings providing possibilities for fast antibiotics loading with subsequent slow release.

The possibility to fast-load biomimetic hydroxyapatite coatings on surgical implant with the antibiotics Amoxicillin, Gentamicin sulfate, Tobramycin and Cephalothin has been investigated in order to develop a multifunctional implant device offering sustained local anti-bacterial treatment and giving the surgeon the possibility to choose which antibiotics to incorporate in the implant at the site of surgery. Physical vapor deposition was used to coat titanium surfaces with an adhesion enhancing gradient layer of titanium oxide having an amorphous oxygen poor composition at the interface and a crystalline bioactive anatase TiO(2) composition at the surface. Hydroxyapatite (HA) was biomimetically grown on the bioactive TiO(2) to serve as a combined bone in-growth promoter and drug delivery vehicle.

Assessing surface area evolution during biomimetic growth of hydroxyapatite coatings.

The surface area of biomimetically deposited hydroxyapatite (HA) coatings on metallic implants is important for the biological performance of the implant. Thus, a nondestructive method of assessing this quantity directly on the solid substrate would be highly valuable. The objective of this study was to develop such a method and for the first time assess the evolution of surface area of HA during biomimetic growth.

Formation and adhesion of biomimetic hydroxyapatite deposited on titanium substrates.

This study has been carried out to investigate the bioactivity of rutile and to deposit hydroxyapatite (HA) on heat-treated titanium through a biomimetic method. Biomimetic deposition of HA has gained large interest because of its low deposition temperature and good step coverage; however, it demands a substrate with bioactive properties. Commercially pure titanium is not bioactive but it can acquire bioactive properties through various surface treatments.