Formulation study of PLGA in situ films for topical delivery of salicylates.

A film-forming system (FFS) represents a convenient topical dosage form for drug delivery. In this study, a non-commercial poly(lactic-co-glycolic acid) (PLGA) was chosen to formulate an FFS containing salicylic acid (SA) and methyl salicylate (MS). This unique combination is advantageous from a therapeutic point of view, as it enabled modified salicylate release. It is beneficial from a technological perspective too, because it improved thermal, rheological, and adhesive properties of the in situ film. DSC revealed complete dissolution of SA and good miscibility of MS with the polymer. MS also ensures optimal viscoelastic and adhesive properties of the film, leading to prolonged and sustained drug release. The hydrolysis of MS to active SA was very slow at skin pH 5.5, but it apparently occurred at physiological pH 7.4. The film structure is homogeneous without cracks, unlike some commercial preparations. The dissolution study of salicylates revealed different courses in their release and the influence of MS concentration in the film. The formulated PLGA-based FFS containing 5 % SA and 10 % MS is promising for sustained and prolonged local delivery of salicylates, used mainly for keratolytic and anti-inflammatory actions and pain relief.

The use of scanning electron microscopy and fixation methods to evaluate the interaction of blood with the surfaces of medical devices.

Testing the hemocompatibility of medical devices after their interaction with blood entails the need to evaluate the activation of blood elements and the degree of their coagulation and adhesion to the device surface. One possible way to achieve this is to use scanning electron microscopy (SEM). The aim was to develop a novel SEM-based method to assess the thrombogenic potential of medical devices and their adhesiveness to blood cells. As a part of this task, also find a convenient procedure of efficient and non-destructive sample fixation for SEM while reducing the use of highly toxic substances and shortening the fixation time. A polymeric surgical mesh was exposed to blood so that blood elements adhered to its surface. Such prepared samples were then chemically fixed for a subsequent SEM measurement; a number of fixation procedures were tested to find the optimal one. The fixation results were evaluated from SEM images, and the degree of blood elements' adhesion was determined from the images using ImageJ software. The best fixation was achieved with the May-Grünwald solution, which is less toxic than chemicals traditionally used. Moreover, manipulation with highly toxic osmium tetroxide can be avoided in the proposed procedure. A convenient methodology for SEM image analysis has been developed too, enabling to quantitatively evaluate the interaction of blood with the surfaces of various medical devices. Our method replaces the subjective assessment of surface coverage with a better-defined procedure, thus offering more precise and reliable results.

The Alphabet of Nanostructured Polypyrrole.

This review is devoted to polypyrrole and its morphology, which governs the electroactivity of the material. The macroscopic properties of the material are strictly relevant to microscopic ordering observed at the local level. During the synthesis, various (nano)morphologies can be produced. The formation of the ordered structure is dictated by the ability of the local forces and effects to induce restraints that help shape the structure. This review covers the aspects of morphology and roughness and their impact on the final properties of the modified electrode activity in selected applications.

Analysis of SARS-CoV-2 interactions with the Vero cell lines by scanning electron microscopy.

In this study, scanning electron microscopy (SEM) was used to study the cell structure of SARS-CoV-2 infected cells. Our measurements revealed infection remodeling caused by infection, including the emergence of new specialized areas where viral morphogenesis occurs at the cell membrane. Intercellular extensions for viral cell surfing have also been observed. Our results expand knowledge of SARS-CoV-2 interactions with cells, its spread from cell to cell, and their size distribution. Our findings suggest that SEM is a useful microscopic method for intracellular ultrastructure analysis of cells exhibiting specific surface modifications that could also be applied to studying other important biological processes.

Effect of co-processed excipient type on properties of orodispersible tablets containing captopril, tramadol, and domperidone.

An important feature of orodispersible tablets (ODTs) is the convenient administration of the drugs, in some cases, faster onset of action, stability maintenance, and dose precision. This work focused on the preparation of ODTs containing mannitol-based co-processed excipients Prosolv® ODT G2, Ludiflash® and Parteck® ODT in combination with tramadol, captopril, and domperidone by direct compression. Prosolv® ODT G2 showed high energy of plastic deformation due to the content of microcrystalline cellulose. Parteck® ODT provided compact tablets due to the content of granulated mannitol. All drugs decreased tensile strength, increased friability, prolonged disintegration time, and decreased the porosity of tablets. Tablets containing Prosolv® ODT G2 with captopril, domperidone, and tramadol; and Parteck® ODT with domperidone met the requirements for ODTs production, i.e., friability ≤ 1% and disintegration time ≤ 180 s, fast wetting time, high water absorption ratio, and adequate tensile strength. The disintegration time was tested using both the pharmacopeial method and the BJKSN-13 apparatus. The results indicate the significant difference between these methods, with the disintegration time being longer when tested with the BJKSN-13 instrument.

Crystallization Kinetics and Structure Evolution during Annealing of Ni-Co-Mn-In Powders Obtained by Mechanical Alloying.

The crystallization kinetics and structure evolution during annealing of the Ni45.5Co4.5Mn36.6In13.4 (at. %) powders produced by mechanical alloying (MA) was investigated. After 70 h and 100 h of MA, the powder consisted of a mixture of amorphous and nanocrystalline body-centered cubic (bcc) phases. We observed the relaxation in the as-received powder. The relaxation temperature (Tre) increases logarithmically with the annealing time. Annealing above 440 °C results in (1) ordering of L21, (2) dissolution of the residual Ni and Mn, (3) tetragonal MnNi phase formation and (4) γ phases precipitation. The activation energies of the B2 → L21 and Mn (α-Mn) → MnNi (P4/mmm) transformations were calculated.

An extensive individual particle analysis of solid airborne particles collected in a moderately urbanized area.

Detailed individual particle characterization of PM10, in terms of particle size, morphology, and elemental composition, was done using scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. The samples were collected in four localities in the Czech Republic (Central Europe), three of which are medium-sized cities, and one is a natural locality in the mountains. More than 1600 particles obtained from each locality were evaluated. During the sampling period (1.9.-8.9.2019), the atmospheric conditions were similar in the localities, which enabled the identification of PM10 characteristics common to all the sampling sites. Some differences in the particles' morphology and composition, arising from site-specific conditions, were observed too. The most abundant elements in the PM10 were C, O, Si, Fe, Al, Ca, Na, K, Mg, and S, but some toxic elements (Cr, Cu, and Ni) were also detected. The main component of the PM10 is carbon, whose multimodal distribution indicates that the particles contain different carbonaceous chemical compounds. The distribution of carbon in the natural locality was different compared to the other sites, suggesting a specific character of the sources of carbonaceous compounds in this region. Last but not least, a relationship between Al, Si, and O concentrations was found, which implies the presence of aluminosilicates and silicon dioxide (possibly sand) of crustal origin in the particles.

Preparation and advanced characterization of highly drug-loaded, 3D printed orodispersible tablets containing fluconazole.

Due to the possibility of designing various spatial structures, three-dimensional printing can be implemented in the production of customized medicines. Nevertheless, the use of these methods for the production of dosage forms requires further optimization, understanding, and development of printouts' quality verification mechanisms. Therefore, the goal of our work was the preparation and advanced characterization of 3D printed orodispersible tablets (ODTs) containing fluconazole, printed by the fused deposition modeling (FDM) method. We prepared and analyzed 7 printable filaments containing from 10% to 70% fluconazole, used as model API. Obtaining a FDM-printable filament with such a high API content makes our work unique. In addition, we confirmed the 12-month stability of the formulation, which, to our knowledge, is the first study of this type. Next, we printed 10 series of porous tablets containing 50 mg of API from both fresh and stored filaments containing 20 %, 40 %, or 70 % fluconazole. We confirmed the high quality and precision of the printouts using scanning electron microscopy. The detailed analysis of the tablets' disintegration process included the Pharmacopeial test, but also the surface dissolution imaging analysis (SDI) and the test simulating oral conditions performed in own-constructed apparatus. For each composition, we obtained tablets disintegrating in less than 3 min, i.e., meeting the criteria for ODTs required by the European Pharmacopeia. The filaments' storage at ambient conditions did not affect the quality of the tablets. All printed tablets released over 95% of the fluconazole within 30 min. Moreover, the printouts were stable for two weeks.

Allogeneic Bone Impregnated with Biodegradable Depot Delivery Systems for the Local Treatment of Joint Replacement Infections: An In Vitro Study.

Although progress is evident in the effective treatment of joint replacement-related infections, it still remains a serious issue in orthopedics. As an example, the local application of antibiotics-impregnated bone grafts supplies the high drug levels without systemic side effects. However, antibiotics in the powder or solution form could be a risk for local toxicity and do not allow sustained drug release. The present study evaluated the use of an antibiotic gel, a water-in-oil emulsion, and a PLGA microparticulate solid dispersion as depot delivery systems impregnating bone grafts for the treatment of joint replacement-related infections. The results of rheological and bioadhesive tests revealed the suitability of these formulations for the impregnation of bone grafts. Moreover, no negative effect on proliferation and viability of bone marrow mesenchymal stem cells was detected. An ex vivo dissolution test of vancomycin hydrochloride and gentamicin sulphate from the impregnated bone grafts showed a reduced burst and prolonged drug release. The PLGA-based formulation proved to be particularly promising, as one-day burst release drugs was only 15% followed with sustained antibiotics release with zero-order kinetics. The results of this study will be the basis for the development of a new product in the Tissue Section of the University Hospital for the treatment of bone defects and infections of joint replacements.

A Complex In Vitro Degradation Study on Polydioxanone Biliary Stents during a Clinically Relevant Period with the Focus on Raman Spectroscopy Validation.

Biodegradable biliary stents are promising treatments for biliary benign stenoses. One of the materials considered for their production is polydioxanone (PPDX), which could exhibit a suitable degradation time for use in biodegradable stents. Proper material degradation characteristics, such as sufficient stiffness and disintegration resistance maintained for a clinically relevant period, are necessary to ensure stent safety and efficacy. The hydrolytic degradation of commercially available polydioxanone biliary stents (ELLA-CS, Hradec Králové, Czech Republic) in phosphate-buffered saline (PBS) was studied. During 9 weeks of degradation, structural, physical, and surface changes were monitored using Raman spectroscopy, differential scanning calorimetry, scanning electron microscopy, and tensile and torsion tests. It was found that the changes in mechanical properties are related to the increase in the ratio of amorphous to crystalline phase, the so-called amorphicity. Monitoring the amorphicity using Raman spectroscopy has proven to be an appropriate method to assess polydioxanone biliary stent degradation. At the 1732 cm-1 Raman peak, the normalized shoulder area is less than 9 cm-1 which indicates stent disintegration. The stent disintegration started after 9 weeks of degradation in PBS, which agrees with previous in vitro studies on polydioxanone materials as well as with in vivo studies on polydioxanone biliary stents.

Fused Deposition Modeling as a Possible Approach for the Preparation of Orodispersible Tablets.

Additive manufacturing technologies are considered as a potential way to support individualized pharmacotherapy due to the possibility of the production of small batches of customized tablets characterized by complex structures. We designed five different shapes and analyzed the effect of the surface/mass ratio, the influence of excipients, and storage conditions on the disintegration time of tablets printed using the fused deposition modeling method. As model pharmaceutical active ingredients (APIs), we used paracetamol and domperidone, characterized by different thermal properties, classified into the various Biopharmaceutical Classification System groups. We found that the high surface/mass ratio of the designed tablet shapes together with the addition of mannitol and controlled humidity storage conditions turned out to be crucial for fast tablet's disintegration. As a result, mean disintegration time was reduced from 5 min 46 s to 2 min 22 s, and from 11 min 43 s to 2 min 25 s for paracetamol- and domperidone-loaded tablets, respectively, fulfilling the European Pharmacopeia requirement for orodispersible tablets (ODTs). The tablet's immediate release characteristics were confirmed during the dissolution study: over 80% of APIs were released from printlets within 15 min. Thus, this study proved the possibility of using fused deposition modeling for the preparation of ODTs.

Study of rheological and tableting properties of lubricated mixtures of co-processed dry binders for orally disintegrating tablets.

Co-processed dry binders for ODTs are important multifunctional excipients for tablet manufacturing by direct compression. Testing their binary mixtures with lubricants is an important aspect of their use in combination with drugs. The aim of this study was to evaluate the rheological and compression properties of lubricated mixtures of co-processed dry binders Parteck® ODT, Prosolv® ODT G2 and Ludiflash®, and subsequently also the compactability and disintegration time of the tablets made thereof. The lubricants employed were magnesium stearate and sodium stearyl fumarate in the concentrations of 0.5% and 1%. The best flowability was shown by Prosolv® ODT G2 combined with magnesium stearate in the concentration of 0.5%. Lubricated mixtures with Prosolv® ODT G2 showed a lower angle of internal friction as well as lower pre-compression energy values. The values of plastic deformation energy were the highest in the case of Prosolv® ODT G2, which was also reflected in the highest tablet strength. On the contrary, the ejection force values were the lowest for this co-processed dry binder. Magnesium stearate reduced the ejection force more effectively than sodium stearyl fumarate. Prosolv® ODT G2 tablets exhibited the highest tensile strength and shortest disintegration time.

Raman Spectroscopy as a Novel Method for the Characterization of Polydioxanone Medical Stents Biodegradation.

Polydioxanone (PPDX), as an FDA approved polymer in tissue engineering, is an important component of some promising medical devices, e.g., biodegradable stents. The hydrolytic degradation of polydioxanone stents plays a key role in the safety and efficacy of treatment. A new fast and convenient method to quantitatively evaluate the hydrolytic degradation of PPDX stent material was developed. PPDX esophageal stents were degraded in phosphate-buffered saline for 24 weeks. For the first time, the changes in Raman spectra during PPDX biodegradation have been investigated here. The level of PPDX hydrolytic degradation was determined from the Raman spectra by calculating the area under the 1732 cm-1 peak shoulder. Raman spectroscopy, unlike Fourier transform infrared (FT-IR) spectroscopy, is also sensitive enough to monitor the decrease in the dye content in the stents during the degradation. Observation by a scanning electron microscope showed gradually growing cracks, eventually leading to the stent disintegration. The material crystallinity was increasing during the first 16 weeks, suggesting preferential degradation of the amorphous phase. Our results show a new easy and reliable way to evaluate the progression of PPDX hydrolytic degradation. The proposed approach can be useful for further studies on the behavior of PPDX materials, and for clinical practice.

PLGA based film forming systems for superficial fungal infections treatment.

As proven in clinical trials, superficial fungal infections can be effectively treated by single topical application of terbinafine hydrochloride (Ter-HCl) in a film forming system (FFS). Poly(lactic-co-glycolic acid) (PLGA) derivatives, originally synthesized with intention to get carriers with optimized properties for drug delivery, and multifunctional plasticizers - ethyl pyruvate, methyl salicylate, or triacetin - were used for formulation of Ter-HCl loaded FFSs. After spraying, a biodegradable, transparent, adhesive, and occlusive thin layer is formed on the skin, representing drug depot. In situ formed films were characterized by thermal, structural, viscoelastic, and antifungal properties as well as drug release and skin penetration. DSC and SEM showed fully amorphous films with Ter-HCl dissolved in PLGA in high concentration (up to 15%). FFSs are viscoelastic fluids with viscosity which can be easily adjusted by the type of plasticizer used and its concentration. The formulations showed excellent bioadhesion properties, thus ensuring persistence on the skin. In situ film based on branched PLGA/A plasticized with 10% of ethyl pyruvate allowed prolonged release of Ter-HCl by linear kinetics for the first 6 days with a total time of almost 14 days. During ex vivo human skin penetration experiment, Ter-HCl was found to be located only in its target layer, the epidermis. According to our results, plasticized branched PLGA derivatives loaded by Ter-HCl are suitable for the development of FFSs for superficial fungal infections treatment.

Terbinafine-loaded branched PLGA-based cationic nanoparticles with modifiable properties.

Although the systemic administration of terbinafine is quite well tolerated, topical treatment of the local infections is often preferred. New formulation strategies in topical antifungal therapy represent the polymeric nanoparticles (NPs). We successfully employed the originally synthesized PLGA derivatives of branched architectures of various molar masses, branching ratio, and high number of terminal hydroxyl or carboxyl groups for compounding of terbinafine loaded nanoparticles by nanoprecipitation method. Employing the polymers with tailored properties allowed us to formulate the NPs with desired particle size, loading capacity for drug, mucoadhesive properties, and drug release profile. The hydrophobicity and the polyester concentration revealed the main impact on the NPs size ranging from 100 to 600 nm. The stability of the nanosuspension is demonstrated by zeta potential >25 mV, and polydispersity index values <0.2. We used terbinafine in its less dissolved form of the base to increase the drug loading and delay the release. Cationic surfactant as stabilizer give the NPs high positive surface charge enhancing the adhesion to the mucosal surfaces. All formulations provided prolonged sustained release of terbinafine for several days. Antimicrobial potential has been proven by agar-well diffusion method.