Micro-organism resistance is an important challenge in modern medicine due to the global uncontrolled use of antibiotics. Natural and synthetic antimicrobial peptides (AMPs) symbolize a new family of antibiotics, which have stimulated research and clinical interest as new therapeutic options for infections. They represent one of the most promising antimicrobial substances, due to their broad spectrum of biological activity, against bacteria, fungi, protozoa, viruses, yeast and even tumour cells. Besides, being antimicrobial, AMPs have been shown to bind and neutralize bacterial endotoxins, as well as possess immunomodulatory, anti-inflammatory, wound-healing, angiogenic and antitumour properties. In contrast to conventional antibiotics, which have very defined and specific molecular targets, host cationic peptides show varying, complex and very rapid mechanisms of actions that make it difficult to form an effective antimicrobial defence. Importantly, AMPs display their antimicrobial activity at micromolar concentrations or less. To do this, many peptide-based drugs are commercially available for the treatment of numerous diseases, such as hepatitis C, myeloma, skin infections and diabetes. Herein, we present an overview of the general mechanism of AMPs action, along with recent developments regarding carriers of AMPs and their potential applications in medical fields.

Biodegradable or bioresorbable polymers are commonly used in various pharmaceutical fields (e.g., as drug delivery systems, therapeutic systems or macromolecular drug conjugates). Polyesters are an important class of polymers widely utilized in pharmacy due to their biodegradability and biocompatibility features. In recent years, there has been increased interest in enzyme-catalyzed ring-opening polymerization (e-ROP) of cyclic esters as an alternative method of preparation of biodegradable or bioresorbable polymers. Ionic liquids (ILs) have been presented as green solvents in enzymatic ring-opening polymerization. The activity, stability, selectivity of enzymes in ILs and the ability to catalyze polyester synthesis under these conditions are discussed. Overall, the review demonstrates that e-ROP of lactones or lactides could be an effective method for the synthesis of useful biomedical polymers.

Hydroxyapatite (HA) powders enriched with silver or gallium ions or both were synthesized by two different routes: standard precipitation and the solid-state method. The powders were characterized by using several methods: inductively coupled plasma optical emission spectrometry (ICP-OES), powder X-ray diffractometry (PXRD), transmission electron microscopy (TEM), infrared spectroscopy (FT-IR) and solid-state nuclear magnetic resonance spectroscopy (ssNMR). The effects of enrichment of the HAs in Ag+ or Ga3+ or both on in vitro cytotoxicity and microbiological activity were discussed. PXRD experiments showed that the samples obtained by the wet method consisted of single-phase nanocrystalline HA, while the samples prepared via the solid-state method are microcrystalline with a small amount of calcium oxide. The introduction of higher amounts of silver ions was found to be more effective than enriching HA with small amounts of Ag+. Gallium and silver ions were found not to affect the lattice parameters. Ga3+ affected the crystallinity of the samples as well as the content of structural hydroxyl groups. Among samples synthesized by the wet method, only one (5Ag-HAw) was cytotoxic, whereas all Ga-containing samples obtained by the dry method showed cytotoxicity. In the preliminary antimicrobial test all the materials containing “foreign” ions showed high antibacterial activity.

In this work, we used the co-precipitation method to synthesize hydroxyapatite (Mn-SeO3-HA) containing both selenium IV (approximately 3.60 wt.%) and manganese II (approximately 0.29 wt.%). Pure hydroxyapatite (HA), hydroxyapatite-containing manganese (II) ions (Mn-HA), and hydroxyapatite-containing selenite ions alone (SeO3-HA), prepared with the same method, were used as reference materials. The structures and physicochemical properties of all the obtained samples were investigated. PXRD studies showed that the obtained materials were homogeneous and consisted of apatite phase. Introducing selenites into the hydroxyapatite crystals considerably affects the size and degree of ordering. Experiments with transmission electron microscopy (TEM) showed that Mn-SeO3-HA crystals are very small, needle-like, and tend to form agglomerates. Fourier transform infrared spectroscopy (FT-IR) and solid-state nuclear magnetic resonance (ssNMR) were used to analyze the structure of the obtained material. Preliminary microbiological tests showed that the material demonstrated antibacterial activity against Staphylococcus aureus, yet such properties were not confirmed regarding Escherichia coli.PACS codes: 61, 76, 81Electronic supplementary materialThe online version of this article (doi:10.1186/s11671-015-0989-x) contains supplementary material, which is available to authorized users.

Surface active compounds may act as effective additives modifying water lubricity. Their action mechanism consists in the formation of a lubricating film enriched with an active compound. The reasons for the choice of polyvinylpyrrolidones as additives were their physiological inertness and a lack of harmful environmental effects. The tests were carried out on the solutions of two polyvinylpyrrolidones with degrees of polymerization of 450 (PVP 450) and 14400 (PVP 14400). A significant effect of the polymer chain length on physicochemical (viscosity, surface tension, wettability of steel) and tribological properties (resistance to motion, wear, scuffing) has been found. PVP 14400 showed a considerably greater ability to thicken solutions. Over 10 times higher coefficients of viscosity relative to an analogous PVP 450 solution were observed already at a concentration of 5%. A slightly higher ability of PVP 14400 to reduce surface tension was observed. In the case of wettability of steel, a more effective decrease in the wetting angle was observed for PVP 450. However, the differences obtained were not large and usually did not exceed 20%. The measurements of resistance to motion and wear at three constant loads (2000, 3000, 4000 N) as well as tests on antiseizure abilities under a constant velocity increment of load (409 N/s) were carried out using a four-ball tester (T-02 tester). All friction pairs were made of bearing steel. Introducing additives to water significantly affects a decrease in resistance to motion and wear as well as an increase in the ability of a tribological system to prevent seizure. The system did not undergo seizure even at a load of 4 kN. A 2-fold decrease in the coefficient of friction (μ) and an over 30% decrease in the value of wear scar diameters (d) relative to water were observed for PVP 450 and PVP 14400 solutions at 2.0 kN. The use of water as a lubricant led to seizure of the tribological system already at above 2 kN. Addition of the polymers to water also results in a significant improvement in its antiseizure properties. The values of scuffing load (P t) and limiting pressure of seizure (p oz) for individual solutions were even 5 and 15 times higher, respectively, than the values for water. Seizure load (P oz) was also relatively high, and its level was almost two times higher than that for water. The results obtained indicate that polyvinylpyrrolidone used as an additive considerably improves the tribological characteristics of water as a lubricant base.