Nanostructured Metal Polyacrylates as Both Local Hemostatics and Antimicrobials

Abstract

A methodological approach to directed synthesis of biopharmaceutical composites allows solving an urgent problem: the development of fundamentally new high-molecular materials intended for the interaction of synthetic substances with the biological environment, e.g., with blood. Polymer composites containing ionogenic groups and nanoparticles are capable of complementary conformational transformations and cooperative binding. Functional polymer materials with a wide range of biological activity have been designed on the basis of essential elements and nanoparticles of noble metals. Potential hemostatics with unique properties are proposed. They can be employed as universal agents in a wide variety of surgical operations, as well as for healing the wounds and injuries in case of emergency. At the same time, they stop bleeding even in patients with disorders of the blood coagulation system. The polymer composites can find application as unprecedented, highly effective drugs with a wide range of pharmacological activity. Innovative potential drugs based on polymer composites acting as hemostatics, asepsis, antiseptics without antibiotics, reparants, analgesics, and cytostatics can effectively solve the problems of modern medicine including disaster medicine.

1. Introduction

The design of polymer-based nanocomposites with tailor-made represents an urgent challenge for research community. The development of methodological approach to establishing the relationship between the molecular architecture and properties of compounds is a fundamental task in the synthesis of multifunctional synthetic polymers [1, 2, 3]. The targeted synthesis of polymers containing nanoparticles and ions of bioelements is one of the most important directions in the field of molecular biology. The creation of new drugs is based on the principles of biological processes and the study of intermolecular interactions of complementary macromolecules and the products of these reactions. Over the last decade, interest in polymer medicinal substances has increased due to the discovery of their specific pharmacological properties, which are determined by the macromolecular nature of the substance, its structure, and conformational and configuration features [4, 5]. The preparation of polymer composites is based on the understanding of the above processes and the use of the most important ideas of chemistry of supramolecular compounds, which are characterized by the spatial arrangement of their components, “suprastructure,” and types of intermolecular interactions. The interaction of such structures and the products of their associations play an important role in living organisms. The study of such interactions enables simulation of biological structures, functions, and processes. The participation of synthetic macromolecules in these processes stimulates the development of chemical approaches. The creation of medicine-oriented nanocomposites, in particular hemostatic agents, through the study of the interaction between materials of non-physiological origin with the surrounding biological fluids, tissues, and, first of all, with blood is an innovative solution to the problem. The application of synthetic polymer nanocomposites is a very promising area. Research in this field aims to form innovative potential through new competitive drugs based on polymer composites containing nanoparticles and bioelements.

One of the priority tasks is the search for effective hemostatic agents that simultaneously possess a wide range of pharmacological activity. The theoretical and experimental investigations into the nature of the relationship between the structure, physical and chemical properties, and pharmacological activity of chemical compounds have led to the creation of potential drugs with a wide range of biopharmaceutical characteristics. These new compounds are based on polymers containing nanoparticles and essential metal ions, which determine their practically significant properties and the possibility of their application as new highly effective drugs.

The development of hemostatics of new generation is challenging for bleeding control in practical and clinical medicine, surgical interventions, critical and exigent conditions during combats and disasters as well as for protection of people from the consequences of damaging factors of emergency situations. Against the background of blood component deficiency and high rates of mortality both from bleeding and from post-hemorrhagic complications, the implementation of pharmacological ways to reduce blood loss is crucial. Existing hemostatic drugs (systemic and local) affect individual components of the blood coagulation system and are not effective. Moreover, their administration is technically quite complex procedure.

2. Modern local hemostatics

Currently, many hemostatic agents are manufactured from blood components by the pharmaceutical companies. Unfortunately, these hemostatics are not free from significant drawbacks. First of all, their manufacture requires a large amount of scarce donor blood, which is a potentially biologically hazardous substance, since human blood plasma should be considered as possibly infected and capable of long storing and transmitting the viruses of immunodeficiency HIV1 and HIV2, hepatitis B, etc. In addition, these hemostatic agents exhibit anaphylactic properties and have limited storage time. Finally, the production of hemostatic agents from blood components needs special expensive equipment and sophisticated technologies. For example, the hemostatic thrombin [6], a natural component of the blood coagulation system, which is used intraoperatively in the form of bovine thrombin or recombinant human thrombin, can cause secondary infection and allergic reactions. It cannot be administrated in case of hypersensitivity and bleeding from large vessels in view of possible extensive thrombosis and even fatal outcome.

Fibrinogen, a human blood product, is a factor of the coagulation system, which is not used in its pure form as a local hemostatic agent, since it can cause blood microclotting. Together with thrombin, it belongs to local hemostatic agents and fibrin adhesives [7]. The latter usually consist of thrombin, fibrinogen, and coagulation factor XIII, released from donor blood. The hemostatic effect of adhesives (biokol, beriplast, bohil, hemasil APR, quixil, tissell, and tissucol) is based on platelet aggregation on a branched network of collagen fibers of the plate. They are widely employed for sealing the scratches and arrest of bleeding from parenchymal organs [8, 9, 10]. Fibrin adhesive tissucol is a highly effective local hemostatic agent used in modern surgery. During its administration, the main stages of the physiological process of blood coagulation are repeated. This enables to stop diffuse bleeding, glue and fix tissue, and accelerate wound healing [11, 12]. However, but from technical perspective it is quite difficult to use two-component fibrin glue tissucol, since one should warm and intraoperatively mix the components. Also, a special device for applying adhesive to the wound surface is required [13].

Beriplast is more convenient in terms of preparation of components and their application [14, 15]. A hemostatic sponge prepared from human blood plasma with the addition of calcium chloride and ε-aminocaproic acid is additionally saturated with antibiotics to arrest bleeding from infected wounds [16]. Collagen holds a special place among natural polymers with hemostatic properties. It is one of the main structural proteins of the body, which induces spontaneous platelet aggregation. Collagen was employed to design protein hemostatic agents that stimulate the coagulation of phospholipid-dependent blood and increase the adhesiveness of blood cells due to the activation of platelet-derived blood coagulation factors. The efficiency of collagen-based products is also determined by the effect of medicines contained in them [17].

A hemostatic agent, thrombocol, is a resorbable hemostatic coating of immediate action. It represents a biocomposition of collagen with highly concentrated blood coagulation factors and antibacterial agents [15] The TachoComb drug is a collagen plate impregnated with lyophilized components (fibrinogen, thrombin, and protein). It is intended for arrest of parenchymal bleeding in surgery (liver, pancreas, and spleen), neurosurgery, and trauma [18]. A general hemostatic agent, gelatin is a product of partial hydrolysis of collagen contained in the cartilage and bones of animals. Gelatin improves blood coagulation, accelerates the development of blood clots at the site of application, adheres to the damaged bleeding surface, and thereby ensures hemostasis. Application of gelatin may be accompanied by skin allergic reactions and the formation of small foci of necrosis. Gelatin, used as a support for thrombin, is used as a hemostatic agent [19].

The known hemostatic agent “Zhelplastan” consists of animal plasma containing various blood coagulation factors, edible gelatin, and kanamycin. It improves hemostasis on the background of the normal state of the blood coagulation system, exhibits antibacterial effect, and possesses adhesive properties [20]. Although the above hemostatic agents have their own advantages, e.g., good tolerance, they are sensitive to viruses and harmful organisms that can cause infectious diseases or severe allergic reactions. The oxidized regenerated cellulose is intensively employed as a hemostatic agent. It is more effective than collagen and gelatin. The mechanism of its action is diverse: It adsorbs and fixes coagulation factors and platelets and also causes vasoconstriction in the area of its application due to the low pH. It ensures hemostasis not only in vase of capillary and parenchymal bleeding, but also for venous and arterial bleeding. Highly oxidized cellulose can be used as a non-toxic hemostatic, antimicrobial, and wound-healing agent [21].

Hemostatics prepared from cellulose and its derivatives are used in the form of sponges (sterispan, spongostan, gelfoam, spongiopost, spongel, and surgicel) [22, 23]. In modern medicine, many hemostatic agents are created from natural biological materials, such as the polysaccharide chitin and its deacetylated derivative, chitosan [24, 25, 26]. These agents are more effective than oxidized cellulose and, therefore, collagen and gelatin. They are intended to provide first aid in arresting the major massive bleeding in extreme and emergency cases, as well as in stopping the diffuse and profuse bleeding during surgical operations [27]. The mechanism of their action involves the ionic interaction between the positive charge of the polymer and the negative charge of the erythrocyte cell membrane, which causes an active adhesive effect and stimulates plasma hemostasis. Also, mixtures of chitosan with biologically inert artificial multi-purpose polymers; for example, polyethylene oxide [28] or polyvinyl alcohol [29] are used. The expensive chitosan is used in a relatively narrow range of molecular weight and with a low degree of deacetylation. This together with complex composition of chitosan limits its application in pharmacology and biomedicine [30]. Hemostatic agents based on alginic acid are being developed [31, 32].

Combined hemostatics, which act at various stages of the hemostatic cascade, are also proposed. Among them is Algigemostat containing calcium alginate ensuring rapid thrombosis formation, oak bark causing partial coagulation of plasma proteins, ε-aminocaproic acid inhibiting fibrinolysis, and chlorhexidine preventing wound infection [33]. To date, various compositions based on synthetic polymers have been developed [34]. The Hemostop drug, which is efficient against external bleeding, represents a mixture of synthetic zeolites. Among its significant drawbacks are difficulties in application and possible burns [19]. Hemostatic agents are also designed on the basis of cyanoacrylate adhesives [35]. Synthetic polyethylene hydrogel can be used as an effective local hemostatic during laparoscopic nephrectomy [36]. Inorganic metal compounds (Cu, Ag, Zn, Al, Pb, Bi, and Fe) are employed as local hemostatic agents [37, 38, 39]. However, these drugs are toxic, have side effects, and are not effective enough.

3. Nanostructured metal polyacrylates as a new generation of local hemostatic agents

The global economic and methodological task of synthetic chemistry is to increase predictability of synthesis and to eliminate hundreds of “blind” syntheses. The predictability of designing new polymers with a wide range of useful properties is achieved using an analytical approach and accumulated theoretical and empirical ideas about the nature of the relationship between the structure, physical, and chemical properties and pharmacological activity of compounds. Modern technologies for creation of new drugs are based on the principles of biological processes. The simulation of a biologically active compound relies upon the structural parameters of the ligand and target. In order to design medicine-oriented polymers, in particular, hemostatic agents, the interactions of non-physiological materials with the surrounding biological fluids, tissues, and, first of all, with blood have been studied. The choice of target is predetermined by the fine structural mechanism of action of albumin, which is a physiologically active major protein in blood plasma. Its unique ability to bind a large number of ligands, present in the molecule, via several binding centers determines the role of albumin as a biotarget. The most interesting and promising compounds are polymer composites derived from nanoparticles and essential elements, which define their practically significant properties.

Metal-polymer composite materials, which contain both organic and inorganic components, are synthesized according to the general scheme on example of silver-containing composite (Figure 1) and characterized by a wide range of biological activity.

Figure 1.

General scheme for the synthesis of nanostructured metal-polymer complexes using silver-containing ones as an example.

Moreover, the properties of metal-polymer composites are not simple combination of the properties of their components, but they are significantly modified and improved due to the nature of the metal and the size effect of nanoparticles [40]. Typically, the bonding between a metal ion and a polymer ligand occurs through donor–acceptor interaction to form a coordination bond (chelate complexes) [41, 42, 43] or via substitution of the ligand proton with a metal ion to form an ionic bond [44, 45, 46]. The reduction of metal ions [47, 48] in solutions of suitable polymers affords sols, in which the high activity of metal nanoparticles in the absence of stabilizers leads to aggregation into larger particles. The resistance to aggregation and oxidation of metal nanoparticles in these sols depends on macromolecular shielding. Steric stabilization of nanoparticles with polymers or shielding with a protective colloid is due to the need to increase the stability of nanocomposites and control reversible transitions in such systems.

Metal-polymer complexes (MPC) based on macro-, micro-, ultra-bioelements, and nanoparticles of noble metals: Li, K, Rb, Cs, Ag, Au, and Zn correspond to the general formula (-CH2-СН-СOOH)n(-CH2-СН-СOOM)m, where n = 1200–3500; m = 1650–6650. Their molecular weight ranges from 1000 to 3000 kD. In the IR spectrum, the absorption bands of the ionized carboxyl group ⁻СОО (valence vibration: asymmetric at 1550–1540 cm⁻¹ and symmetric at 1400–1410 cm⁻¹), nonionized carboxyl group СООН at 1694–1649 cm⁻¹ as well as associated OH in the area 3420–2554 cm⁻¹ are visible (Figure 2) [49].

Figure 2.

Typical IR spectrum of MPCs.

Probably, MPCs are represented by metal nanoparticles (Figure 3) incorporated in radicals-enriched macromolecular polyacrylate framework [50].

Figure 3.

TEM photos and histograms of particle size distribution for: Ag-MPCs (above); Au-MPCs (below).

Since it was found that silver nanoparticles are capable of oncoming movement and coalescence inside a polyacrylate matrix (as a result of dipole–dipole attraction of polarized metal nanoparticles with permanently induced plasmon–polariton disturbances) [50], it can be assumed that the connection between the polymer matrix and the surface of nanoparticles is carried out due to a complex of labile electrostatic Coulomb and polarization van der Waals interactions.

Polymer composites derived from nanoparticles and bioelements are of significant theoretical and practical interest owing to the peculiarities of their structure and a wide range of pharmacological actions [49, 50, 51]. In particular, Zn polymer composite has extremely effective bactericidal, fungicidal, and bacteriostatic properties and exhibits wound healing and hemostatic effects [42]. The combination of a polymer and an inorganic nano-sized phase into a single material determines its exceptional properties and a wide range of pharmacological properties.

The high biological activity of polymer-metal complexes, including gold and silver ions, was a serious stimulus for the development of intensive research aimed at identifying their antitumor properties [52, 53, 54, 55]. The antitumor and cytotoxic activity of these drugs against some models of solid animal tumors in vivo and human tumor cell lines in vitro was established [56]. The study of the mechanism of action of auramacryl and argacryl included such aspects as studying the mechanism of cell death and the effect of compounds on the DNA structure of tumor cells. A significant place in these studies is occupied by gold-containing complex compounds, which are considered as promising experimental agents for the treatment of malignant tumors [57, 58, 59, 60].

3.1 Hemostatic activity of nanostructured metal polyacrylates

One of the most important principles of the function of new hemostatic agents based on nanostructured metal polyacrylates is their local action as a result of direct external local contact of the hemostatic agent and the wound site, which eliminates the entry of the hemostatic agent into the bloodstream and the associated threat of micro-clotting.

The screening of hemostatic activity and film-forming effect in all doses of aqueous solutions of new-generation hemostatics showed that they meet the basic requirements for local hemostatic agents. The biological activity of water-soluble metal-polymer composites (MPC) based on nanoparticles of noble metals and essential elements, as hemostatic agents, is determined by the structure of complementary protein molecule (primarily the predominant albumin). They are characterized by a unique nonspecific mechanism of hemostasis due to the ability to quickly form interpolymer complexes with blood plasma proteins, which does not affect the key parameters of hemostasis in the general bloodstream. There are no clotting factors involved, and there is no need for an enzymatic coagulation mechanism. Thanks to this, hemostatic agents of new generation are effective not only for normal, but also for pathological blood coagulation systems (anemia, hemophilia, Werlhof’s disease, afibrinogenemia, etc.). Of particular importance is hemostasis in case of von Willebrand disease (in patients all three parts of hemostasis are impaired). The hemostatic effect is achieved not only by protein denaturation, but by the formation of a film of the interpolymer complex due to the mechanism of specific cooperative interaction of macromolecules with complementary structures. The protective film, owing to its elasticity and plasticity, lines the wound bed in 5–10 seconds. It forms a durable, hermetic coating that adheres well to the wound surface to form a mechanical barrier to bleeding [41, 42, 43, 44, 45, 46, 47, 48].

The effect of different concentrations (1, 2, 5, 10% aqueous solutions) of noble metal- and bioelement-derived PMC on the rate of hemostasis and the film-formation was studied on Chinchilla rabbits (3–4 kg) under the conditions of thiopental anesthesia (2–4 ml of 0.1% thiopental solution intravenously, and then 6–10 ml of 0.1% solution intraperitoneally). Next, a laparotomy was performed using a longitudinal incision along the white line. Afterwards the intestine, limited with wipes moistened with warm saline, and the anterior surface of the liver were delivered into the wound. A superficial wound (about 1.5 cm2 of area and about 0.1 cm of depth) was applied to the liver using a sharp razor with a special limiter. The developed capillary-parenchymal bleeding was arrested by uniform application of PMC aqueous solution in different concentration to the entire area of the wound surface. Hemostasis with a gauze swab was used as a control.

The studied concentrations of lithium derivatives of PMC have different hemostatic activity. Thus, 5 and 10% solutions of lithium PMC, compared to the control, reduce the bleeding time by almost half (128 and 120 s, respectively, with the control being 277 s), a sufficiently dense and elastic film being formed, after removal of which bleeding does not resume.

Higher concentrations of PMC sodium solutions (2, 5, and 10%) increase the hemostatic effect to 129: 120: 87 s, which is 43%: 40%: 29% the 100% control time of hemostasis, respectively.

The solutions of PMC potassium salts exhibit similar hemostatic effect: a 1% solution (6.7 mg/cm² dose) stops bleeding for 133 s, while a 2% solution (13.4 mg/cm² dose) arrests bleeding for 134 s. A 5% solution (33.5 mg/cm² dose) reduces hemostasis for 106 s, whilst application of a 10% solution of PMC potassium (67 mg/cm² dose) to the wound surface stops the bleeding for 96 s.

It should be noted that when 1 and 2% solutions of potassium PMC are applied to the wound surface, a film is quickly formed, but its structure is very thin. At a higher concentration of PMC potassium solutions, the structure of the film coating becomes denser, the adhesive ability is improved, and re-bleeding does not occur.

About 5% PMC solution rubidium (dose 33.5 mg/cm²) has the best hemostatic effect (99 s or 43% of the control time). When this solution is applied to the wound surface, dome-shaped, very dense film is formed for 2 s that adheres well to the tissue. The spilling blood is located in the film reservoir, and after 20–30 s, the film is divided into layers, which leads to re-bleeding. In case of 2% PMC rubidium solution (dose 13.4 mg/cm²), the time of hemostasis is 128 s, and the film is formed slower (10 s). At a lower dose (6.7 mg/cm²), hemostasis and film formation are inhibited (155 and 15 s, respectively).

With the concentration of PMC cesium solutions increasing from 6.7 mg/cm² to 33.5 mg/cm², hemostatic activity is improved, and the time of hemostasis is reduced. For 1% PMC cesium solution (dose 6.7 mg/cm²), the time of hemostasis is decreased to 63% (147 s) as compared to the control group. In case of 2% PMC cesium solution (dose 13.4 mg/cm²), the duration of hemostasis is 54.1 ± 9.8% (128.6 ± 27.2 s). 5% solution (dose 33.5 mg/cm²) diminishes the time of hemostasis to 41.6 ± 7.7% (99.4 ± 18 s). The increase of the substance dose on the wound surface almost does not change the hemostatic activity, but leads to the formation of a denser, atraumatic film with good adhesive ability.

The polymer composites containing nanoparticles of noble metals, including gold, show high hemostatic activity. Thus, gold PMC can be considered as potential hemostatic agents [40, 48, 61]. The hemostatic potential of argacryl was studied in vitro using samples of both normal and abnormal blood. For this purpose, disorders of the hemostatic system were simulated. Deficiency of blood coagulation factors was reproduced by 2, 4, and 8 times dilution of donor blood plasma containing 4 g/l fibrinogen with a physiological solution. As a result, the amount of fibrinogen, which was determined by the photometric method, was 1.9, 1.2 and 0.5 g/l, respectively. Anticoagulant and fibrinolytic activity was modified by the addition of 25 and 5 IU of heparin, streptokinase, or imozymase to 1 ml of blood. The duration of blood coagulation was determined according to Lee–White procedure in minutes. It was established that argacryl had a hemostatic effect and can neutralize high concentrations of heparin, streptokinase, and imozymase, as well as sodium citrate [61]. Argacryl can be used clinically to arrest bleeding in cases of high anticoagulant and fibrinolytic activity [40, 47, 49, 62].

About 1, 2, and 5% cyacryl aqueous solutions form a film for 15 s with high adhesion to the wound surface and the hemostasis time of 191 ± 18, 199 ± 20, and 171 ± 20 s, respectively [42].

Metal-polymer composites based on nanoparticles of noble metals and essential elements with a wide range of biological activity can be used as universal agents. Innovative potential drugs derived from polymer composites can effectively solve the problems of emergency medicine as hemostatics. In addition, they not only provide rapid hemostasis, but also perform protective functions (closing the wound from external infection) providing an antibacterial effect.

3.2 Antimicrobial activity

The most important challenge of pharmaceutical sciences is the search, study, and practical application of relatively safe drugs exhibiting biological activity. Antimicrobial and antiseptic agents used in clinics negate their therapeutic efficiency over time due to the formation of microorganism-resistant species. As a consequence, the need for more effective, straightforward, environmentally benign, and inexpensive biocidal agents becomes an imperative for health care. In practical medicine, hemorrhage is very often complicated by the infections caused by microflora, which is highly resistant to modern antimicrobial drugs. In contrast to currently employed local hemostatic agents, new potential hemostatics containing no antibiotics in the structure have an effective antimicrobial action [41, 42, 47, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62]. They can perform protective functions (e.g., closing the wound from external infection) and exhibit antibacterial effects without antibiotics promoting the development of reparative regeneration processes up to complete epithelization of damaged tissue.

The antimicrobial activity of K, Rb, Cs, Zn, Ag, and Li + Cu PMC was screened in accordance with the requirements of the State Pharmacopeia using test microorganisms obtained from the State Collection of Pathogenic Microorganisms (L.A. Tarasevich Research Institute of Standardization and Control) and strains isolated from patients of a purulent-septic center with various surgical pathologies [63]. The test cultures were grown in a thermostat for 18–20 h on slope. Culture growth was washed off with warm sterile 0.5% solution of sodium chloride, standardized to 109 CFU/ml according to the turbidity standard, and diluted to a concentration of 103 CFU/ml using ten-fold serial dilutions.

Next, the corresponding preparation (1 ml) was added to two vials with 10 ml of thioglycollate medium and two vials with 10 ml of Sabouraud medium. Then 0.1 ml of microbial suspension was placed to each vial, and each microorganism was added separately. The cultures were incubated in thioglycollate medium at 35°C for 48 h and in Sabouraud’s medium at 20–25°C for 72 h. Test vials with nutrient media, into which, instead of diluting the drugs, a similar amount of distilled water was added, served as controls.

After the completion of the incubation, that is, after the appearance of growth of test microorganisms in control tubes without the preparation, the presence or absence of test strains growth on media, in which various dilutions of the tested substances were added, was noted.

The investigations showed that 5% aqueous solution of rubidium PMC exhibited antimicrobial activity: 29 tested cultures (80.5%) were sensitive to this composite. About 22 cultures (61%) were sensitive to 2% solution, and 14 cultures (38.9%) were sensitive to 1% solution.

About 19 cultures (52.7%) were sensitive to 5% aqueous solution of potassium PMC, 16 cultures (44.4%) were sensitive to 2% solution, and 11 cultures (30.5%) were sensitive to 1% solution. The potassium composite showed antimicrobial activity against only gram-negative microorganisms.

About 20 cultures (55.6%) were sensitive to 5% aqueous solution of cesium PMC, 14 cultures (38.9%) were sensitive to 2% solution, and 5 cultures (13.9%) were sensitive to 1% solution. The studied PMCs are efficient against enterococci, which are resistant to most modern antimicrobial agents.

An effective potential hemostatic agent based on Li and Cu PMC [42] has simultaneously high antimicrobial effect: among 36 cultures studied, 30 (83.3%) were sensitive to 5 and 2% aqueous solutions, 23 were sensitive to 1% solution (63.9%) cultures, resistant to aerobic gram-positive spore-forming bacteria Bacillus cereus, strains of gram-positive cocci Staphylococcus aureus ATCC.

The data obtained indicate that 5% aqueous solution of the partial potassium salt of PAA has a moderate antimicrobial effect, suppressing only 19 pathogenic microorganisms from 29 studied. Maximum antimicrobial activity is exhibited by 5% aqueous solutions of rubidium and cesium partial salts of PAA (they inhibit the growth of 29 and 21 microorganisms, respectively). It is noteworthy that until now the effective antimicrobial activity of polymer salts of rubidium and cesium was out of the research focus. It can be assumed that these salts can be employed not only as effective hemostatic agents, but also as antiseptics.

The antimicrobial activity of cyacryl was studied using 26 test strains of museum cultures (L.A. Tarasevich Research Institute of Standardization and Control) and multi-resistant strains isolated from patients of purulent-septic center. The effect of cyacryl was evaluated in accordance with the requirements of the State Pharmacopeia of the USSR [63]. For this purpose, a solution of cyacryl substance (1 ml) of the appropriate concentration (1, 2, 5%) was added to two vials with thioglycollate medium (10 ml) and two vials with Sabouraud medium (10 ml). A microbial suspension of the test strain (0.1 ml) containing 1000 cells in 1 ml was placed into the vials. Next, the cultures were incubated in thioglycollate medium at 35°C for 48 h, and in Sabouraud’s medium at 20–25°C for 72 h. The vials with nutrient media in distilled water were served as a control. It was established that 5% aqueous solution of cyacryl inhibited 22 of 26 studied strains of microorganisms.

The wound- and burn-healing effect of 5% aqueous solution of cyacryl was evaluated on models of experimental aseptic skin wounds and thermal burns of mice. The healing of skin wounds was studied on 20 white outbred mice of both sexes weighing 19–20 g using the Ponomarev–Astrakhantsev method. Depilation of the skin was carried out the day before the model was reproduced and wiped with 70% ethyl alcohol. Aseptic wounds were made by cutting out a full-thickness skin flap in the back area. In the control group, 0.1–0.2 ml of 0.9% aqueous solution of sodium chloride was applied to the wound; in the experimental group, a 5% aqueous solution of cyacryl was used. The wounds were treated immediately after the wound was made. Daily, throughout the experiment, applications without bandages were employed. The average values of the affected areas in the control and experimental groups were measured using the planimetric method, assuming rectangularity of these areas. The experimental data were processed using the standard variation statistics method. Complete healing of wounds was observed after 16.4 and 21 days in experimental and control groups, respectively. During the healing process, a sticky film was formed on the wound surface of the skin, under which there was a soft red surface that did not change its color for a long time. Inflammatory processes were not observed.

Thermal burns of outbred mice of both sexes (19–20 g) were induced by a special installation at 103–105°C with an exposure of 3 s. Similarly, in the control group, 0.1–0.2 ml of 0.9% aqueous solution of sodium chloride was applied to the burn wound; in the experimental group, 0.1–0.2 ml of a 5% aqueous solution of cyacryl was used. Treatment was also carried out immediately after a burn lesion of the skin. During the entire experiment, applications of saline solution and 5% aqueous solution of cyacryl without bandages were employed. The average values of burn areas were measured using the planimetric method. The healing process was characterized by the average diameter of the burn and the period of complete healing. The experimental data indicated that 5% aqueous solution of cyacryl significantly accelerated the repair regeneration of burn skin. At the same time, active epithelization of the burn surface edges was observed, and after 7–10 days, scab shedding occurred. Thus, 5% aqueous solution of cyacryl in experimental models with different damage to the skin integrity of animals exhibits wound- and burn-healing effects, the experimental group of animals being calmer than the control group throughout the experiment. This behavioral reaction obviously indicates the analgesic effect of cyacryl [42, 64].

The antibacterial activity of 5% aqueous solutions of argacryl was studied using 27 strains of microorganisms isolated from patients of the purulent-septic center and museum strains containing 1000 cells per 1 ml in thioglycolate and Sabouraud medium. The cultures were incubated at 35°C for 48 h and at 20–25°C for 72 h, respectively. Nutrient media in which distilled water was added instead of the studied preparations were served as a control.

It was found that 5% aqueous solution of argacryl suppressed all 27 types of pathogenic microorganisms. The studies of antimicrobial activity showed that 1% aqueous solution of argacryl inhibited gram-negative aerobic bacteria Proteus, E. coli 25922, the infectious agent of Pseudomonas aeruginosa, aerobic gram-positive spore-forming bacteria Bacillus cereus, the most pathogenic Staphylococcus aureus [49, 62].

4. Conclusions

The analysis of biological processes and the dependence of the functions of their components on the structure have allowed hemostatic agents of new generation to be designed. They have a unique mechanism of hemostasis, which is due to the specific interaction with the complementary structures of targets in the blood plasma, without affecting the key parameters of hemostasis in the general blood flow. In this case, it is possible to quickly stop bleeding in patients with disorders of the blood coagulation system.

Hemostatic agents of new generation based on metal-polymer composites containing nanoparticles of noble metals and micro-, macro-, and ultrabioelements possess a wide range of pharmacological activity. In terms of novelty, they have a high innovative potential and characteristics that allow them to be classified as new forms of synthetic drugs for medical purposes.

They can be successfully used for various types of injuries, expanding the scope of surgical interventions, increasing the number of patients with hemorrhagic manifestations due not only to the widespread application of anticoagulants and the introduction into medical practice of drugs that have a hepatotoxic effect, but also owing to an equally dangerous cause of hemorrhage: coagulation pathology of blood systems, in clinical and practical medicine, as well as in combat conditions and emergency medicine.

Screening of the pharmacological properties of MPC has shown a wide spectrum of their activities. MPs of heavy alkali metals (K, Rb, Cs) exhibit effective hemostatic properties. A study of the hemostatic activity of metal-polymer composites containing nanoparticles of noble metals, for example, gold (aurumacryl), shows high hemostatic activity and the possibility of using Au MPC as a hemostatic agent. It has been established that argacryl has a hemostatic effect and can neutralize high concentrations of heparin, streptokinase, and imozymase. Argacryl can be used clinically to stop bleedings, including those with high anticoagulant and fibrinolytic activity.

The screening of the antimicrobial activity of K, Rb, Cs, Zn, Ag, and Li + Cu PMC shows the maximum activity is observed for 5% aqueous solutions of Rb and Cs PMC. 5% aqueous solution of cyacryl inhibits 22 of 26 studied strains of microorganisms and has wound and burn healing and analgesic effects. It is found that 5% aqueous solution of argacryl suppresses all 27 types of pathogenic microorganisms under question. At the same time, it exerts biocidal action on gram-negative aerobic bacteria, causative agents of nosocomial infections, and aerobic gram-positive spore-forming bacteria, the most pathogenic, common, and dangerous microorganisms for humans.

The biological basis for the design of a new class of potential antitumor drugs has been developed. A comprehensive study of the antitumor activity of noble metal PMC (aurumacryl and argacryl) reveals that these potential antitumor agents have significant cytotoxic, antiproliferative, and antitumor activity.

Acknowledgments

We are grateful to N.V. Klushina for her help with illustrating.

Conflict of interest

The authors declare no conflict of interest.