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The ever-emerging environmental pollution as a result of the abuse of antibiotics and other pollutants has caused a serious threat to the ecological environment and human health. Therefore, development of effective strategies for degradation, as well as disposal of antibiotic residues in water is urgently needed. Antibiotics, such as penicillins, are extensively utilized for treatment of bacterial infections for humans and animals and have been spreading in water due to their extremely low metabolic rate. Immobilized ß-lactamase onto aminosilane magnetic nanoparticles (AMN-MNPs) was used for the degradation of penicillin (PEN). Thermal stability of such immobilized ß-lactamase was investigated, as well as enzyme kinetics of free ß-lactamase and immobilized ß-lactamase was determined. Degradation study of PEN was performed with free and immobilized ß-lactamase and analyzed using HPLC system. The obtained results show that immobilized ß-lactamase has many advantages compared to free ß-lactamase. The immobilized enzyme exhibited hyperactivation of the enzyme, resulting in 107 % residual activity with 100 % immobilization efficiency. Immobilized ß-lactamase showed good thermal stability at various temperatures above 40°C when compared to free ß-lactamase, which was inactivated when exposed to temperatures above 40°C. The results also suggest that the catalytic activity of immobilized ß-lactamase for the degradation of PEN has been significantly enhanced compared to free ß-lactamase, resulting in 98 % degradation of PEN, while only 22 % of PEN was degraded with the free enzyme after 24 hours.

Micellar structures from medicinal mushrooms are self-growing, fibrous, polymeric structures that can be successfully functionalized with various bioactive substances. Moreover, micellar structures can successfully mimic the extracellular matrix of human body tissues. Therefore, they can be used as novel biomaterials in tissue engineering and wound healing. On the other hand, fruit by-products, such as mango peels, are mainly discarded but represent a renewable source from which products with exceptional added value can be obtained. The aim of our study was to determine the antimicrobial properties of functionalized micellar structures obtained from medicinal mushrooms such as Ganoderma lucidum and Pleurotus ostreatus. The adsorption method was used to functionalize the micellar structures with natural mango peel extract (MPE) obtained by an ultrasound-assisted extraction method. In addition, the antimicrobial activity of the functionalized micellar structures was validated using a disk diffusion method. The results of our study show a successful functionalization of micellar structures with natural MPE with a loading efficiency of up to 50-60% and a release rate of 73-96%. Moreover, the antimicrobial properties of the micellar structures from the two selected medicinal mushrooms were successfully determined against the tested pathogenic microorganisms. Therefore, mycelium-based functional materials represent promising bio-composite materials, especially for biomedical applications.

Since various bioactive substances are unstable and can degrade in the gastrointestinal tract, their stabilization is crucial. This study aimed to encapsulate mango peel extract (MPE) into edible alginate beads using the ionotropic gelation method for the potential oral delivery of bioactive substances. Mango peels, generally discarded and environmentally harmful, are rich in health-promoting bioactive substances. The alginate beads were examined for entrapment efficiency, particle size, morphology, thermal stability, physiochemical interactions, release profile under gastrointestinal conditions, and antibacterial efficacy. The study demonstrated the successful encapsulation of MPE with an efficiency of 63.1%. The in vitro release study showed the stability of the alginate beads in simulated gastric fluid with a maximum release of 45.0%, and sustained, almost complete release (99.4%) in simulated intestinal fluid, indicating successful absorption into the human body. In both fluids, the MPE release followed first-order kinetics. Encapsulation successfully maintained the antibacterial properties of MPE, with significant inhibitory activity against pathogenic intestinal bacteria. This is the first study on MPE encapsulation in alginate beads, presenting a promising oral delivery system for high-added-value applications in the food industry for dietary supplements, functional foods, or food additives. Their production is sustainable and economical, utilizing waste material and reducing environmental pollution.

Plant waste materials are important sources of bioactive compounds with remarkable health-promoting benefits. In particular, industrial by-products such as mango peels are sustainable sources of bioactive substances, with antioxidant, enzymatic, and antimicrobial activity. Appropriate processing is essential to obtain highly bioactive compounds for further use in generating value-added products for the food industry. The objective of the study was to investigate and compare the biological activity of compounds from fresh and dried mango peels obtained by different conventional methods and unconventional extraction methods using supercritical fluids (SFE). The highest total phenolic content (25.0 mg GAE/g DW) and the total content of eight phenolic compounds (829.92 µg/g DW) determined by LC-MS/MS were detected in dried mango peel extract obtained by the Soxhlet process (SE). SFE gave the highest content of proanthocyanidins (0.4 mg PAC/g DW). The ethanolic ultrasonic process (UAE) provided the highest antioxidant activity of the product (82.4%) using DPPH radical scavenging activity and total protein content (2.95 mg protein/g DW). Overall, the dried mango peels were richer in bioactive compounds (caffeic acid, chlorogenic acid, gallic acid, catechin, and hesperidin/neohesperidin), indicating successful preservation during air drying. Furthermore, outstanding polyphenol oxidase, superoxide dismutase (SOD), and lipase activities were detected in mango peel extracts. This is the first study in which remarkable antibacterial activities against the growth of Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) were evaluated by determining the microbial growth inhibition rate after 12 and 24 h incubation periods for mango peel extracts obtained by different methods. Ethanolic SE and UAE extracts from dried mango peels resulted in the lowest minimum inhibitory concentrations (MIC90) for all bacterial species tested. Mango peels are remarkable waste products that could contribute to the sustainable development of exceptional products with high-added value for various applications, especially as dietary supplements.

The aim of this research was to identify and quantify biologically active compounds from avocado (Persea americana L.) seeds (AS) utilizing different techniques with the use of ultrasound (US), ethanol (EtOH), and supercritical carbon dioxide (scCO2) for possible applications in (bio)medicine, pharmaceutical, cosmetic, or other relevant industries. Initially, a study of the process efficiency (η) was carried out, which revealed yields in the range of 2.96–12.11 wt%. The sample obtained using scCO2 was found to be the richest in total phenols (TPC) and total proteins (PC), while the sample obtained with the use of EtOH resulted in the highest content of proanthocyanidins (PAC). Phytochemical screening of AS samples, quantified by the HPLC method, indicated the presence of 14 specific phenolic compounds. In addition, the activity of the selected enzymes (cellulase, lipase, peroxidase, polyphenol oxidase, protease, transglutaminase, and superoxide dismutase) was quantified for the first time in the samples from AS. Using DPPH radical scavenging activity, the highest antioxidant potential (67.49%) was detected in the sample obtained with EtOH. The antimicrobial activity was studied using disc diffusion method against 15 microorganisms. Additionally, for the first time, the antimicrobial effectiveness of AS extract was quantified by determination of microbial growth-inhibition rates (MGIRs) at different concentrations of AS extract against three strains of Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas fluorescens) bacteria, three strains of Gram-positive (Bacillus cereus, Staphylococcus aureus, and Streptococcus pyogenes) bacteria, and fungi (Candida albicans). MGIRs and minimal inhibitory concentration (MIC90) values were determined after 8 and 24 h of incubation, thus enabling the screening of antimicrobial efficacy for possible further applications of AS extracts as antimicrobial agents in (bio)medicine, pharmaceutical, cosmetic, or other industries. For example, the lowest MIC90 value was determined for B. cereus after 8 h of incubation in the case of UE and SFE extracts (70 μg/mL), indicating an outstanding result and the potential of AS extracts, as the MIC values for B. cereus have not been investigated so far.

Proper processing of natural material is crucial to obtain an extract with high content of biologically active components. Dried, grinded ginger roots were extracted by ultrasonic method and supercritical extraction with CO2. The aim of the study was to determine if a mixture of the two types of extracts attained by different methods and solvents exhibits better bioavailability than each extract itself. Therefore, both extracts were analytically evaluated and then mixed in a ratio of 1:1. The supercritical extract (SCG extract) and the mixed extract (mixG extract) had high antioxidant activity (78% and 73%) and total phenols (827 mg/g ext. and 1455 mg/g ext.), which is also consistent with the levels of gingerol (303 mg/g ext. and 271 g/g ext.) and shogaol (111 mg/g ext. and 100 g/g ext.) in the extracts. In comparison to both pure extracts higher levels of total phenols were found in the extract mixG. This could be the reason for the significant inhibition of melanoma cells and antimicrobial potential (against Staphylococcus aureus, Escherichia coli, and Candida albicans). The combination of the extracts resulted in a significant increase in the inhibition of selected microbial and melanoma cells WM-266-4 compared to the control. Cell viability decreased below 60% when mixG extract was applied. Antimicrobial activity has been confirmed.

This study is focused on different extractions (Cold Maceration (CM), Ultrasonic Extraction (UE), Soxhlet Extraction (SE) and Supercritical Fluid Extraction (SFE)) of bioactive compounds from pomegranate (Punica Granatum L.) fruit peels using methanol, ethanol, and acetone as solvents in conventional extractions and changing operating pressure (10, 15, 20, 25 MPa) in SFE, respectively. The extraction yields, total phenols (TP) and proanthocyanidins (PAC) contents, and antioxidant activity of different extracts are revealed. TP and PAC recovered by extracts ranged from 24.22 to 42.92 mg gallic acid equivalents (GAE)/g and 2.01 to 5.82 mg PAC/g, respectively. The antioxidant activity of extracts ranged from 84.70% to 94.35%. The phenolic compound identification and quantification in selective extracts was done using the LC-MS/MS method. The contents of different flavonoids and phenolic acids have been determined. SFE extract, obtained at 20 MPa, contained the highest content (11,561.84 μg/g) of analyzed total polyphenols, with predominant ellagic acid (7492.53 μg/g). For the first time, Microbial Growth Inhibition Rates (MGIRs) were determined at five different concentrations of pomegranate SFE extract against seven microorganisms. Minimal Inhibitory Concentration (MIC90) was determined as 2.7 mg/mL of SFE pomegranate peel extract in the case of five different Gram-negative and Gram-positive bacteria.

Recently, the use of Aloe species has become very widespread. These are extensively used as a nutraceutical in a variety of health care products and food supplements. In addition, the occurrence of the quickly adaptable microorganisms, particularly bacteria, which can develop resistance to antibiotics, is a major problem for public health, and therefore, it is necessary to search for new antimicrobials. In our study, the content of total phenols, proanthocyanidins, and proteins in fresh and lyophilized samples of A. arborescens and A. barbadensis and their ethanol extracts was investigated. Furthermore, enzymatic and antioxidant activity of samples were studied. Since antimicrobial activity of fresh samples was determined in our latest research, a more detailed study of antimicrobial effectiveness of A. arborescens and A. barbadensis (lyophilized, extracts) was performed. Ethanol extracts in particular contain higher concentrations of bioactive substances and show the topmost antioxidant activity. The novelty of the study refers to the observation of industrially important enzyme activities such as α-amylase, cellulase, lipase, peroxidase, protease, and transglutaminase in the samples as well as the microbial growth inhibition rates determination (MGIR) at different concentrations of added aloe samples. All samples inhibited the growth of all tested microbial cells. MIC90 for A. arborescens and A. barbadensis were also determined in case of B. cereus, P. aeruginosa, P. fluorescens, and S. aureus. The results of our study tend to give credence to the popular use of both aloes in medicine and in the cosmetic, food, and pharmaceutical industries.

Due to the growing awareness of Punica granatum fruit’s health-promoting properties, the pomegranate is increasingly used for food purposes. This results in the formation of biological waste products such as peels. A biowaste circular bioeconomy strategy holds great prospective for a sustainable economy. Therefore, a sustainable and environmentally friendly way of disposing of waste (e.g., use of biowaste to obtain high-value components (e.g., punicalagins, enzymes)) is crucial for the protection of the environment and human health. In the presented study, the content of total phenols and proanthocyanidins in ten samples of Punica granatum fruit (juice, aqueous (H2O) and ethanolic (EtOH) extracts of peels and seeds) was determined. Peel extracts were found to be the richest in the content of secondary metabolites and showed extremely high antioxidant potential (approximately 90% inhibition: DPPH radical scavenging activity). To the best of our knowledge, this is the first comparative study to determine the enzymatic activity of α-amylase, lipase, peroxidase, protease, and transglutaminase in different P. granatum samples. Furthermore, the antibacterial efficacy of all P. granatum samples was qualitatively determined against three strains of Gram-negative (Escherichia coli, Pseudomonas aeruginosa, and Pseudomonas fluorescens) and three strains of Gram-positive (Bacillus cereus, Staphylococcus aureus, and Streptococcus pyogenes) bacteria, susceptible to gaining antibiotic resistance. Moreover, the most promising peel extracts were quantified for antibacterial efficacy against tested bacteria at five different concentrations. All samples slowed down and inhibited the growth of all tested bacteria. MIC90 values (2.7 or 0.3 mg/mL) were determined in 18 out of 24 experiments (four samples, six bacteria tested). There is no research in the reviewed literature that is current with such detailed and comprehensive determination of P. granatum peel extracts antibacterial activity. The results of the research showed great potential for the use of P. granatum in the field of antibacterial activity in biomedicine applications and in the cosmetic, food, and pharmaceutical industries.

Nowadays, there are many commercial products from natural resources on the market, but they still have many additives to increase their biological activities. On the other hand, there is particular interest in natural sources that would have antimicrobial properties themselves and would inhibit the growth and the reproduction of opportunistic microorganisms. Therefore, a comparative antimicrobial study of natural samples of aloe and its commercial products was performed. Qualitative and quantitative determination of antimicrobial efficiency of Aloe arborescens and Aloe barbadensis and its commercial products on fungi, Gram-negative, and Gram-positive bacteria was performed. Samples exhibited antimicrobial activity and slowed down the growth of all tested microorganisms. Research has shown that natural juices and gels of A. arborescens and A. barbadensis are at higher added concentrations comparable to commercial aloe products, especially against microbial cultures of Bacillus cereus, Candida albicans, and Pseudomonas aeruginosa, whose growths were completely inhibited at a microbial concentration of 600 μg/mL. Of particular importance are the findings of the good antimicrobial efficacy of fresh juice and gel of A. arborescens on tested microorganisms, which is less known and less researched. These results show great potential of A. arborescens for further use in medicine, cosmetics, food, and pharmaceutical industries.

Background: Bionanotechnology, as a tool for incorporation of biological molecules into nanoartifacts, is gaining more and more importance in the field of food packaging. It offers an advanced expectation of food packaging that can ensure longer shelf life of products and safer packaging with improved food quality and traceability. Scope and approach: This review recent focuses on advances in food nanopackaging, including bio-based, improved, active, and smart packaging. Special emphasis is placed on bio-based packaging, including biodegradable packaging and biocompatible packaging, which presents an alternative to most commonly used non-degradable polymer materials. Safety and environmental concerns of (bio)nanotechnology implementation in food packaging were also discussed including new EU directives. Conclusions: The use of nanoparticles and nanocomposites in food packaging increases the mechanical strength and properties of the water and oxygen barrier of packaging and may provide other benefits such as antimicrobial activity and light-blocking properties. Concerns about the migration of nanoparticles from packaging to food have been expressed, but migration tests and risk assessment are unclear. Presumed toxicity, lack of additional data from clinical trials and risk assessment studies limit the use of nanomaterials in the food packaging sector. Therefore, an assessment of benefits and risks must be defined.

The current study examines the effect of tannins and tannin extracts on the lag phase duration, growth rate, and generation time of Escherichia coli. Effects of castalagin, vescalagin, gallic acid, Colistizer, tannic acid as well as chestnut, mimosa, and quebracho extracts were determined on E. coli’s growth phases using the broth microdilution method and obtained by turbidimetric measurements. E. coli responds to the stress caused by the investigated antimicrobial agents with reduced growth rates, longer generation times, and extended lag phases. Prolongation of the lag phase was relatively small at low tannin concentrations, while it became more pronounced at concentrations above half the MIC. Moreover, for the first time, it was observed that lag time extensions follow a strict exponential relationship with increasing tannin concentrations. This feature is very likely a direct consequence of the tannin complexation of certain essential ions from the growth medium, making them unavailable to E. coli for its growth.

In this study the effect of growth medium strength on the minimum inhibitory concentration (MIC) of different tannins and tannin extracts against Escherichia coli was systematically investigated for the first time. Three pure compounds (vescalagin, castalagin and gallic acid) and five extracts (chestnut, quebracho, mimosa, Colistizer and tannic acid) were studied. Broth microdilution was assayed and bacteria were grown using different growth medium strengths varying from half to double the concentration recommended by the producer. MICs were determined using the iodonitrotetrazolium chloride (INT) dye or turbidity measurements. It was observed that MIC values depend on the growth medium strength. With an increase in the growth medium concentration MIC values rose roughly linearly for all samples, while their relative order remained unchanged, indicating that a direct interaction of tannins with growth medium nutrients represents the likely source of their antimicrobial activity. Understanding the effect of growth medium strength can finally yield a plausible explanation for the observed variation in MIC values reported in the scientific literature as well as provide help in planning proper applications of tannins in the livestock production.

Nano-scale lipid vesicles or liposomes are extremely important lipid particles because of their unique properties and possible incorporation of various biologically active substances into their interior. Therefore, they can be used for numerous biomedical applications. Liposomes have the ability to protect incorporated bioactive substances, thereby preserving their function. They have a significant advantage over various nanoparticles, as they can bind and transfer hydrophobic, hydrophilic, and amphiphilic compounds. The aim of the study was the synthesis of liposomes, suitable for the potential encapsulation of active ingredients for pharmaceutical and clinical purposes. Liposomes were prepared using a thin lipid film hydration method with glass beads. The synthesized liposomes were characterized by measuring the zeta potential to determine their stability, polydispersity index, and particle size. Furthermore, the biologically active ingredient gallic acid (GA) was incorporated into the lipid vesicles at different concentrations. The encapsulation efficiency of the active ingredient GA in liposomes and the in vitro release of the encapsulated bioactive component were studied using the dialysis technique. Synthesized nano-scale lipid vesicles were found to be stable, with an average size of 181.5 nm. The highest encapsulation efficiency (98.3%) and the highest percentage of released bioactive substance (38.3%) were obtained at 0.1 mg/mL of GA. GA-incorporated nano-scale lipid vesicles are promising as suitable carriers of bioactive ingredients for various therapeutic purposes.

Heavy metals being the most common pollutants of water and soil pose a risk for the ecosystems due to their non-degradable nature. Especially, chromium (Cr) is widely used in metal plating, pigmentation, printing, textile dyeing, wood preservation and other industries, therefore being a very common pollutant in surface and underground waters. The elimination of such pollutants from wastewater is highly important because of their carcinogenic and toxic nature. Among many methods for the removal of Cr(VI) ions from wastewater, adsorption is the most common and effective physiochemical method, because of its high efficiency, recyclability, cost-effectiveness and simplicity. Polysaccharides have been extensively employed in synthesis of magnetic nanoparticles (MNPs) as coating materials for constructing an adsorptive material, mainly due to their high adsorptive ability and low-cost. They are also environmentally friendly, renewable, biodegradable, biocompatible and can easily be modified. Arabinogalactan (AG) is a polysaccharide, that has high adsorption capacity for Cr(VI) ions. AG modified magnetic nanoparticles (AG-MNPs) were prepared by co-precipitation method using ferric and ferrous ions and later used as the adsorptive material for efficient Cr(VI) removal. The optimum conditions for Cr(VI) ions adsorption were found to be at pH 4, with contact period of only 30 min at 200 rpm, resulting in 92.9% adsorption efficiency and 99.6% maximum adsorption efficiency after 120 min at 200 rpm, using Cr(VI) ions at concentration of 0.5, 1.0 and 5.0 mg/L.

Enzyme-catalyzed processes are currently a powerful tool in the chemical industry due to the reduction of process time, specificity, eco-friendly characteristics, intake of low energy input, lower cost and nontoxic properties. Laccases are versatile enzymes, which catalyze oxidation reactions coupled to four-electron reduction of molecular oxygen to water. Laccases are used for decolorization and detoxification of industrial effluents and are widely used in wastewater treatment. For improving enzyme utilization in biotechnological processes, the process cost has to be reduced, the enzyme stability during industrial processes should be enhanced and the recycle and reuse step should be favorable. The immobilization of the enzyme is an important step for enhancing enzyme catalytic properties and operational stability. In our study, two different types of immobilization were used for laccase: cross-linked enzyme aggregates (CLEA) and magnetic cross-linked enzyme aggregates (mCLEA). The enzyme activity of synthesized CLEA was 0.237 U/mg laccase and mCLEA 0.637 U/mg laccase, respectively. In the next step, immobilized laccase in the form of CLEA and mCLEA was treated under supercritical conditions. Supercritical fluids (SCFs) comprise a unique class of nonaqueous media for biocatalysis and bioseparation. It is very difficult (almost impossible) to predict the stability and activity of an enzyme in any SCF at a certain pressure. Therefore, the stability of both laccase immobilized forms in supercritical carbon dioxide (SC CO2) at different pressures was studied. The highest residual activity for both laccase immobilized forms were obtained after exposure to SC CO2 at 20 MPa, 35 °C for 5 h. The obtained residual activities were 145 ± 3 % for mCLEA and 128 ± 3 % for CLEA. Improved stability of immobilized laccase in the form of CLEA and mCLEA after SC CO2 treatment indicates the possibility of using laccase in supercritical media. Further application of CLEA laccase and mCLEA laccase could be reflected in the field of hospital wastewater treatment for removal of drugs.

For improving enzyme utilization in biotechnological processes, process costs have to be reduced, enzyme stability during industrial processes should be enhanced, and the recycle and reuse step should be favorable. The immobilization of enzymes is an important step for enhancing enzyme catalytic properties and operational stability. In order to reduce the costs of immobilization and consequently the cost of processes, a cheaper carrier (e.g. materials reclaimed as by-products) should be used. To achieve this, cellulase from Trichoderma sp. was immobilized on biochar obtained by low temperature hydrothermal carbonization (LTHTC) in two ways: by adsorption and by covalent binding via a crosslinking agent. The effect of immobilization time, enzyme concentration, type and concentration of the crosslinking agent and the types of carrier - biochar (LTHTC of waste from olive oil production (LTHTC of OL waste) or LTHTC of cellulose) on the immobilization efficiency and the residual activity of biocatalyst was studied. Higher immobilization efficiency and residual enzyme activity was achieved when the enzyme was covalently bound to biochar obtained by LTHTC of cellulose.

To study the release patterns of protein bovine serum albumin (BSA), porous poly(ε-caprolactone)-chitosan scaffolds with entrapped BSA were fabricated by using supercritical CO2 (scCO2) for its potential use in tissue engineering applications. An emulsion, consisting of a polymer-solvent solution and buffer protein solution was saturated with scCO2 at 12 MPa and 37 °C and then rapidly depressurized through a release valve causing bubble nucleation and precipitation of the composite material. The controlled total protein release from biodegradable poly(ε-caprolactone) with 5% chitosan (w/w) scaffolds was assessed by Bradford protein assay. After 16 to 20 days of protein release testing, 58.8% of the protein was released from composite with PCL (Mw=10,000 g/mol) and 43.9% from composite with PCL (Mw=60,000 g/mol). Preliminary studies for characterization of the prepared composite biomaterials using FTIR spectra, ESEM photo analysis and DSC analysis have been carried out.

Trimatostroma salinum, Wallemia ichthyophaga, Hortaea werneckii and Phaeotheca triangularis are halophilic fungi, which can thrive in a wide range of salinity. They present a source of valuable bioactive compounds, enzymes and proteins interesting for food and pharmaceutical industry. To separate enzymes from halophilic fungi cells, the mechanical method was used. Obtained results and new findings are important from the biotechnological point of view, since the separation of in the form of cocktail from halophilic fungi is interesting for industrial applications, especially for cascade reactions. Enzymes from extremophiles namely possess improved properties and can be used at harsh conditions where non-extremophilic enzymes may deactivate.

Composites of polyolefin matrices (HDPE and PP) were prepared by melt processing using two commercially available nano ZnO powders (Zinkoxyd aktiv and Zano 20). The mechanical and thermal properties, UV-Vis stability, and antibacterial activity of composites were studied. Tensile testing revealed that both nano ZnO types have no particular effect on the mechanical properties of HDPE composites, while some positive trends are observed for the PP-based composites, but only when Zano 20 was used as a nanofiller. Minimal changes in mechanical properties of composites are supported by an almost unaffected degree of crystallinity of polymer matrix. All polyolefin/ZnO composites exposed to artificial sunlight for 8−10 weeks show more pronounced color change than pure matrices. This effect is more evident for the HDPE than for the PP based composites. Color change also depends on the ZnO concentration and type; composites with Zano 20 show more intense color changes than those prepared with Zinkoxyd aktiv. Results of the antibacterial properties study show very high activity of polyolefin/ZnO composites against Staphylococcus aureus regardless of the ZnO surface modification, while antibacterial activity against Escherichia coli shows only the composites prepared with unmodified ZnO. This phenomenon is explained by different membrane structure of gram-positive (S. aureus) and gram-negative (E. coli) bacteria.

Chitosan-based nanomaterials have attracted significant attention in the biomedical field because of their unique biodegradable, biocompatible, non-toxic, and antimicrobial nature. Multiple perspectives of the proposed antibacterial effect and mode of action of chitosan-based nanomaterials are reviewed. Chitosan is presented as an ideal biomaterial for antimicrobial wound dressings that can either be fabricated alone in its native form or upgraded and incorporated with antibiotics, metallic antimicrobial particles, natural compounds and extracts in order to increase the antimicrobial effect. Since chitosan and its derivatives can enhance drug permeability across the blood-brain barrier, they can be also used as effective brain drug delivery carriers. Some of the recent chitosan formulations for brain uptake of various drugs are presented. The use of chitosan and its derivatives in other biomedical applications is also briefly discussed.

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