New photosensitive nanometric graphite oxide composites as antimicrobial material with prolonged action

Advances in bioinspired nanomaterials managing microbial biofilms and virulence: A critical analysis

Microbial virulence and biofilm formation stand as a big concern against the goal of achieving a green and sustainable future. Microbial pathogenesis is the process by which the microbes (bacterial, fungal, and viral) cause illness in their respective host organism. 'Nanotechnology' is a state-of-art discipline to address this problem. The use of conventional techniques against microbial proliferation has been challenging against the environment. To tackle this problem, there has been a revolution in this multi-disciplinary field, to address the aspect of bioinspired nanomaterials in the antibiofilm and antimicrobial sector. Bioinspired nanomaterials prove to be a potential antibiofilm and antimicrobial agent as they are non-hazardous to the environment and mostly synthesized using a single-step reduction protocol. They exhibit synergistic effects against bacterial, fungal, and viral pathogens and thereby, control the virulence. In this literature review, we have elucidated the potential of bioinspired nanoparticles as well as nanomaterials as a promising anti-microbial treatment pedagogy and throw light on the advancements in how smart photo-switchable platforms have been designed to exhibit both bacterial releasing as well as bacterial-killing properties. Certain limitations and possible outcomes of these bio-based nanomaterials have been discussed in the hope of achieving a green and sustainable ecosystem.

Biological Performance of Hexadeca-Substituted Metal Phthalocyanine/Reduced Graphene Oxide Nanobioagents

This study presents a tetra-substituted phthalonitrile derivative, namely, diethyl 2-(3,4-dicyano-2,5-bis(hexyloxy)-6-(4-(trifluoromethoxy)phenoxy)phenyl)malonate (a), cyclotetramerizing in the presence of some metal salts. The resultant hexadeca-substituted metal phthalocyanines [M= Co, Zn, InCl)] (b-d) were used for the modification of reduced graphene oxide for the first time. The effect of the phthalonitrile/metal phthalocyanines on biological features of reduced graphene oxide (rGO) was extensively examined by the investigation of antioxidant, antimicrobial, DNA cleavage, cell viability, and antibiofilm activities of nanobioagents (1-4). The results were compared with those of unmodified rGO (nanobioagent 5), as well. Modification of reduced graphene oxide with the synthesized compounds improved its antioxidant activity. The antioxidant activities of all the tested nanobioagents also enhanced as the concentration increased. The antibacterial activities of all the nanobioagents improved by applying the photodynamic therapeutic (PDT) method. All the phthalonitrile/phthalocyanine-based nanobioagents (especially phthalocyanine-based nanocomposites) exhibited DNA cleavage activities, and complete DNA fragmentation was observed for nanobioagents (1-4) at 200 mg/L. They can be used as potent antimicrobial and antimicrobial photodynamic therapy agents as well as Escherichia coli microbial cell inhibitors. As a result, the prepared nanocomposites can be considered promising candidates for biomedicine.

Recent advances and mechanism of antimicrobial efficacy of graphene-based materials: a review

Graphene-based materials have undergone substantial investigation in recent years owing to their wide array of physicochemical characteristics. Employment of these materials in the current state, where infectious illnesses caused by microbes have severely damaged human life, has found widespread application in combating fatal infectious diseases. These materials interact with the physicochemical characteristics of the microbial cell and alter or damage them. The current review is dedicated to molecular mechanisms underlying the antimicrobial property of graphene-based materials. Various physical and chemical mechanisms leading to cell membrane stress, mechanical wrapping, photo-thermal ablation as well as oxidative stress exerting antimicrobial effect have also been thoroughly discussed. Furthermore, an overview of the interactions of these materials with membrane lipids, proteins, and nucleic acids has been provided. A thorough understanding of discussed mechanisms and interactions is essential to develop extremely effective antimicrobial nanomaterial for application as an antimicrobial agent.

Graphical abstract

Novel bioactive dental restorations to inhibit secondary caries in enamel and dentin under oral biofilms

OBJECTIVE

To provide the first review on cutting-edge research on the development of new bioactive restorations to inhibit secondary caries in enamel and dentin under biofilms. State-of-the-art bioactive and therapeutic materials design, structure-property relationships, performance and efficacies in oral biofilm models.

DATA, SOURCES AND STUDY SELECTION

Researches on development and assessment new secondary caries inhibition restorations via in vitro and in vivo biofilm-based secondary caries models were included. The search of articles was carried out in Web of Science, PubMed, Medline and Scopus.

CONCLUSIONS

Based on the found articles, novel bioactive materials are divided into different categories according to their remineralization and antibacterial biofunctions. In vitro and in vivo biofilm-based secondary caries models are effective way of evaluating the materials efficacies. However, new intelligent and pH-responsive materials were still urgent need. And the materials evaluation should be performed via more clinical relevant biofilm-based secondary caries models.

CLINICAL SIGNIFICANCE

Secondary caries is a primary reason for dental restoration failures. Biofilms produce acids, causing demineralization and secondary caries. To inhibit dental caries and improve the health and quality of life for millions of people, it is necessary to summarize the present state of technologies and new advances in dental biomaterials for preventing secondary caries and protecting tooth structures against oral biofilm attacks. In addition, suggestions for future studies are provided.

Benefits of Usage of Immobilized Silver Nanoparticles as Pseudomonas aeruginosa Antibiofilm Factors

The aim of this study was to assess the beneficial inhibitory effect of silver nanoparticles immobilized on SiO2 or TiO2 on biofilm formation by Pseudomonas aeruginosa-one of the most dangerous pathogens isolated from urine and bronchoalveolar lavage fluid of patients hospitalized in intensive care units. Pure and silver doped nanoparticles of SiO2 and TiO2 were prepared using a novel modified sol-gel method. Ten clinical strains of P. aeruginosa and the reference PAO1 strain were used. The minimal inhibitory concentration (MIC) was determined by the broth microdilution method. The minimal biofilm inhibitory concentration (MBIC) and biofilm formation were assessed by colorimetric assay. Bacterial enumeration was used to assess the viability of bacteria in the biofilm. Silver nanoparticles immobilized on the SiO2 and TiO2 indicated high antibacterial efficacy against P. aeruginosa planktonic and biofilm cultures. TiO2/Ag0 showed a better bactericidal effect than SiO2/Ag0. Our results indicate that the inorganic compounds (SiO2, TiO2) after nanotechnological modification may be successfully used as antibacterial agents against multidrug-resistant P. aeruginosa strains.

Liquid “Syngas” Based on Supercritical Water and Graphite Oxide/TiO2 Composite as Catalyst for CO2 to Organic Conversion

The conversion of carbon monoxide into organic substances is one of the top topics of modern science due to the development of industry and the climate changes caused by it on the one hand, and the possibility of obtaining an economic effect on the other, as it could allow for partial recovery of fuels. A problem in this regard has always been the low solubility of CO2 in water, which eliminated the possibility of easy converting carbon dioxide into the liquid. The development of research on water critical states revealed the fact that water in a subcritical state has a much higher ability to dissolve gases. And this effect was used to obtain the "liquid synthesis gas" model presented in this paper. Equally important was the selection of an appropriate catalyst that would increase the efficiency of the conversion process by generating hydrogen in the system under the influence of cold plasma. In this work we present the studies of transformation of CO2 dissolved in supercritical water using partially reduced graphite oxide—nanometric titania composite (RGO-TiO2) as catalyst, due to the ability of RGO to generate hydrogen in the water environment (water splitting) under the influence of various physical factors, especially cold plasma. The RGO catalyst was stabilized with titanium oxide to obtain higher activity at lower RGO concentrations in the system. Therefore, research on conversions was preceded by a thorough analysis of CO2 solubility in supercritical water, as well as an analysis of the structural, morphological, and spectroscopic properties of the catalyst.

Graphic Abstract

General scheme of cold plasma reactor.

GO-based antibacterial composites: Application and design strategies

Graphene oxide (GO), for its unique structure with high biocompatibility and designability, is widely used in the antibacterial field. Various strategies have been designed to fabricate GO-based composites with antibacterial properties. This review summarized these strategies, divided them into three types and interpreted their antibacterial mechanisms: (i) "GO*/non-GO" type in which GO acts as the single antibacterial core, (ii) "GO*/non-GO*" type in which GO and non-GO components function synergistically as dual antibacterial cores, (iii) "GO/non-GO*" type in which non-GO acts as the single antibacterial core, while GO component plays a supportive, not a dominant role in antibiosis. Besides, the fields suiting their applications and factors influencing their antibacterial properties were analyzed. Finally, the limitations and prospects in the current researches were discussed. In summary, GO-based composites have revolutionized antibacterial strategies. This review may serve as a reference to inspire further research on GO-based antibacterial composites.

Composites based on graphite oxide and zirconium phthalocyanines with aromatic amino acids as photoactive materials

This article is a part of a scientific project focused on obtaining a new type of composite materials that are characterized by singlet oxygen generation upon irradiation with red light, which can be used as antibacterial agents. The composite material is nanoscale graphite oxide (GO) particles covalently bonded to an axially substituted zirconium phthalocyanine complex. For this purpose, two phthalocyanine zirconium complexes, axially mono-substituted with 4-aminosalicylic or 4-aminophthalic acids, were prepared and measured in terms of structure, morphology, and spectroscopic properties. The zirconium phthalocyanines are photosensitizers, and the axial ligands are bridging links connecting the complexes to the GO carrier (due to their terminal amino groups and carboxyl groups, respectively). The axial ligand in zirconium phthalocyanine complexes has a strong influence on the stability and optical properties of composite materials and, consequently, on reactive oxygen species (ROS) generation. In this paper, the effect of composite components (4-aminophthalato or 4-aminosalicylato substituted zirconium phthalocyanine complex as a photosensitizer and graphite oxide as a carrier and modulator of the action of active components) on ROS generation for potential antibacterial use is discussed.

The Impact of Graphite Oxide Nanocomposites on the Antibacterial Activity of Serum

Nanoparticles can interact with the complement system and modulate the inflammatory response. The effect of these interactions on the complement activity strongly depends on physicochemical properties of nanoparticles. The interactions of silver nanoparticles with serum proteins (particularly with the complement system components) have the potential to significantly affect the antibacterial activity of serum, with serious implications for human health. The aim of the study was to assess the influence of graphite oxide (GO) nanocomposites (GO, GO-PcZr(Lys)2-Ag, GO-Ag, GO-PcZr(Lys)2) on the antibacterial activity of normal human serum (NHS), serum activity against bacteria isolated from alveoli treated with nanocomposites, and nanocomposite sensitivity of bacteria exposed to serum in vitro (using normal human serum). Additionally, the in vivo cytotoxic effect of the GO compounds was determined with application of a Galleria mellonella larvae model. GO-PcZr(Lys)2, without IR irradiation enhance the antimicrobial efficacy of the human serum. IR irradiation enhances bactericidal activity of serum in the case of the GO-PcZr(Lys)2-Ag sample. Bacteria exposed to nanocomposites become more sensitive to the action of serum. Bacteria exposed to serum become more sensitive to the GO-Ag sample. None of the tested GO nanocomposites displayed a cytotoxicity towards larvae.

Turning Photons into Drugs: Phthalocyanine-Based Photosensitizers as Efficient Photoantimicrobials

One of the most promising alternatives for treating bacterial infections is antimicrobial photodynamic therapy (aPDT), making the synthesis and application of new photoactive compounds called photosensitizers (PS) a dynamic research field. In this regard, phthalocyanine (Pc) derivatives offer great opportunities due to their extraordinary light-harvesting and tunable electronic properties, structural versatility, and stability. This Review, rather than focusing on synthetic strategies, intends to overview current progress in the structural design strategies for Pcs that could achieve effective photoinactivation of microorganisms. In addition, the Review provides a concise look into the recent developments and applications of nanocarrier-based Pc delivery systems.

Light-Activated Zirconium(IV) Phthalocyanine Derivatives Linked to Graphite Oxide Flakes and Discussion on Their Antibacterial Activity

In search of an effective antibacterial agent that is useful in photodynamic therapy, new derivatives of zirconium(IV) phthalocyanine (ZrPc) complexes were obtained and linked to graphite oxide flakes. In the syntheses of ZrPc derivatives, two bis-axially substituted ligands with terminal amino group and different lengths of linear carbon chain (C4 in 4-aminobutyric acid or C11 in 11-aminoundecanoic acid) were used. The optical properties (absorption and photoluminescence spectra) of ZrPcs and the composites were examined. Broadband red–near-infrared lamp was tested as an external stimulus to activate ZrPcs and the composites. Optical techniques were used to show generation of singlet oxygen during irradiation. Considering the application of graphite oxide-based materials as bacteriostatic photosensitive additives for endodontic treatment of periapical tissue inflammation, the antibacterial activity was determined on one Escherichia coli strain isolated directly from an infected root canal of a human tooth and one strain with silver and antibiotic resistance. Looking at the obtained results, modified levels of activity toward different bacterial strains are discussed.

Ag and Au nanoparticles/reduced graphene oxide composite materials: Synthesis and application in diagnostics and therapeutics

The exceptional electrical, thermal, optical and mechanical properties have made two dimensional sp² hybridized graphene a material of choice in both academic as well as industrial research. In the last few years, researchers have devoted their efforts towards the development of graphene/polymer, graphene/metal nanoparticle and graphene/ceramic nanocomposites. These materials display excellent mechanical, electrical, thermal, catalytic, magnetic and optical properties which cannot be obtained separately from the individual components. Fascinating physical and chemical properties are displayed by noble metal nanomaterials and thus they represent model building blocks for modifying nanoscale structures for diverse applications extending from catalysis, optics to nanomedicine. Insertion of noble metal (Au, Ag) nanoparticles (NPs) into chemically derived graphene is thus of primary importance to open new avenues for both materials in various fields where the specific properties of each material act synergistically to provide hybrid materials with exceptional performances. This review attempts to summarize the different synthetic procedures for the preparation of Ag and Au NPs/reduced graphene oxide (rGO) composites. The synthesis processes of metal NPs/rGO composites are categorised into in-situ and ex-situ techniques. The in-situ approach consists of simultaneous reduction of metal salts and GO to obtain metal NPs/rGO nanocomposite materials, while in the ex-situ process, the metal NPs of desired size and shape are first synthesized and then transferred onto the GO or rGO matrix. The application of the Ag NPs and Au NPs/rGO composite materials in the area of biomedical (drug delivery and photothermal therapy) and biosensing are the focus of this review article.

Application of Antimicrobial Nanoparticles in Dentistry

Oral cavity incessantly encounters a plethora of microorganisms. Plaque biofilm-a major cause of caries, periodontitis and other dental diseases-is a complex community of bacteria or fungi that causes infection by protecting pathogenic microorganisms from external drug agents and escaping the host defense mechanisms. Antimicrobial nanoparticles are promising because of several advantages such as ultra-small sizes, large surface-area-to-mass ratio and special physical and chemical properties. To better summarize explorations of antimicrobial nanoparticles and provide directions for future studies, we present the following critical review. The keywords "nanoparticle," "anti-infective or antibacterial or antimicrobial" and "dentistry" were retrieved from Pubmed, Scopus, Embase and Web of Science databases in the last five years. A total of 172 articles met the requirements were included and discussed in this review. The results show that superior antibacterial properties of nanoparticle biomaterials bring broad prospects in the oral field. This review presents the development, applications and underneath mechanisms of antibacterial nanoparticles in dentistry including restorative dentistry, endodontics, implantology, orthodontics, dental prostheses and periodontal field.

From Nano to Micro: using nanotechnology to combat microorganisms and their multidrug resistance

The spread of antibiotic resistance and increasing prevalence of biofilm-associated infections is driving demand for new means to treat bacterial infection. Nanotechnology provides an innovative platform for addressing this challenge, with potential to manage even infections involving multidrug-resistant (MDR) bacteria. The current review summarizes recent progress over the last 2 years in the field of antibacterial nanodrugs, and describes their unique properties, mode of action and activity against MDR bacteria and biofilms. Biocompatibility and commercialization are also discussed. As opposed to the more common division of nanoparticles (NPs) into organic- and inorganic-based materials, this review classifies NPs into two functional categories. The first includes NPs exhibiting intrinsic antibacterial properties and the second is devoted to NPs serving as a cargo for delivering antibacterial agents. Antibacterial nanomaterials used to decorate medical devices and implants are reviewed here as well.

Versatile graphene-based photothermal nanocomposites for effectively capturing and killing bacteria, and for destroying bacterial biofilms

Bacterial infection is a worldwide health problem. Finding new potential antibacterial materials and developing advanced treatment strategies are becoming increasingly important and urgent. Herein, a versatile graphene-based photothermal nanocomposite was prepared for rapidly capturing and effectively eliminating both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli), and for destroying bacterial biofilms with near-infrared (NIR) irradiation. In this work, chitosan-functionalized magnetic graphene oxide (GO-IO-CS) was synthesized as a multifunctional therapy agent through a hydrothermal method. Chitosan could efficiently contact and capture bacteria by its positively charged surface functional groups, and graphene oxide could act as an effective photothermal killer to convert NIR light into local heat to enhance antibacterial activity. The super-paramagnetic properties of GO-IO-CS made it easy to separate and aggregate the bacteria, so improving the photothermal sterilization efficiency. GO-IO-CS was demonstrated to eliminate bacteria effectively after 10 min of NIR irradiation and to destroy bacterial biofilms. Furthermore, this antibiotic agent could be regenerated with an external magnet and reused in a subsequent antibacterial application.

Antimicrobial graphene family materials: Progress, advances, hopes and fears

Graphene-based materials have become very popular bionanotechnological instruments in the last few years. Since 2010, the graphene family materials have been recognized as worthy of attention due to its antimicrobial properties. Functionalization of graphene (or rather graphene oxide) surface creates the possibilities to obtain efficient antimicrobial agents. In this review, progress and advances in this field in the last few years are described and discussed. Special attention is devoted to materials based on graphene oxide in which specifically selected components significantly modify biological activity of this carbon structure. Short introduction concerns the physicochemical properties of the graphene family materials. In the section on antimicrobial properties, proposed mechanisms of activity against microorganisms are given showing enhanced action of nanocomposites also under light irradiation (photoinduced activity). Another important feature, i.e. toxicity against eukaryotic cells, is presented with up-to-date data. Taking into account all the information on the properties of the described materials and usefulness of the graphene family as antimicrobial agents, hopes and fears concerning their application are discussed. Finally, some examples of promising usage in medicine and other fields, e.g. in phytobiology and water remediation, are shown.