Sustained release from a metal - Analgesics entrapped within biocidal silver

Metal nanoparticles entrapped in metal matrices

We developed synthetic methods for the doping of metals (M) with metallic nanoparticles (NPs). To the best of our knowledge - unlike oxides, polymers and carbon-based supports - metals were not used so far as supporting matrices for metallic NPs. The composites (denoted M1-NPs@M2) comprise two separate phases: the metallic NPs (the dopant) and the entrapping 3D porous metallic matrix, within which the NPs are intimately held and well dispersed. Two different general synthetic strategies were developed, each resulting in a group of materials with characteristic structure and properties. The first strategy uses pre-prepared NPs and these are entrapped during reductive formation of the metallic matrix from its cation. The second strategy is in situ growth of the doped metallic NPs within the pre-prepared entrapping metallic matrix. These two methods were developed for two types of entrapping metallic matrices with different morphologies: porous aggregated metallic matrices and metallic foams. The leading case in this study was the use of Pt as the NP dopant and Ag as the entrapping matrix, using all of the four combinations - entrapment or growth within aggregated Ag or Ag foam matrices. Full physical and chemical properties analysis of these novel types of materials was carried out, using a wide variety of analytical methods. The generality of the methods developed for these bi-metallic composites was investigated and demonstrated on additional metallic pairs: Au NPs within Ag matrices, Pd NPs within Ni matrices and Ir-NPs within a Rh matrix. As the main application of metallic NPs is in catalysis, the catalytic activity of M1-NPs@M2 is demonstrated successfully for entrapped Pt within Ag for reductive catalytic reactions, and for Pd within Ni for the electrocatalytic hydrogen oxidation reaction.

Silver-Polymethylhydrosiloxane Nanocomposite Coating on Anodized Aluminum with Superhydrophobic and Antibacterial Properties

Biofilm formation on both animate and inanimate surfaces serves as an ideal bacterial reservoir for the spread of nosocomial infections. Designing surfaces with both superhydrophobic and antibacterial properties can help reduce initial bacterial attachment and subsequent biofilm formation. In the present study, a two-step approach is deployed to fabricate silver-polymethylhydrosiloxane (Ag-PMHS) nanocomposites, followed by a simple dip-coating deposition on anodized Al. Ag-nanoparticles (Ag-NPs) are synthesized in situ within a PMHS polymeric matrix. Morphological features of Ag-PMHS coating observed by scanning electron microscopy shows heterogeneous micro-nano-structures. The chemical compositions of these coatings were characterized using X-ray diffraction and attenuated total reflection-Fourier transform infrared spectroscopy, which indicate the presence of a low-energy PMHS polymer. The as-synthesized Ag-PMHS nanocomposite demonstrated excellent antibacterial properties against clinically relevant planktonic bacteria with zone of inhibition values of 25.3 ± 0.5, 24.8 ± 0.5, and 23.3 ± 3.6 mm for Pseudomonas aeruginosa (P.A) (Gram -ve), Escherichia coli (E. coli) (Gram -ve), and Staphylococcus aureus (S.A) (Gram +ve), respectively. The Ag-PMHS nanocomposite coating on anodized Al provides an anti-biofouling property with an adhesion reduction of 99.0, 99.5, and 99.3% for Pseudomomas aeruginosa (P.A), E. coli, and S. aureus (S.A), respectively. Interestingly, the coating maintained a stable contact angle of 158° after 90 days of immersion in saline water (3.5 wt % NaCl, pH 7.4). The Ag-PMHS nanocomposite coating on anodized Al described herein demonstrates excellent antibacterial and anti-biofouling properties owing to its inherent superhydrophobic property.

Encoding Chiral Molecular Information in Metal Structures

The concept of encoding molecular information in bulk metals has been proposed over the past decade. The structure of various types of molecules, including enantiomers, can be imprinted in achiral substrates. Typically, to encode metals with chiral information, several approaches, based on chemical and electrochemical concepts, can be used. In this Minireview, recent achievements with respect to the development of such materials are discussed, including the entrapment of chiral biomolecules in metals, the chiral imprinting of metals, as well as the combination of imprinting with nanostructuring. The features and potential applications of these designer materials, such as chirooptical properties, enantioselective adsorption and separation, as well as their use for asymmetric synthesis will be presented. This will illustrate that the development of molecularly encoded metal structures opens up very interesting perspectives, especially in the frame of chiral technologies.

Random peptide mixtures entrapped within a copper-cuprite matrix: new antimicrobial agent against methicillin-resistant Staphylococcus aureus

The emergence of global antibiotic resistance necessitates the urgent need to develop new and effective antimicrobial agents. Combination of two antimicrobial agents can potentially improve antimicrobial potency and mitigate the development of resistance. Therefore, we have utilized metal molecular doping methodology whereby antimicrobial random peptides mixture (RPMs) are entrapped in a bactericidal copper metal matrix. The copper/RPM composite exhibits greater antimicrobial activity toward methicillin-resistant Staphylococcus aureus (MRSA) than either copper or RPMs alone. Our findings indicate that this bactericidal antimicrobial biomaterial could be utilized to efficiently eradicate antibiotic-resistant pathogenic bacteria for health, agricultural and environmental applications.

In silico validation of the non-antibiotic drugs acetaminophen and ibuprofen as antibacterial agents against red complex pathogens

BACKGROUND

Acetaminophen (APAP) and ibuprofen (IB) are drugs commonly used to alleviate pain due to their anti-inflammatory, anti-pyretic, and analgesic effect. The aim of the present study is to unravel the molecular mechanisms underlying the antimicrobial potential of these two drugs against red complex pathogens, namely, Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia, by using in silico tools, since they are potentially associated with inflammatory conditions related to periodontal infections.

METHODS

The STITCH v5.0 pipeline was primarily used for identifying drug-protein interactions; VirulentPred and VICMPred were used for elucidating the virulence property and functional class of the proteins. The subcellular localization of virulent proteins was assessed using PSORTb v3.0 and the epitopes were identified using BepiPred v1.0 Linear Epitope Prediction tool.

RESULTS

APAP and IB were found to interact with proteins involved in cellular process, metabolism, and virulence. The virulent proteins targeted by the drugs were located in the cytoplasm, which would further add to the effectiveness of the drugs to serve as antimicrobial agents. Finally, epitope prediction revealed multiple epitopes in the virulent proteins which can be specifically focused on.

CONCLUSIONS

APAP and IB were found to target vital proteins involved in the cellular process, metabolism, and virulence of red complex pathogens. An in-depth knowledge on the interaction of these drugs and their antibacterial activity would add to the plethora of merits gained by these drugs in clinical settings. Further in vitro studies on a wide range of pathogens are warranted to substantiate the true interactions between the drugs and the protein repertoire of pathogens.

Entrapment of Drugs within Metallic Platinum and Their Delivery

Platinum has been a widely used metal for a variety of implanted medical devices, because of its inertness, low corrosion rate, high biocompatibility, high electric conductivity, and good mechanical stability. A highly desirable property still in need to be addressed is the tailoring of drug-delivery ability to that metal. This is needed in order to treat infections due to the process of implanting, to treat postoperation pain, and to prevent blood clotting. Can Pt itself serve as a delivery matrix? A review on metallic implants (Lyndon, J. A.; Boyd, B. J.; Birbilis, N. Metallic implant drug/device combinations for controlled drug release in orthopaedic applications. J. Control. Release 2014, 179, 63-75) proposes that "Metals themselves can be used for delivering pharmaceutics" but adds that "there has been no current research into [that] possibility" despite its advantages. Here we present a solution to that challenge and show a new method of using an inert metal as a 3D matrix from within which entrapped drug molecules are released. This new type of drug-delivery system is fabricated by the methodolodgy of entrapment of molecules within metals, resulting in various drugs@Pt. Specifically the following drugs have been entrapped and released: the pain-killer and platelet-inhibitor nonsteroidal anti-inflammatory drugs (NSAIDs) ibuprofen and naproxen, the antibiotic ciprofloxacin, and the antiseptic chlorhexidine. The delivery profiles of all biocomposites were studied in two forms, powders and pressed discs, showing, in general, fast followed by slow first order release profiles. It is shown that the delivery kinetics can be tailored by changing the entrapment process, by applying different pressures in the disc preparation, and by changing the delivery temperature. The latter was also used to determine the activation energy for the release. Full characterization of the metallic biomaterials is provided, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDAX), thermogravimetric analysis (TGA), and surface area/porosity analysis.

Fine-tuning of the metal work function by molecular doping

Fine tuning of the metal work function (WF) in the range of 1 eV by 3D molecular doping of metals.