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Naringin, a natural product, can be used as a therapeutic agent due to its low systemic toxicity and negligible adverse effect. However, due to its hydrophobic nature and thereby low solubility, high-dose treatment is required when used for human therapy. Herein, we demonstrate the employment of a metal-organic framework (MOF) as a nontoxic loading carrier to encapsulate naringin, and the afforded nairngin@MOF composite can serve as a multifunctional bioplatform capable of treating Gram-positive bacteria and certain cancers by slowly and progressively releasing the encapsulated naringin as well as improving and modulating immune system functions through synergy between naringin and the MOF.

A novel complex comprising an ion pair of arginine–arginine carbamate is reported herein, which is isolated from an aqueous l-arginine solution after reacting with CO2. Its structure was unambiguou...

The synthesis, crystal structure, and antimicrobial efficacy are reported for a novel material comprising a 1:2 ratio of chlorhexidine (CHX) to N-cyclohexylsulfamate (i.e., artificial sweetener known as cyclamate). The chemical structure is unambiguously identified by incorporating a combination of single-crystal X-ray diffraction (SC-XRD), electrospray ionization mass spectrometry (ESI-MS), (1)H nuclear magnetic resonance (NMR) spectroscopy, correlation spectroscopy (COSY), and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). The new material: 1) is amongst only several reported structures identified to date incorporating the vital chlorhexidine antimicrobial drug; 2) exhibits broad spectrum antimicrobial activity at concentrations less than 15 μg/mL; and 3) provides a unique delivery method for the essential active pharmaceutical ingredient (API). Furthermore, substitution of inactive gluconate with bioactive cyclamate counterion potentially provides the additional benefit of improving the taste profile of chlorhexidine.

Cetylpyridinium tetrachlorozincate (referred to herein as (CP)2ZnCl4) was synthesized and its solid-state structure was elucidated via single-crystal X-ray diffraction (SC-XRD), revealing a stoichiometry of C42H76Cl4N2Zn with two cetylpyridinium (CP) cations per [ZnCl4]2– tetrahedra. Crystal structures at 100 and 298 K exhibited a zig-zag pattern with alternating alkyl chains and zinc units. The material showed potential for application as a broad-spectrum antimicrobial agent, to reduce volatile sulfur compounds (VSCs) generated by bacteria, and in the fabrication of advanced functional materials. Minimum inhibitory concentration (MIC) of (CP)2ZnCl4 was 60, 6, and 6 μg mL–1 for Salmonella enterica, Staphylococcus aureus, and Streptococcus mutans, respectively. The MIC values of (CP)2ZnCl4 were comparable to that of pure cetylpyridinium chloride (CPC), despite the fact that approximately 16% of the bactericidal CPC is replaced with bacteriostatic ZnCl2 in the structure. A modified layer-by-layer deposition technique was implemented to synthesize mesoporous silica (i.e., SBA-15) loaded with approximately 9.0 wt % CPC and 8.9 wt % Zn.

We present a way of stabilizing cationic partially hydrolyzed aluminum clusters in a non-acidic environment, through Ca2+ and L-Arginine doping. The Keggin Al13-mer (e-AlO4Al12(OH)24(H2O)127+) aluminum cluster can be stabilized with CaCl2 and L-arginine in a way to preserve the metal clusters. We use size-exclusion chromatography (SEC) and 27Al nuclear magnetic resonance (NMR) spectroscopy to demonstrate that positively-charged Keggin structures are preserved and that the conversion to Al(OH)3 materials is halted even at alkaline pH. The system serves to stabilize acidic Al clusters in alkaline or neutral conditions, while preserving their inherent cationic behavior.

Novel mesostructured silica microparticles are synthesized, characterized, and investigated as a drug delivery system (DDS) for antimicrobial applications. The materials exhibit a relatively high density (0.56 g per 1 g SiO2) of benzalkonium chloride (BAC), pore channels of 18 A in width, and a high surface area (1500 m2/g). Comparison of the small-angle X-ray diffraction (SAXRD) pattern with Barrett-Joyner-Halenda (BJH) pore size distribution data suggests that the 18 A pores exhibit short-range ordering and a wall thickness of ca. 12 A. Drug release studies demonstrate pH-responsive controlled release of BAC without additional surface modification of the materials. Prolonged drug release data were analyzed using a power law (Korsmeyer-Peppas) model and indicate substantial differences in release mechanism in acidic (pH 4.0, 5.0, 6.5) versus neutral (pH 7.4) solutions. Microbiological assays demonstrate a significant time-dependent reduction in Staphylococcus aureus and Salmonella enterica viability above 10 and 130 mg L-1 of the synthesized materials, respectively. The viability of cells is reduced over time compared to control samples. The findings will help in widening the use of BAC as a disinfectant and bactericidal agent, especially in pharmaceutical and food industries where Gram-positive and Gram-negative bacterial contamination is common.

In this paper, we report a simple template-free synthetic method that produces amorphous, nanoporous aluminosilicate and highly selective catalyst for toluene alkylation. The structure and composition of the material and its corresponding control material are characterized by various techniques. The material shows excellent catalytic selectivity for alkylation of toluene by tert-butyl alcohol in temperatures between 50–150 °C under atmospheric pressure, producing exclusively 4-tert-butlytoluene (ca. 99%).

We report a novel, facile, physical mixing synthetic method that leads to titanium silicate and copper titanium silicate materials or highly effective solid acid catalysts for toluene oxidation reaction. The synthesis involves simple physical mixing of tetraethyl orthosilicate and various titanium alkoxide (and also copper(II) chloride), and then calcination of the products. The effects of the types of precursors on the catalytic activity of the resulting materials are investigated. Notably, titanium(IV) n-butoxide, whose hydrolysis rate is close to that of tetraethyl orthosilicate, yields a material that exhibits strong acidic properties and excellent catalytic activity for toluene oxidation with hydrogen peroxide (H2O2) as oxidant, giving 98% conversion of toluene and ca. 100% selectivity to benzaldehyde product. The work demonstrates not only simplicity in terms of synthesis of the materials but also unprecedented solid-acid catalytic activity for titanium silicate materials, the catalytic properties of which can be easily tailored by varying the types of precursors. It is also noteworthy that the materials give among the best catalytic performance (in terms of both conversion and product selectivity) under mild reaction conditions that has been reported for toluene oxidation with H2O2 as oxidant for heterogeneous catalysts.

We present a way of stabilizing cationic partially hydrolyzed aluminum clusters in a non-acidic environment, through Ca2+ and l-Arginine doping. The Keggin Al13-mer (ε-AlO4Al12(OH)24(H2O)127+) aluminum cluster can be stabilized with CaCl2 and l-arginine in a way to preserve the metal clusters. We use size-exclusion chromatography (SEC) and 27Al nuclear magnetic resonance (NMR) spectroscopy to demonstrate that positively-charged Keggin structures are preserved and that the conversion to Al(OH)3 materials is halted even at alkaline pH. The system serves to stabilize acidic Al clusters in alkaline or neutral conditions, while preserving their inherent cationic behavior.

An ultrafine aluminum hydroxide nanoparticle suspension was prepared via the controlled titration of [Al(H2O)6]3+ with l-arginine to pH 4.6. The prepared material, predominantly 10–30 nm in diameter, was purified by GPC and subsequently identified as the gibbsite (or hydrargillite) polymorph via FTIR, powder XRD, and elemental analysis. The material’s chemical environment and morphology were probed using 27Al/1H NMR, FTIR, ICP-OES, TEM-EDS, XPS, XRD, and N2 adsorption experiments. Furthermore, by incorporating the newly developed synthetic route, Al(OH)3 was partially loaded inside the mesopores (2.7 nm) of MCM-41. EDS and NMR analysis indicated that both tetrahedral and octahedral Al (Oh/Td = 1.4) are incorporated at 11% w/w total Al and that the Si/Al ratio is 2.9, indicating that part of the Al is embedded in the Si framework. In addition, differences in elemental composition between surface XPS and bulk EDS analysis provided insight into the distribution of Al within the material. A higher Si/Al ratio...

An aqueous suspension of nanogibbsite was synthesized via the titration of aluminum aqua acid [Al(H(2)O)(6)](3+) with L-arginine to pH 4.6. Since the hydrolysis of aqueous aluminum salts is known to produce a wide array of products with a wide range of size distributions, a variety of state-of-the-art instruments (i.e., (27)Al/(1)H NMR, FTIR, ICP-OES, TEM-EDX, XPS, XRD, and BET) were used to characterize the synthesis products and identification of byproducts. The product, which was comprised of nanoparticles (10-30 nm), was isolated using gel permeation chromatography (GPC) column technique. Fourier transform infrared (FTIR) spectroscopy and powder X-ray diffraction (PXRD) identified the purified material as the gibbsite polymorph of aluminum hydroxide. The addition of inorganic salts (e.g., NaCl) induced electrostatic destabilization of the suspension, thereby agglomerating the nanoparticles to yield Al(OH)(3) precipitate with large particle sizes. By utilizing the novel synthetic method described here, Al(OH)(3) was partially loaded inside the highly ordered mesoporous framework of MCM-41, with average pore dimensions of 2.7 nm, producing an aluminosilicate material with both octahedral and tetrahedral Al (O(h)/T(d) = 1.4). The total Al content, measured using energy-dispersive X-ray spectrometry (EDX), was 11% w/w with a Si/Al molar ratio of 2.9. A comparison of bulk EDX with surface X-ray photoelectron spectroscopy (XPS) elemental analysis provided insight into the distribution of Al within the aluminosilicate material. Furthermore, a higher ratio of Si/Al was observed on the external surface (3.6) as compared to the bulk (2.9). Approximations of O/Al ratios suggest a higher concentration of Al(O)(3) and Al(O)(4) groups near the core and external surface, respectively. The newly developed synthesis of Al-MCM-41 yields a relatively high Al content while maintaining the integrity of the ordered silica framework and can be used for applications where hydrated or anhydrous Al(2)O(3) nanoparticles are advantageous.

Since their discovery in the early 1990s, mesoporous silica materials have captured the attention of researchers worldwide because of their unique properties as well as their potential applications in catalysis, drug delivery, chromatography, separations, environmental remediation, and nanoelectronics. Their properties and applications are largely dependent on their nanoporous structures and high surface areas, which allow the materials to support or carry various functional groups (e.g., drug molecules). Furthermore, their properties can easily be tailored, as needed, by a simple modification of their surfaces with various functional groups. In this chapter, a brief historical background on mesoporous materials and the major synthetic methods used to make various mesoporous materials with different structures are discussed. Several notable mesoporous materials and their fundamental properties and potential applications in areas including catalysis, drug delivery, nanomedicine, and nanoelectronics are also included. Some of the unique advantages of these materials for various applications are highlighted by presenting some examples, such as stimuli-responsive, and on demand delivery of anticancer drugs to targeted cells. Finally, conclusions and the authors’ perspectives on where the field of mesoporous materials currently stands and what more may have to be done to fully utilize these materials in various commercial products are discussed.

This review article provides an overview of hybrid and nanocomposite materials used as biomaterials in nanomedicine, focusing on applications in controlled drug delivery, tissue engineering, biosensors and theranostic systems. Special emphasis is placed on the importance of tuning the properties of nanocomposites, which can be achieved by choosing appropriate synthetic methods and seeking synergy among different types of materials, particularly exploiting their nanoscale nature. The challenges in fabrication for the nanocomposites are highlighted by classifying them as those comprising solely inorganic phases (inorganic/inorganic hybrids), organic phases (organic/organic hybrids) and both types of phases (organic/inorganic hybrids). A variety of examples are given for applications from the recent literature, from which one may infer that significant developments for effective use of hybrid materials require a delicate balance among structure, biocompatibility, and stability.