Mesoporous silica nanoparticles (MSNs) are very promising nanomaterials for treating bacterial infections when combined with pharmaceutical drugs. Herein, we report the preparation of two nanomaterials based on the immobilization of ciprofloxacin in mesoporous silica nanoparticles, either as the counter-ion of the choline derivative cation (MSN-[Ch][Cip]) or via anchoring on the surface of amino-group modified MSNs via an amide bond (MSN-Cip). Both nanomaterials were characterized by TEM, FTIR and solution ¹H NMR spectroscopies, elemental analysis, XRD and N₂ adsorption at 77 K in order to provide the desired structures. No cytotoxicity from the prepared mesoporous nanoparticles on 3T3 murine fibroblasts was observed. The antimicrobial activity of the nanomaterials was determined against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Klebsiella pneumoniae) bacteria and the results were promising against S. aureus. In the case of B. subtilis, both nanomaterials exhibited higher antimicrobial activity than the precursor [Ch][Cip], and in the case of K. pneumoniae they exhibited higher activity than neutral ciprofloxacin.

Antiseptics and disinfectants are extensively used for a variety of topical and hard-surface applications. A wide variety of biocides as active chemical agents is found in these products, including alcohols, phenols, iodine, and chlorine. Many of these active agents demonstrate broad-spectrum antimicrobial activity; however, the mode of action of these agents is not well-documented. This review is focused on several examples of ionic systems based on ionic surfactants and ionic liquids as well as nanomaterials and nanoparticles acting as antiseptics and disinfectants for surfaces. It is important to note that many of these biocides may be used singly or in combination in a variety of products, which vary considerably in activity against microorganisms. Antimicrobial activity can be influenced by several factors such as formulation effects, presence of an organic load, synergy, temperature, dilution, and test method. The most promissory compounds based on ionic systems and nanomaterials published in mainly the last decade is chronologically reported in this review.

The combination of active pharmaceutical ingredients in the form of ionic liquids or organic salts (API-OSILs) with mesoporous silica nanoparticles (MSNs) as drug carriers can provide a useful tool in enhancing the capabilities of current antibiotics, especially against resistant strains of bacteria. In this publication, the preparation of a set of three nanomaterials based on the modification of a MSN surface with cholinium ([MSN-Chol][Cip]), 1-methylimidazolium ([MSN-1-MiM][Cip]) and 3-picolinium ([MSN-3-Pic][Cip]) ionic liquids coupled with anionic ciprofloxacin have been reported. All ionic liquids and functionalized nanomaterials were prepared through sustainable protocols, using microwave-assisted heating as an alternative to conventional methods. All materials were characterized through FTIR, solution ¹H NMR, elemental analysis, XRD and N₂ adsorption at 77 K. The prepared materials showed no in vitro cytotoxicity in fibroblasts viability assays. The minimum inhibitory concentration (MIC) for all materials was tested against Gram-negative K. pneumoniae and Gram-positive Enterococcus spp., both with resistant and sensitive strains. All sets of nanomaterials containing the anionic antibiotic outperformed free ciprofloxacin against resistant and sensitive forms of K. pneumoniae, with the prominent case of [MSN-Chol][Cip] suggesting a tenfold decrease in the MIC against sensitive strains. Against resistant K. pneumoniae, a five-fold decrease in the MIC was observed for all sets of nanomaterials compared with neutral ciprofloxacin. Against Enterococcus spp., only [MSN-1-MiM][Cip] was able to demonstrate a slight improvement over the free antibiotic.

Phenylpropanoic sugar esters are a class of naturally occurring active substances, mainly found in ancient oriental medicinal plants (Figure 1), with a scope of activity ranging from antioxidant, antibacterial as well as anti-tumoral [ 1 Panda P , Appalashetti M , Judeh ZMA , et al. Phenylpropanoid sucrose esters: plant-derived natural products as potential leads for new therapeutics. CMC. 2011;18(21):3234–3251. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] ]. Though relatively simple in structure – owing to their resemblance to natural carbohydrates - few have been the successful attempts to obtain them in the laboratory, hampered mainly by the fact that the high similarity between functional groups in sugars restrains the feasibility of current methods and their reproducibility in industrial scales [ 2 Barros MT , Petrova KT , Correia-da-Silva P , et al. Library of mild and economic protocols for the selective derivatization of sucrose under microwave irradiation. Green Chem. 2011;13(7):1897–1906. [Crossref], [Web of Science ®] , [Google Scholar] ]. Our study aims for the development of reliable and effective methods for the synthesis of a library of phenylpropanoic esters derived from sucrose. The lead-compounds are obtained by treating sucrose with a vigorous basic medium. The preferential esterification in the sugar hydroxyls is catalysed by a metal halide salt. The different compounds obtained are meant to be tested and screened for their biological applications, with particular emphasis on their action against cancer cells. Our most appealing discovery is the possibility of directly enhancing the regioselectivity of the 2, 3′, 6 and 6′-hydroxyl positions in the sugar moiety induced by transition-metal salts as catalysts [ 3 Avela,S , Aspelund B , Holmbom B , Melander B , Jalonen H , Peltonen C. et al. Selective Substitution of Sucrose Hydroxyl Groups via Chelates In Sucrochemistry; Hickson, J.; ACS Symposium Series; American Chemical Society: Washington, DC 1977;41:62–79. [Crossref] , [Google Scholar] ] (Scheme 1). Different metal salts induce the different hydroxyls mentioned for a direct esterification with the acylating agent, which reflects the specificity and versatility of this novel class of reactions. We can conclude, so far, that cobalt and copper chloride salts give the best results in terms of yield (more than 30% conversion) and decreased reaction time (less than one hour). To further extend our knowledge about the metal-chelate directed acylation method, we are also experimenting with other halide salts, namely zinc, calcium, nickel and iron, as well as with derivatized molecules of sucrose. Thus, our work can certainly lead the development of novel drugs and resourceful cancer therapies.