The present study is focused on the synthesis and characterization of nitric oxide (NO)-releasing superparamagnetic iron oxide nanoparticles (Fe₃O₄ NPs), and their incorporation in Pluronic F127 hydrogel with great potential for topical applications. Magnetite nanoparticles (Fe₃O₄ NPs) were synthesized by thermal decomposition of acetylacetonate iron (Fe(acac)₃), and coated with the thiol containing molecule mercaptosuccinic acid (MSA), leading to Fe₃O₄-MSA NPs. The obtained NPs were characterized using different techniques. The results showed that the Fe₃O₄-MSA NPs have a mean diameter of 11 nm, in the solid state, and superparamagnetic behavior at room temperature. Fe₃O₄-MSA NPs have an average hydrodynamic size of (78.0 ± 0.9) nm, average size distribution (PDI) of 0.302 ± 0.04, and zeta potential of (−22.10 ± 0.55) mV. Free thiol groups on the Fe₃O₄-MSA NP surface were nitrosated by the addition of sodium nitrite, yielding S-nitrosated magnetic nanoparticles (Fe₃O₄-S-nitroso-MSA NPs), which act as spontaneous NO donors upon S–N bond cleavage. The amount of (86.4 ± 4.7) μmol of NO was released per gram of Fe₃O₄-S-nitroso-MSA NPs. In order to enhance NP dispersion, Fe₃O₄-MSA NPs were incorporated in Pluronic F127 hydrogel (3.4% w/w), and characterized using different techniques. Rheological measurements suggest a potential use for Fe₃O₄-MSA NPs dispersed in Pluronic hydrogel for topical applications. Atomic force microscopy (AFM) showed that the NPs are embedded within the Pluronic film while the X-ray photoelectron spectroscopy (XPS) spectrum of the Fe₃O₄-MSA NPs samples revealed the presence of iron, oxygen, carbon and sulfur, confirming the presence of MSA molecules on the NP surface.

Introduction: One of the most common strategies for pain control during and after surgical procedures is the use of local anesthetics. Prolonged analgesia can be safely achieved with drug delivery systems suitably chosen for each local anesthetic agent. Areas covered: This review considers drug delivery formulations of local anesthetics designed to prolong the anesthetic effect and decrease toxicity. The topics comprise the main drug delivery carrier systems (liposomes, biopolymers, and cyclodextrins) for infiltrative administration of local anesthetics. A chronological review of the literature is presented, including details of formulations as well as the advantages and pitfalls of each carrier system. The review also highlights pharmacokinetic data on such formulations, and gives an overview of the clinical studies published so far concerning pain control in medicine and dentistry. Expert opinion: The design of novel drug delivery systems for local anesthetics must focus on how to achieve higher uploads of the anesthetic into the carrier, and how to sustain its release. This comprehensive review should be useful to provide the reader with the current state-of-art regarding drug delivery formulations for local anesthetics and their possible clinical applications.

Introduction: Topical anesthesia is widely used in dentistry to reduce pain caused by needle insertion and injection of the anesthetic. However, successful anesthesia is not always achieved using the formulations that are currently commercially available. As a result, local anesthesia is still one of the procedures that is most feared by dental patients. Drug delivery systems (DDSs) provide ways of improving the efficacy of topical agents. Areas covered: An overview of the structure and permeability of oral mucosa is given, followed by a review of DDSs designed for dental topical anesthesia and their related clinical trials. Chemical approaches to enhance permeation and anesthesia efficacy, or to promote superficial anesthesia, include nanostructured carriers (liposomes, cyclodextrins, polymeric nanoparticle systems, solid lipid nanoparticles, and nanostructured lipid carriers) and different pharmaceutical dosage forms (patches, bio- and mucoadhesive systems, and hydrogels). Physical methods include pre-cooling, vibration, iontophoresis, and microneedle arrays. Expert opinion: The combination of different chemical and physical methods is an attractive option for effective topical anesthesia in oral mucosa. This comprehensive review should provide the readers with the most relevant options currently available to assist pain-free dental anesthesia. The findings should be considered for future clinical trials.