Functionalized nanosponges for controlled antibacterial and antihypocalcemic actions

Dextrin-Based Nanohydrogels for Rokitamycin Prolonged Topical Delivery

Macrolides are widely used antibiotics with a broad spectrum of activity. The development of drug carriers to deliver this type of antibiotics has attracted much research. The present study aims at developing new swellable dextrin-based nanohydrogels for the topical delivery of rokitamycin, as model macrolide. Rokitamycin is a synthetic analogous of macrolides with advantageous characteristics as far as bacterial uptake and post-antibiotic effect are concerned. It is also indicated for the treatment of severe infections caused by Acanthamoeba and for topical infections. The nanohydrogels have been prepared from two types of cross-linked polymers obtained by using β-cyclodextrin or Linecaps^® was provided by the Roquette Italia SPA (Cassano Spinola, Al, Italy) as building blocks. The cross-linked polymers have been then formulated into aqueous nanosuspensions refined and tuned to achieve the incorporation of the drug. Cross-linked β-cyclodextrin (β-CD) and Linecaps^® (LC) polymers formed dextrin-based nanohydrogels with high swelling degree and mucoadhesion capability. Rokitamycin was loaded into the nanohydrogels displaying an average size around 200 nm with negative surface charge. In vitro kinetic profiles of free and loaded drug in nanohydrogels were compared at two pH levels. Interestingly, a sustained and controlled release was obtained at skin pH level due to the high degree of swelling and a pH responsiveness possibly. The results collected suggest that these nanohydrogels are promising for the delivery of rokitamycin and may pave the way for the topical delivery of other macrolide antibiotics.

Microsponge based gel as a simple and valuable strategy for formulating and releasing Tazarotene in a controlled manner

This study aims to deliver Tazarotene (TZR) in a controlled manner to reduce adverse effects in the form of a microsponge-based gel. It adopts the methodology of a similar study by the undersigned authors with respect to the drug Clindamycin. Under both studies, the methodology used is emulsion solvent diffusion. Accordingly, we altered the concentrations of polymer and emulsifier to generate four formulations of TZR microsponges. Additionally, we used two types of emulsifiers and two types of solvents to develop two further microsponge formulations. We then studied the physical properties of each formulation, as well as drug-polymer interactions. Echoing findings from our prior study of Clindamycin, we found that microsponge formulations coded by T1 and T3 had superior production yield and entrapment efficiency, and their particle size was suitable for dermal application. As in the prior Clindamycin study, each of the T1 and T3 microsponge formulations were incorporated into a Carbopol gel and evaluated in vitro. The optimal formulation was found to be the microsponge formulation gel T8, which released 87.63% of TZR over 12 h. No significant interactions between the drug and excipients were found through Fourier transform infrared spectroscopy and differential scanning calorimetry.

A 3D Printed Bone Tissue Engineering Scaffold Composed of Alginate Dialdehyde-Gelatine Reinforced by Lysozyme Loaded Cerium Doped Mesoporous Silica-Calcia Nanoparticles

A novel biomaterial comprising alginate dialdehyde-gelatine (ADA-GEL) hydrogel augmented by lysozyme loaded mesoporous cerium doped silica-calcia nanoparticles (Lys-Ce-MSNs) was 3D printed to create bioactive scaffolds. Lys-Ce-MSNs raised the mechanical stiffness of the hydrogel composite scaffold and induced surface apatite mineralization, when the scaffold was immersed in simulated body fluid (SBF). Moreover, the scaffolds could co-deliver bone healing (Ca and Si) and antioxidant ions (Ce), and Lys to achieve antibacterial (and potentially anticancer) properties. The nanocomposite hydrogel scaffolds could hold and deliver Lys steadily. Based on the in vitro results, the hydrogel nanocomposite containing Lys assured improved pre-osteoblast cell (MC3T3-E1) proliferation, adhesion, and differentiation, thanks to the biocompatibility of ADA-GEL, bioactivity of Ce-MSNs, and the stabilizing effect of Lys on the scaffold structure. On the other hand, the proliferation level of MG63 osteosarcoma cells decreased, likely due to the anticancer effect of Lys. Last but not least, cooperatively, alongside gentamicin (GEN), Lys brought about a proper antibacterial efficiency to the hydrogel nanocomposite scaffold against gram-positive and gram-negative bacteria. Taken together, ADA-GEL/Lys-Ce-MSN nanocomposite holds great promise for 3D printing of multifunctional hydrogel BTE scaffolds, able to induce bone regeneration, address infection, and potentially inhibit tumor formation and growth. This article is protected by copyright. All rights reserved.

Nutraceutical Concepts and Dextrin-Based Delivery Systems

Nutraceuticals are bioactive or chemical compounds acclaimed for their valuable biological activities and health-promoting effects. The global community is faced with many health concerns such as cancers, cardiovascular and neurodegenerative diseases, diabetes, arthritis, osteoporosis, etc. The effect of nutraceuticals is similar to pharmaceuticals, even though the term nutraceutical has no regulatory definition. The usage of nutraceuticals, to prevent and treat the aforementioned diseases, is limited by several features such as poor water solubility, low bioavailability, low stability, low permeability, low efficacy, etc. These downsides can be overcome by the application of the field of nanotechnology manipulating the properties and structures of materials at the nanometer scale. In this review, the linear and cyclic dextrin, formed during the enzymatic degradation of starch, are highlighted as highly promising nanomaterials- based drug delivery systems. The modified cyclic dextrin, cyclodextrin (CD)-based nanosponges (NSs), are well-known delivery systems of several nutraceuticals such as quercetin, curcumin, resveratrol, thyme essential oil, melatonin, and appear as a more advanced drug delivery system than modified linear dextrin. CD-based NSs prolong and control the nutraceuticals release, and display higher biocompatibility, stability, and solubility of poorly water-soluble nutraceuticals than the CD-inclusion complexes, or uncomplexed nutraceuticals. In addition, the well-explored CD-based NSs pathways, as drug delivery systems, are described. Although important progress is made in drug delivery, all the findings will serve as a source for the use of CD-based nanosystems for nutraceutical delivery. To sum up, our review introduces the extensive literature about the nutraceutical concepts, synthesis, characterization, and applications of the CD-based nano delivery systems that will further contribute to the nutraceutical delivery with more potent nanosystems based on linear dextrins.

Cyclodextrin-Based Nanosponges: Overview and Opportunities

Nanosponges are solid cross-linked polymeric nano-sized porous structures. This broad concept involves, among others, metal organic frameworks and hydrogels. The focus of this manuscript is on cyclodextrin-based nanosponges. Cyclodextrins are cyclic oligomers of glucose derived from starch. The combined external hydrophilicity with the internal hydrophobic surface constitute a unique "microenvironment", that confers cyclodextrins the peculiar ability to form inclusion host‒guest complexes with many hydrophobic substances. These complexes may impart beneficial modifications of the properties of guest molecules such as solubility enhancement and stabilization of labile guests. These properties complemented with the possibility of using different crosslinkers and high polymeric surface, make these sponges highly suitable for a large range of applications. Despite that, in the last 2 decades, cyclodextrin-based nanosponges have been developed for pharmaceutical and biomedical applications, taking advantage of the nontoxicity of cyclodextrins towards humans. This paper provides a critical and timely compilation of the contributions involving cyclodextrins nanosponges for those areas, but also paves the way for other important applications, including water and soil remediation and catalysis.

Cyclodextrin-Based Nanosponges as Perse Antimicrobial Agents Increase the Activity of Natural Antimicrobial Peptide Nisin

At present, antibiotic resistance is considered a real problem. Therefore, for decades scientists have been looking for novel strategies to treat bacterial infections. Nisin Z, an antimicrobial peptide (AMP), can be considered an option, but its usage is mainly limited by the poor stability and short duration of its antimicrobial activity. In this context, cyclodextrin (CD)-based nanosponges (NSs), synthesized using carbonyldiimidazole (CDI) and pyromellitic dianhydride (PMDA), were chosen for nisin Z loading. To determine the minimum inhibitory of nisin Z loaded on CD-NS formulations, agar well diffusion plates were used. Then, the bactericide concentrations of nisin Z loaded on CD-NS formulations were determined against Gram-positive (Staphylococcus aureus) and -negative (Escherichia coli) bacteria, using microdilution brain heart infusion (BHI) and tetrazolium salt 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). The minimum and bactericide inhibitory values of the nisin complex with NSs were potentially decreased against both bacteria, compared with the nisin-free sample, while the nisin complex with β-CD showed lower antibacterial activity. The antimicrobial effect was also demonstrated by free NSs. Furthermore, the total viable counts (TVCs) antibacterial experiment indicated that the combination of nisin Z in both PMDA and CDI β-CD-based NSs, especially CDI, can provide a better conservative effect on cooked chicken meat. Generally, the present study outcomes suggest that the cross-linked β-CD-based NSs can present their own antimicrobial potency or serve as promising carriers to deliver and enhance the antibacterial action of nisin Z.

Optimization of entrapment efficiency and release of clindamycin in microsponge based gel

The aim of the present study was to formulate clindamycin (CLN) as a microsponge based gel to release the drug in a controlled manner and reduce the side effects in the treatment of acne. Since this method requires poor water solubility of the drug to be loaded in particles, therefore, conversion of the hydrochloride salt to free base was done. By using an emulsion solvent diffusion method, we made six different formulations of microsponges containing CLN-free base by changing the proportions of polymer, emulsifier and the pH of the external phase. These formulations were studied for physical characterization and for drug- polymer interactions. The physical characterization showed that microsponge formulations coded by C5, C6 resulted in a better loading efficiency and production yield and their particle size was less than 30 µm. Scanning electron microscopy images showed the microsponges porous and spherical. C5, C6 microsponge formulation was prepared as gel in Carbopol and in vitro evaluated. The microsponge formulation gel C8 was found to be optimized. C8 released 90.38% of drug over 12 h and showed viscosity 20,157 ± 38 cp, pH of 6.3 ± 0.09 and drug content of 99.64 ± 0.04%. Fourier transform infrared spectroscopy and differential scanning calorimetry confirmed no significant interactions between excipients and drug.

Formulation Development, In Vitro and In Vivo Evaluation of Topical Hydrogel Formulation of Econazole Nitrate-Loaded β-Cyclodextrin Nanosponges

Econazole nitrate, an antifungal drug used in the handling of skin ailments, is commercially not efficient as these ailments typically require a more elevated concentration of the drug to offer an effective pharmacological retort. Like so, it is proposed to assess the effectiveness of the topical hydrogel of econazole-loaded nanosponge in the management of skin ailment(s). Econazole nitrate-laden β-cyclodextrin nanosponges were developed by employing the melt method using β-cyclodextrin as the organic polymer and N,N-carbonyldiimidazole as the crosslinker. The critical factors disturbing the quality of the formulation were uniquely identified by the Ishikawa diagram, and they were optimized by the statistical experiment design concept. β-cyclodextrin loaded nanosponges were uniquely designed using the Placket-Burman approach and optimized utilizing the Box-Behnken method. The optimized nanosponges (EN-CDN) were  421.37 ± 6.19 nm in size with an entrapment efficiency of 70.13% ± 5.73%. The topical hydrogel of nanosponges (EN-TG) was prepared using carbopol 934 and pyrrolidone as permeation enhancers. In vitro skin permeation studies affirmed the improved transport crosswise the goatskin for topical hydrogel in comparison to the marketed product. EN-TG was able to control the fungal infection in the selected animal model in comparison to the marketed preparation. Stability studies reported favorably that nanogel remained stable under normal and accelerated settings.

Cyclodextrin Monomers and Polymers for Drug Activity Enhancement

Cyclodextrins (CDs) and cyclodextrin (CD)-based polymers are well-known complexing agents. One of their distinctive features is to increase the quantity of a drug in a solution or improve its delivery. However, in certain instances, the activity of the solutions is increased not only due to the increase of the drug dose but also due to the drug complexation. Based on numerous studies reviewed, the drug appeared more active in a complex form. This review aims to summarize the performance of CDs and CD-based polymers as activity enhancers. Accordingly, the review is divided into two parts, i.e., the effect of CDs as active drugs and as enhancers in antimicrobials, antivirals, cardiovascular diseases, cancer, neuroprotective agents, and antioxidants.

Drug-Encapsulated Cyclodextrin Nanosponges

To date, a number of nanocarriers, either inorganic or organic, have been developed to improve the delivery and therapeutic efficacy of various drugs. Drug delivery systems have attempted to overcome the undesirable pharmacokinetic problems encountered. Among the various nanomaterials that have been designed as potential nanocarriers, cyclodextrin-based polymers are of particular interest in this review.Cyclodextrins (CD) are a class of cyclic glucopyranose oligomers, obtained from starch by enzymatic action, with a characteristic toroidal shape that forms a truncated cone-shaped lipophilic cavity. The main common native cyclodextrins are named α, β, and γ which comprise six, seven, and eight glucopyranose units, respectively. Cyclodextrins have the capability to include compounds whose size and polarity are compatible with those of their cavity.Cyclodextrin-based cross-linked polymers, often referred to as "cyclodextrin nanosponges" (CDNSs), attract great attention from researchers for solving major bioavailability problems such as inadequate solubility, poor dissolution rate, and limited stability of some agents, as well as increasing their effectiveness and decreasing unwanted side effects.Registered patents about this novel system in various fields, different pharmaceutical applications, and classes of drugs encapsulated by CDNSs are detailed. The features outlined make CDNSs a promising platform for the development of innovative and advanced delivery systems.

Nanosponges as protein delivery systems: Insulin, a case study

Cyclodextrin-based nanosponges have been found to bepromising drug delivery systems. This paper investigates an application that still needs to be studied in depth, that is, the oral delivery of peptides and proteins, choosing insulin as a case study. The nanospongewas synthesized by crosslinkingβ-cyclodextrins withpyromellitic dianhydride, adopting a top-down approach for its subsequent formulation. Aphysicochemical characterization, in-vitro andin-vivo tests were carried out on the formulation developed. It was nanometric (around 250 nm) with high negative zeta potential, mucoadhesion and swelling properties, good loading capability (about 14%) and encapsulation efficiency (above 90%). The in-vitro release of insulin was negligible at a gastric pH (below 2%) while sustained at an intestinal pH, thus showing a pH-sensitive behaviour of the nanosponge. The Caco-2 cell permeability assay proved that the intestinal permeation of insulin was enhanced when loaded inside the nanosponge. The in-vivo studies confirmed the presence of insulin in rat plasma and a marked hypoglycemic effect in diabetic mice after duodenal and oral administrations, respectively. These preliminary results are encouraging with a view to continuing to study this β-cyclodextrin nanosponge technology for the oral administration of insulin and extending this approach to other proteins of pharmaceutical interest.

History of Cyclodextrin Nanosponges

Nowadays, research in the field of nanotechnology and nanomedicine has become increasingly predominant, focusing on the manipulation and development of materials on a nanometer scale. Polysaccharides have often been used as they are safe, non-toxic, hydrophilic, biodegradable and are low cost. Among them, starch derivatives and, in particular, cyclodextrin-based nanosponges (CD NSs) have recently emerged due to the outstanding properties attributable to their peculiar structure. In fact, alongside the common polysaccharide features, such as the presence of tunable functional groups and their ability to interact with biological tissues, thus giving rise to bioadhesion, which is particularly useful in drug delivery, what makes CD NSs unique is their three-dimensional network made up of crosslinked cyclodextrin units. The name “nanosponge” appeared for the first time in the 1990s due to their nanoporous, sponge-like structure and responded to the need to overcome the limitations of native cyclodextrins (CDs), particularly their water solubility and inability to encapsulate charged and large molecules efficiently. Since CD NSs were introduced, efforts have been made over the years to understand their mechanism of action and their capability to host molecules with low or high molecular weight, charged, hydrophobic or hydrophilic by changing the type of cyclodextrin, crosslinker and degree of crosslinking used. They enabled great advances to be made in various fields such as agroscience, pharmaceutical, biomedical and biotechnological sectors, and NS research is far from reaching its conclusion. This review gives an overview of CD NS research, focusing on the origin and key points of the historical development in the last 50 years, progressing from relatively simple crosslinked networks in the 1960s to today’s multifunctional polymers. The approach adopted in writing the present study consisted in exploring the historical evolution of NSs in order to understand their role today, and imagine their future.

A Comprehensive Patent Review on β-cyclodextrin Cross-linked Nanosponges for Multiple Applications

BACKGROUND

Currently, the most important challenge in the development of therapeutics and actives is their poor aqueous solubility and bioavailability.

OBJECTIVE

The low aqueous solubility, poor pharmacokinetic properties, and bioavailability associated with novel actives manifest in numerous challenges in the formulation of conventional dosage forms like tablets, capsules, suspensions, emulsions, etc. Nanosponges are a novel class of drug delivery system capable of encapsulating or entrapping both lipophilic and hydrophilic drugs. Target-specific drug delivery and controlled drug release are the advantages offered by nanosponges which make them a promising anti-tumor drug delivery system.

METHODS

Nanosponges are colloidal structures comprising solid nanoparticles with cavities and meshlike structures for encapsulation of wide varieties of substances like antineoplastic agents, proteins and peptides, volatile oils, genetic material, etc. The methods of preparation of β-cyclodextrin-based nanosponges include solvent evaporation method, emulsion solvent evaporation method, ultrasound-assisted synthesis, hyper cross-linked cyclodextrin and interfacial phenomenon method. A large variety of nanosponges- based formulations are available in the market and some formulations of prostavastin, brexin, glymesason, mena-gargle, etc. are under clinical trials.

RESULTS

Nanosponges possess potential applications in target site-specific drug delivery to liver, spleen, and lungs. Due to the surface functionalization, nanosponges show broad applications in water purification, protein delivery, chemical sensors, detection of explosives, agriculture, etc. In the near future, nanosponges-based products will capture a huge market for commercialization due to their improved properties and advantages.

CONCLUSION

This review provides an account of the patents related to nanosponges (2006-2018) and covers the broad applications of β-cyclodextrin-based nanosponges, their roles in vaccine delivery, cancer therapy, fire engineering, water purification, etc.

Bio-inspired nano-engineered strip for semiquantitative FeNO analysis

A point-of-care, non-invasive, low-cost and sensitive nano-biodiagnostic is needed in today's age for rapid and accurate self-diagnosis as well as for the management of asthma, which is advantageous for low resource areas where asthma is prevalent. The objective of this research work was to prepare the miniature, nanosponges coated paper strip to detect the asthma using certain biomarkers present in exhaled air. The asthma biomarker, nitric oxide present in exhaled air (FeNO) was chosen, which on reaction with nanosponges of diazotizing agent gave significant color change. The pyromellitic anhydride cross-linked β-cyclodextrin-based nanosponges of sulfanilamide and N-(1-naphthyl) ethylenediamine dihydrochloride were prepared using a polymer condensation method and coated on Whatman filter paper strip (1 × 5 cm2). The thickness of coating was found to be uniform (400 ± 50 μm) which was determined using SEM analysis. The Hue-Saturation-Value scale was used to detect the color change using a smartphone app. We also investigated the performance of a nano-engineered paper strip by comparing this with commercially available, FDA approved FeNO analyzer-NIOX MINO. Our findings demonstrated no significant difference in results obtained using both the techniques. Besides good repeatability, the paper strip showed increasing saturation with NO concentration and the capacity to detect the biomarker down to mean value of 20.33 ppb level. The successful validation and method comparison indicated that a bioinspired strip can provide on-site analysis and daily monitoring for diagnosis and management of asthma.