Cyclodextrin Metal-Organic Framework as a Broad-Spectrum Potential Delivery Vehicle for the Gasotransmitters

The important role of gasotransmitters in physiology and pathophysiology suggest employing gasotransmitters for biomedical treatment. Unfortunately, the difficulty in storage and controlled delivery of these gaseous molecules hindered the development of effective gasotransmitters-based therapies. The design of a safe, facile, and wide-scale method to delivery multiple gasotransmitters is a great challenge. Herein, we use an ultrasonic assisted preparation γ-cyclodextrin metal organic framework (γ-CD-MOF) as a broad-spectrum delivery vehicle for various gasotransmitters, such as SO₂, NO, and H₂S. The release rate of gasotransmitters could be tuned by modifying the γ-CD-MOF with different Pluronics. The biological relevance of the exogenous gasotransmitters produced by this method is evidenced by the DNA cleavage ability and the anti-inflammatory effects. Furthermore, the γ-CD-MOF composed of food-grade γ-CD and nontoxic metal salts shows good biocompatibility and particle size (180 nm). Therefore, γ-CD-MOF is expected to be an excellent tool for the study of co-delivery and cooperative therapy of gasotransmitters.

Therapeutic gas delivery strategies

Gas molecules with pharmaceutical effects offer emerging solutions to diseases. In addition to traditional medical gases including O₂ and NO, more gases such as H₂ , H₂ S, SO₂ , and CO have recently been discovered to play important roles in various diseases. Though some issues need to be addressed before clinical application, the increasing attention to gas therapy clearly indicates the potentials of these gases for disease treatment. The most important and difficult part of developing gas therapy systems is to transport gas molecules of high diffusibility and penetrability to interesting targets. Given the particular importance of gas molecule delivery for gas therapy, distinguished strategies have been explored to improve gas delivery efficiency and controllable gas release. Here, we summarize the strategies of therapeutic gas delivery for gas therapy, including direct gas molecule delivery by chemical and physical absorption, inorganic/organic/hybrid gas prodrugs, and natural/artificial/hybrid catalyst delivery for gas generation. The advantages and shortcomings of these gas delivery strategies are analyzed. On this basis, intelligent gas delivery strategies and catalysts use in future gas therapy are discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

A Comparison of Different Approaches to Quantify Nitric Oxide Release from NO-Releasing Materials in Relevant Biological Media

The development of solid materials that deliver nitric oxide (NO) are of interest for several therapeutic applications. Nevertheless, due to NO’s reactive nature, rapid diffusion and short half-life, reporting their NO delivery characteristics is rather complex. The full knowledge of this parameter is fundamental to discuss the therapeutic utility of these materials, and thus, the NO quantification strategy must be carefully considered according to the NO-releasing scaffold type, to the expected NO-releasing amounts and to the medium of quantification. In this work, we explore and discuss three different ways of quantifying the release of NO in different biological fluids: haemoglobin assay, Griess assay and NO electrochemical detection. For these measurements, different porous materials, namely zeolites and titanosilicates were used as models for NO-releasing platforms. The oxyhaemoglobin assay offers great sensitivity (nanomolar levels), but it is only possible to monitor the NO release while oxyhaemoglobin is not fully converted. On the other hand, Griess assay has low sensitivity in complex biological media, namely in blood, and interferences with media make NO measurements questionable. Nevertheless, this method can measure micromolar amounts of NO and may be useful for an initial screening for long-term release performance. The electrochemical sensor enabled real-time measurements in a variety of biological settings. However, measured NO is critically low in oxygenated and complex media, giving transient signals, which makes long-term quantification impossible. Despite the disadvantages of each method, the combination of all the results provided a more comprehensive NO release profile for these materials, which will help to determine which formulations are most promising for specific therapeutic applications. This study highlights the importance of using appropriate NO quantification tools to provide accurate reports.

Porous materials as carriers of gasotransmitters towards gas biology and therapeutic applications

This review highlights the strategies employed to load and release gasotransmitters such as NO, CO and H₂S from different kinds of porous materials, including zeolites, mesoporous silica, metal–organic frameworks and protein assemblies.

New generation of nitric oxide-releasing porous materials: Assessment of their potential to regulate biological functions

Nitric oxide (NO) presents innumerable biological roles, and its exogenous supplementation for therapeutic purposes has become a necessity. Some nanoporous materials proved to be potential vehicles for NO with high storage capacity. However, there is still a lack of information about their efficiency to release controlled NO and if they are biocompatible and biologically stable. In this work, we address this knowledge gap starting by evaluating the NO release and stability under biological conditions and their toxicity with primary keratinocyte cells. Titanosilicates (ETS-4 and ETS-10 types) and clay-based materials were the materials under study, which have shown in previous studies suitable NO gas adsorption/release rates. ETS-4 proved to be the most promising material, combining good biocompatibility at 180 μg/mL, stability and slower NO release. ETS-10 and ETAS-10 showed the best biocompatibility at the same concentration and, in the case of clay-based materials, CoOS is the least toxic of those tested and the one that releases the highest NO amount. The potentiality of these new NO donors to regulate biological functions was assessed next by controlling the mitochondrial respiration and the cell migration. NO-loaded ETS-4 regulates O₂ consumption and cell migration in a dose-dependent manner. For cell migration, a biphasic effect was observed in a narrow range of ETS-4 concentration, with a stimulatory effect becoming inhibitory just by doubling ETS-4 concentration. For the other materials, no effective regulation was achieved, which highlights the relevance of the new assessment presented in this work for nanoporous NO carriers that will pave the way for further developments.

Vitamin B3 metal-organic frameworks as potential delivery vehicles for therapeutic nitric oxide

The synthesis and structural characterization of two isostructural metal (M=Ni, Co) 3D framework structure that integrate vitamin B₃ building blocks with NO delivery capabilities and low toxicity is presented. The compounds with a formula [M₂(μ₂-H₂O)(μ-vitamin B₃)₄]·2H₂O contain two crystallographic distinct divalent metal centres connected by a bridging water and carboxylate group from vitamin B₃. The porous compounds have the capability of storing and releasing nitric oxide (NO) in a slow and reversible manner, with released amounts of 2.6 and 2.0μmol NOmg_solid^-1, on the Ni and Co compound, respectively. The NO release followed a convenient slow release kinetic profile in both gas and liquid phases. Haemoglobin tests demonstrated that NO is released to the medium in a biologically active form, thus suitable to trigger the desired response in biological systems. The toxicity of the samples with and without loaded NO was evaluated from cytotoxicity tests in HeLa and HEKn cells, showing low toxicity of the compounds at concentrations below 180μgcm^-3. The overall results indicate that these bio based MOFs are of interest for therapeutic applications related with NO delivery. STATEMENT OF SIGNIFICANCE.

Comparison of different silica microporous structures as drug delivery systems for in vitro models of solid tumors

5-FU release profiles reveled to be dependent on the host structures. 5-FU DDS led to significant potentiation of the 5-FU effect in cancer cells.

Synthetic cobalt clays for the storage and slow release of therapeutic nitric oxide

Nitric oxide (NO) is one of the smallest endogenous molecules with particularly interesting aspect roles in biological systems, despite its toxicological potential.

l-Histidine-based organoclays for the storage and release of therapeutic nitric oxide

Despite its toxicity, in low concentrations, nitric oxide (NO) is a small endogenous molecule with a particularly important role in the regulation of several biochemical pathways of the human body. The potential of l-histidine-modified clays (organoclays) for storage and therapeutic release of nitric oxide was assessed. Materials were characterized by powder X-ray diffraction, TG-DSC, IR spectroscopy, and nitrogen adsorption at -196 °C. The NO storage and release kinetics was studied both in the gas and liquid phases. For some materials, improvement was observed for both the released amounts and the release profile for the organoclays in relation to the respective raw clays. Assays with HeLa cells indicated that the materials have low cytotoxicity.

Coordination polymers of ZnIIand 5-methoxy isophthalate

Four different coordination polymers were prepared by reaction of Zn(OAc)₂and 5-methoxy isophthalic acid using various aqueous/aqueous alcohol solvent systems.