Nanoporous Carriers Research Articles

Nanobiocatalysis: Approach and Applications in Drug Development and Sensing.

Enzymes play a pivotal role in the human body, but their potential is not limited to just that. Scientists have successfully modified these enzymes as nanobiocatalysts or nanozymes for industrial or commercial use, either in the food, medicine, biotech or even textile industries. These nanobiocatalysts and nanozymes offer several advantages over enzymes, like better stability, improved shelf-life, increased percentage yield, and reuse potential, which is very difficult with normal enzymes. The various techniques of NBC synthesis using immobilization techniques like adsorption, covalent binding, affinity immobilization, and entrapment methods are briefly discussed. The enzymes are either entrapped or adsorbed on the nanocarrier matrices, which can be nanofibers, nanoporous carriers, or nanocontainers as nanobiocatalysts. We also highlight the challenges the nanobiocatalyst overcomes in the industrial production of some drugs like sitagliptin, montelukast, pregabalin, and atorvastatin. Also, the inactivation of an organophosphate or opioid poisoning treating agent, SSOPOX nanohybrid, is discussed in this paper. Nanozymes are intrinsic enzyme-like compounds, and they also show wide application in themselves. Their GQD/AGNP nanohybrid shows antibacterial potential; they can also be utilized in optical sensing to detect small molecules, ions, nucleic acids, proteins, and cancer cells. In this paper, various applications of these NBCs have been discussed, and their potential applications with examples are also mentioned. Nanoenzymes can address targeted drug delivery via the controlled release of drugs to increase the efficacy of anticancer drugs that minimize damage to healthy tissue or cells.

Hybrid systems based on avobenzone–wrinkled mesoporous silica as ingredients of sunscreen formulations

Excessive exposure to solar radiation causes skin reddening, and sunburn, may accelerate photoaging processes, and lead to neoplastic changes. Therefore, it is recommended to apply cosmetic formulations containing UV protection filters. In recent years, doubts have arisen regarding the safety of certain chemical sunscreen agents that can penetrate the deeper layers of the skin, undergo photodegradation, generate allergies, and affect the endocrine system. The aim of this study was to develop a strategy to limit the permeation of avobenzone from emulsions. Wrinkled mesoporous silicas modified with zinc oxide and/or aminosilane were synthesized, characterized, and next applied as the carriers for the selected UV filter – avobenzone. The introduction of organic groups and ZnO did not disturb the wrinkled morphology of materials, but it changed the textural parameters due to the blocking of micropores. The modification of the wrinkled mesoporous silica had a positive effect on reducing avobenzone rate of desorption. The smallest amount of avobenzone was released from wrinkled mesoporous silica modified with zinc oxide. The release of avobenzone from nanocarriers followed the Korsmeyer-Peppas model, while the diffusion from emulsion was based on the Higuchi model. It was proved that the introduction of avobenzone to functionalized wrinkled mesoporous silica materials reduced the diffusion process of avobenzone from cosmetic emulsions. Nanoporous carriers may help solve the problems related to transepidermal penetration and the potential impact of UV filters on the endocrine system.

Nanoporous SiOx plasma polymer films as carrier for liquid‐infused surfaces

AbstractLiquid‐infused surfaces are based upon the infusion of a liquid phase into a porous solid material to induce slippery and repellent character. In this context, porous SiOx plasma polymer films represent a relevant candidate for a robust nanoporous carrier layer. Intermittent low‐pressure plasma etching of O2/hexamethyldisiloxane‐derived coatings is investigated to enhance the intrinsic porosity inherent to residual hydrocarbons in the silica matrix. Simulations of the resulting Si–O ring network structure using reactive molecular dynamics indicate formation of interconnected voids with Si–OH functionalized pore walls allowing water penetration with almost Fickian diffusive behavior. The corresponding porosity of up to 18%, well agreeing with simulations, Fourier‐transform infrared spectroscopy, and ellipsometry measurements, was found to be suitable for the liquid infusion of polyethylene glycol molecules into about 80 nm thick SiOx films providing ongoing lubricating properties, thus revealing their suitability as liquid‐infused surfaces.

Synthesis and Characterization of Nanoporous Carbon Carriers for Losartan Potassium Delivery.

Losartan potassium is most commonly used for the treatment of hypertension. In recent years, new applications of this drug have emerged, encouraging the design of novel nanoporous carriers for its adsorption and release. The purpose of this study was to synthesize ordered mesoporous carbon vehicles via a soft-templating method altered with the use of nitrogen precursors and via a hard-templating method followed by chitosan functionalization. As a result, the materials obtained differed in nitrogen content as well as in the number of total surface functional groups. The impact of the modification on the physicochemical properties of carbon carriers and their interaction with losartan potassium during adsorption and release processes was examined. The materials were characterized by various morphologies, specific surface areas (101–1180 m2 g−1), and the amount of acidic/basic oxygen-containing functional groups (1.26–4.27 mmol g−1). These features, along with pore sizes and volumes, had a key effect on the sorption capacity of carbon carriers towards losartan potassium (59–161 mg g−1). Moreover, they contributed to the differential release of the drug (18.56–90.46%). Losartan potassium adsorption onto the surface of carbonaceous materials was mainly based on the formation of hydrogen bonds and π–π interactions and followed the Langmuir type isotherm. It has been shown that the choice of the method of carbon carriers’ synthesis and their modification allows for the precise control of the kinetics of the losartan potassium release from their surface, resulting in rapid or sustained drug liberation.

Cu-BTC metal-organic framework as a biocompatible nanoporous carrier for chlorhexidine antibacterial agent.

Antibacterial materials are an essential part of modern life and many efforts have been made to find a new and effective type of them. In this study, chlorhexidine (CHX) was loaded on Cu-BTC metal-organic framework (MOF), that both of them are known to have antibacterial properties. The antibacterial properties of Cu-BTC, CHX and CHX@Cu-BTC were investigated against Gram-positive and Gram-negative bacteria. Agar well-diffusion method and MIC test showed that CHX@Cu-BTC has high antibacterial activity. Characterization methods, such as FT-IR, XRD, N2 adsorption-desorption isotherm, TGA, SEM, EDX, TEM and zeta potential, were employed to characterize their structures. Cu-BTC MOF nanoparticles were synthesized and used as nanoporous carriers for chlorhexidine. The loading was about 10%, which was absorbed into the pores. Antibacterial activity was investigated against Gram-negative and Gram-positive bacteria by Agar well diffusion method and MIC (minimal inhibitory concentration) assay. The CHX@Cu-BTC had synergistic antibacterial activity of Cu-BTC and chlorhexidine.

A Corollary of Nanoporous Carrier Drug Delivery System: An Updated Perspective

Nanosponges have come into sight as one of the most promising fields of science because of their perceived applications in controlled drug delivery. It has been increasingly investigated to achieve targeted and sustained release of drugs. Nanosponges are one of the novel drug delivery system, which is gaining popularity now days because of their perceived application in controlled and site-specific drug delivery. The fundamental appeal of the nanosponge technology arises from the difficulty experienced with conventional formulations in releasing active ingredients over an extended period of time, unpleasant odor, greasiness and skin irritation. They are tiny sponge-like spherical particles with a large porous surface and are believed to contribute towards reduced side effects, improved stability, increased elegance and enhanced formulation flexibility. The present investigation in the appraisal describes nanosponge technology embracing its method of preparation, characterization, in-vitro and in-vivo evaluation methods along with recent research and future potential.

Surface Heterogeneous Nucleation-Mediated Release of Beta-Carotene from Porous Silicon.

We demonstrate that the release of a poorly soluble molecule from nanoporous carriers is a complex process that undergoes heterogeneous surface nucleation events even under significantly diluted release conditions, and that those events heavily affect the dynamics of release. Using beta-carotene and porous silicon as loaded molecule and carrier model, respectively, we show that the cargo easily nucleates at the pore surface during the release, forming micro- to macroscopic solid particles at the pores surface. These particles dissolve at a much slower pace, compared to the rate of dissolution of pure beta-carotene in the same solvent, and they negatively affect the reproducibility of the release experiments, possibly because their solubility depends on their size distribution. We propose to exploit this aspect to use release kinetics as a better alternative to the induction time method, and to thereby detect heterogenous nucleation during release experiments. In fact, release dynamics provide much higher sensitivity and reproducibility as they average over the entire sample surface instead of depending on statistical analysis over a small area to find clusters.

Development, In Vitro Characterization, and In Vivo Toxicity Evaluation of Chitosan-Alginate Nanoporous Carriers Loaded with Cisplatin for Lung Cancer Treatment.

Polysaccharide-based aerogels are promising drug carriers. Being nanoporous with a high specific surface area allows their use as a drug vehicle for various delivery routes. Intratracheal and intravenous administration of free cisplatin causes toxicity in the rat liver, lungs, and kidneys. In this work, microspherical particles based on alginate-chitosan without a traditional crosslinker were evaluated for targeted delivery of cisplatin by intratracheal administration. The aerogel particles were prepared using the emulsion gelation method, followed by supercritical carbon dioxide extraction. Loading of cisplatin on the prepared porous particles was performed by impregnation using supercritical fluid technology. The prepared carrier and the loaded drug were evaluated for drug content, release, and in vivo acute and subacute toxicity. Cisplatin was successfully loaded (percent drug loading > 76%) on the prepared carrier (particle size = 0.433 ± 0.091μm) without chemically interacting with the carrier and without losing its crystal form. Sixty percent of cisplatin was released within 2h, and the rest was loaded inside the polymer pores and had a sustained first-order release over 6h. Loading cisplatin on the carrier developed herein reduced the cisplatin lung toxicity but increased the liver toxicity after intratracheal administration with nephrotoxicity being proportional to cisplatin dose in case of carrier-loaded cisplatin. Moreover, loading cisplatin on the carrier significantly reduced mortality rate and prevented weight loss in rats as compared to free cisplatin in subacute studies after intratracheal administration. Thus, the developed carrier showed high potential for targeted delivery of cisplatin for lung cancer treatment by inhalation. Graphical abstract.

Nanoporous Microsponge Particles (NMP) of Polysaccharides as Universal Carriers for Biomolecules Delivery.

Different polysaccharides—namely dextran, carboxymethyl dextran, alginate, and hyaluronic acid—were compared for the synthesis of nanoporous microsponges particles (NMPs) obtained from a one-pot self-precipitation/cross-linking process. The morphologies and sizes of the NMPs were evaluated comparatively with respect to polymer-to-polymer and cross-linker solvents (water-based vs. DMSO). We found that the radial distribution of the polymer in the near-spherical NMPs was found to peak either at the core or in the corona of the particle, depending both on the specific polymer or the solvent used for the formation of NMPs. The NMP porosity and the swelling capability were evaluated via scanning electron microscopy (SEM). The degradation study indicated that after 10 h incubation with a reducing agent, approximately 80% of the NMPs were disassembled into soluble polysaccharide chains. The adsorption and release capacity of each type of NMP were evaluated using fluorescently labeled bovine serum albumin and lysozyme as model proteins, highlighting a release time typically much longer than the corresponding adsorption time. The dependence of the adsorption-release performance on pH was demonstrated as well. Confocal microscopy images allowed us to probe the different distribution of labeled proteins inside the NMP. The safety and non-cytotoxicity of NMPs were evaluated after incubation with fibroblast 3T3 cells and showed that all types of NMPs did not adversely affect the cell viability for concentrations up to 2.25 μg/mL and an exposure time up to 120 h. Confocal microscopy imaging revealed also the effective interaction between NMPs and fibroblast 3T3 cells. Overall, this study describes a rapid, versatile, and facile approach for preparing a universal non-toxic, nanoporous carrier for protein delivery under physiological conditions.

Verapamil delivery systems on the basis of mesoporous ZSM-5/KIT-6 and ZSM-5/SBA-15 polymer nanocomposites as a potential tool to overcome MDR in cancer cells

ZSM-5/KIT-6 and ZSM-5/SBA-15 nanoparticles were synthesized and further modified by a post-synthesis method with (CH2)3SO3H and (CH2)3NHCO(CH2)2COOH groups to optimize their drug loading and release kinetic profiles. The verapamil cargo drug was loaded by incipient wetness impregnation both on the parent and modified nanoporous supports. Nanocarriers were then coated with a three-layer polymeric shell composed of chitosan-k-carrageenan-chitosan with grafted polysulfobetaine chains. The parent and drug loaded formulations were characterized by powder XRD, N2 physisorption, thermal analysis, AFM, DLS, TEM, ATR-FT-IR and solid state NMR spectroscopies. Loading of verapamil on such nanoporous carriers and their subsequent polymer coating resulted in a prolonged in vitro release of the drug molecules. Quantum-chemical calculations were performed to investigate the strength of the interaction between the specific functional groups of the drug molecule and (CH2)3SO3H and CH2)3NHCO(CH2)2COOH groups of the drug carrier. Furthermore, the ability of the developed nanocomposites to positively modulate the intracellular internalization and thereby augment the antitumor activity of the p-gp substrate drug doxorubicin was investigated in a comparative manner vs. free drug in a panel of MDR positive (HL-60/Dox, HT-29) and MDR negative (HL-60) human cancer cell lines using the Chou-Talalay method.

A Catalytic Carrier Gas Sensor Based on a Nanotube Array

To effectively monitor methane in coal mine environments, a new type of catalytic carrier gas sensor based on a nanotube array was designed and fabricated. The sensor consists of a catalytic carrier based on a nanotube array, a sensitive Pt electrode, leading wires made from Ag/Pd alloy, a standard two-pin tube shell, powder metallurgy sheets and other components. The metallurgical copper powder sheets make the sensor explosion-proof. The desired catalytic carrier based on a Al2O3 nanotube array was prepared by chemical deposition on a nanoporous carrier film. The sensitive Pt electrode was prepared by a thick-film printing process via impregnation with a chloroplatinic acid and palladium chloride solution to form the noble metal catalyst. The results show that for methane concentrations in the range of 0% to 3%, the measured output is approximately 73 5 mV, the response time is 6 seconds, and the recovery time is 5 seconds. When the CH4 concentration is in the range of 0~3.81%, the response voltage of the sensor and the concentration of CH4 exhibit a good linear relationship. The stability of the sensor was examined in a 2% CH4 environment, and the stability of the sensor drifted 0.15% after 60 days.

Synthesis of nanoporous Baghdadite by a modified sol-gel method and its structural and controlled release properties

In this research, a bimodal nanoporous Baghdadite (NB) (Ca3ZrSi2O9) was prepared by a modified sol-gel method using P123 as a surfactant. The effects of P123's contents on the structural and textural properties as well as the drug delivery behavior of NB were assessed in vitro. The usage of P123 offered a new route for the synthesis of NB. The synthesized NB samples with different amounts of P123 were studied through X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), N2 adsorption-desorption, field emission scanning electron microscopy (FESEM) equipped with energy-dispersive X-ray analysis spectroscopy (EDAX) and transmission electron microscopy (TEM). The results showed that a single-phase Baghdadite was obtained by this new method at the calcination temperature of 800 °C. It was found that an increase in P123's content up to 0.025 mol changed the morphology of NB samples from mountain-like to needle-like. The potential application of NB samples as drug delivery agents was assessed by estimating their release properties up to 240 h. This research revealed that the synthesized Baghdadite could be used as a potential nanoporous carrier with controlled release capability in bone tissue regeneration.

Nanoporous mannitol carrier prepared by non-organic solvent spray drying technique to enhance the aerosolization performance for dry powder inhalation

An optimum carrier rugosity is essential to achieve a satisfying drug deposition efficiency for the carrier based dry powder inhalation (DPI). Therefore, a non-organic spray drying technique was firstly used to prepare nanoporous mannitol with small asperities to enhance the DPI aerosolization performance. Ammonium carbonate was used as a pore-forming agent since it decomposed with volatile during preparation. It was found that only the porous structure, and hence the specific surface area and carrier density were changed at different ammonium carbonate concentration. Furthermore, the carrier density was used as an indication of porosity to correlate with drug aerosolization. A good correlation between the carrier density and fine particle fraction (FPF) (r2 = 0.9579) was established, suggesting that the deposition efficiency increased with the decreased carrier density. Nanoporous mannitol with a mean pore size of about 6 nm exhibited 0.24-fold carrier density while 2.16-fold FPF value of the non-porous mannitol. The enhanced deposition efficiency was further confirmed from the pharmacokinetic studies since the nanoporous mannitol exhibited a significantly higher AUC0-8h value than the non-porous mannitol and commercial product Pulmicort. Therefore, surface modification by preparing nanoporous carrier through non-organic spray drying showed to be a facile approach to enhance the DPI aerosolization performance.

Application of nanoporous silicas as adsorbents for chlorinated aromatic compounds. A comparative study

The removal of two selected environmental pollutants such as 2,4-dichlorophenoxyacetic acid (2,4-D) and Triclosan (TC) was examined by adsorption experiments on the modified SBA-15 and MCF mesoporous silicas. Mesoporous adsorbents were modified by a grafting process with (3-aminopropyl)triethoxysilane (APTES) and 1-[3-(trimethoxysilyl)propyl]urea (TMSPU). Mesoporous materials were synthesized and characterized by N2 adsorption–desorption experiment, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis and adsorption studies. The results show that both APTES-functionalized SBA-15 and MCF nanoporous carriers are potentially good adsorbents for the removal of 2,4-D in a wide range of concentrations from 0.1 to 4mg/cm3. Maximum adsorption capacity of as-modified adsorbents for 2,4-D estimated from the Langmuir model was ~280mg/g. The ionic interaction between the adsorbent and 2,4-D seems to play a key role in the adsorption process of the pollutant on APTES-modified siliceous matrices. The efficiency of TC sorption onto all prepared mesoporous adsorbents was significantly lower as compared to the entrapment of 2,4-D. Experimental data were best fitted by the Langmuir isotherm model. The results of this study suggest that mesoporous silica-based materials are promising adsorbents for the removal of selected organic pollutants.

Design of Alginate-Based Aerogel for Nonsteroidal Anti-Inflammatory Drugs Controlled Delivery Systems Using Prilling and Supercritical-Assisted Drying

In this study, a novel preparation method for alginate-based aerogels charged with nonsteroidal anti-inflammatory drugs (NSAIDs) was developed using prilling in combination with supercritical fluid technique. Nanoporous carriers were prepared by laminar jet breakup of drug/alginate solutions or suspensions followed by cross-linking in ethanol or aqueous CaCl(2) solutions, water replacement, and supercritical-CO(2) -assisted drying. A substantial drug loss was observed for highly soluble ketoprofen lysinate, whereas encapsulation efficiency was satisfying for slightly soluble ketoprofen. The tandem technique successfully produced almost spherical aerogels (sphericity coefficient 0.97-0.99) in narrow size distribution with reduced particle shrinkage and smooth surface (surface roughness 1.10-1.13); the internal porous texture of the parent hydrogels was preserved and appeared as a network of nanopores with diameters around 200 nm. Drug release profiles were monitored using a pH change method to evaluate the possible application of the aerogels as fast dissolving NSAIDs formulation. Aqueous cross-linking led to aerogels encapsulating ketoprofen in the amorphous form and with an enhanced burst effect in simulated gastric fluid (75% in 30 min), whereas ethanol cross-linking produced aerogels embedding drug in crystal clusters with slower dissolution rate. The system appears an interesting potential carrier for the fast delivery of slightly soluble drugs in the upper gastrointestinal tract.

Selective and ATP-driven transport of ions across supported membranes into nanoporous carriers using gramicidin A and ATP synthase

We report a robust and versatile membrane protein based system for selective uptake and release of ions from nanoporous particles sealed with ion-tight lipid bilayers of various compositions that is driven by the addition of ATP or a chemical potential gradient. We have successfully incorporated both a passive ion channel-type peptide (gramicidin A) and a more complex primary sodium ion transporter (ATP synthase) into the supported lipid bilayers on solid nanoporous silica particles. Protein-mediated controlled release/uptake of sodium ions across the ion-tight lipid bilayer seal from or into the nanoporous silica carrier was imaged in real time using a confocal laser scanning microscope and the intensity changes were quantified. ATP-driven transport of sodium ions across the supported lipid bilayer against a chemical gradient was demonstrated. The possibility of designing durable carriers with tight lipid membranes, containing membrane proteins for selective ion uptake and release, offers new possibilities for functional studies of single or cascading membrane protein systems and could also be used as biomimetic microreactors for controlled synthesis of inorganic multicomponent materials.

Sedimentation stability of aqueous dispersions of nanodiamond agglomerates

The electric conductivity and sedimentation stability of aqueous dispersions of nanodiamond agglomerates are studied. The properties and stability of dispersions were shown to be significantly affected by the pretreatment of particles. The particle size distribution was determined by means of optical microscopy. The sedimentation kinetics of nanodiamond particles in aqueous solutions was studied. The sedimentation kinetic curves showed two sections of fast and slow sedimentation. The obtained results are necessary to develop the technology of nanoporous carriers in analytical and preparative chromatography

The self-assembling and application of inorganic antibacterial material made of natural nanoporous carrier

The inorganic antimicrobial material was inhibited to the microbes with the added metal ion, Zn. The primary wet product carrying 5%–10% zinc ion was generated under the following conditions: temperature was 95 °C, solution zinc concentration was 1.2–2.0 mol/L, and the ratio of Zn solution to zeolite weight was 5: 1. The final stable product was manufactured after baking in an oven for 1–3 h at the temperature of 500–900 °C. The baked material was tested for its disinfection effectiveness and coloring effect when mixed with paint coating. Based on the final batch of tests, the zinc content of this anti-microbial product was further optimized.

Vitrification from solution in restricted space: Formation and stabilization of amorphous nifedipine in a nanoporous silica xerogel carrier

Purpose The goal was to find thermodynamic criteria that must be satisfied in order to prevent formation of crystalline state of drugs within a confined space (e.g., nanopores of inorganic solid). Similarly, criteria that lead to stabilization of amorphous drug within such pores were investigated. Methods In the theoretical part, the classical thermodynamics of nucleation is applied to the conditions of a restricted space. The theoretical findings are verified using porous silica as a carrier and nifedipine as a model drug. The amorphicity of the latter is checked using XRD and thermal analysis (DTA, DSC) in combination with BET measurements. Results It is shown that there exists a critical pore radius of a host below which the entrapped substance will solidify in an amorphous form. There also exists a critical pore radius below which the entrapped amorphous solid will not be able to crystallize. Specifically, incorporation of NIF into a silica xerogel with an average pore diameter of about 2.5 nm produces and stabilizes its amorphous form. Conclusion Entrapment of drugs into solid nanoporous carriers could be regarded as a potentially useful and simple method for production and/or stabilization of non-crystalline forms of a wide range of drugs.

Preparation of Nanoporous Super Thermal Insulation Material Compounded with Xonotlite-SiO<sub>2</sub>-Aerogel and Characterization of the Pore Structure

Ultra-light calcium silicate material constructed with fibrous xonotlite crystals has an advantage of low-thermal conduction coefficient. But the microporous structure can hardly make a better performance in terms of super thermal insulation. Although nanoporous structure of SiO2-aerogel satisfies the requirement, its tenacity is not strong enough to produce by itself blocky super thermal insulation material. This research, thus proposes to apply SiO2-aerogel as nanoporous carrier in the process of preparation, with Ultra-light calcium silicate material constructed with fibrous xonotlite crystals as the matrix so as to prepare nanoporous super thermal insulation material compounded with Xonotlite-SiO2-aerogel via so-gel method and ethanol supercritical drying. SEM and pore size distribution techniques were here applied to characterize the morphology and pore structure of the composite material. The results show that the SiO2-aerogels were better distributed in pore of calcium silicate matrix, with the pore size distribution of composite ranging from 10 nanometers to 50 nanometers, and average pore size less then 20 nm.