Recent Patents on Nanotechnology - Volume 17, Issue 2, 2023

Background: Recently, nano-drug delivery systems have become an integral part of the most novel drug delivery systems and have gained considerable importance owing to various advantages such as carriers for poorly soluble drugs, targeting molecules at the desired site, protection from degradation etc. Objective: One of the most studied areas of nanotechnology is nanosponges. The objective of this review was to extensively summarize the various strategies for the preparation, characterization and applications of nanosponges. Methods: In the current mini-review, we conducted a systemic search of the literature and patent inventions focusing on nanosponges. The summary of the search was inclusive of various aspects of nanosponges, such as drug characteristics to be considered while incorporating in nanosponges, other crucial additives during formulation of nanosponges, methods of preparation, characterization and applications of nanosponges in pharmaceuticals. Results: Nanosponges are nanocarriers for both lipophilic and hydrophilic drugs. These are prepared by different methods such as emulsion-solvent evaporation, solvent method, melting method, ultrasound assisted method etc., and all these methods were less time consuming, more economical and evaluated by sophisticated techniques available for routine analysis. These are among the most feasible alternative to address several formulation difficulties associated with the physicochemical properties of the drug. The porous nature and small particle size are vital properties of the nanosponges that contribute crucially to correcting the drawbacks of the drug. The properties of the nanosponges can be enhanced when combined with cyclodextrins. Extensive research work has been carried out in past to explore cyclodextrin based nanosponges. Besides, it is also used for smart targeting of tumors and for drug release in a sustainable pattern. Nanosponges can be prepared by simple methods. These can be tuned to release the drug by different routes so as to achieve the maximum benefits of the drug. Conclusion: Huge amount of research has been carried out on nanosponges as drug carrier. The method of preparation and characterization of nanosponges are quite economical and routinely available. Owing to potential benefits and probable applications, these can be used as efficient carriers for certain drugs. The authors expect that the current review will guide the investigation of the nanosponges as nanodrug delivery systems.

Background: Nanomaterial is one of the most used materials for various gas sensing applications to detect toxic gases, human breath, and other specific gas sensing. One of the most important applications of nanomaterial based gas sensors is biosensing applications. In this review article, the gas sensors for biosensing are discussed on the basis of crystalline structure and different categories of nanomaterial. Methods: In this paper, firstly, rigorous efforts have been made to find out research questions by going through a structured and systematic survey of available peer reviewed high quality articles in this field. The papers related to nanomaterial based biosensors are then reviewed qualitatively to provide substantive findings from the recent developments in this field. Results: In this mini-review article, firstly, classifications of nanomaterial gas sensors have been presented on the basis of the crystalline structure of nanomaterial and different types of nanomaterial available for biosensing applications. Further, the gas sensors based on nanomaterial for biosensing applications are collected and reviewed in terms of their performance parameters such as sensing material used, target gas component, detection ranges (ppm-ppb), response time, operating temperature and method of detection, etc. The different nanomaterials possess slightly different sensing and morphological properties due to their structure; therefore, it can be said that a nanomaterial must be selected carefully for a particular application. The 1D nanomaterials show the best selectivity and sensitivity for gases available in low concentration ranges due to their miniaturised structure compared to 2D and 3D nanomaterials. However, these 2D and 3D nanomaterials also so good sensing properties compared to bulk semiconductor materials. The polymer and nanocomposites which are also discussed in this patent article have opened the door for future research and have great potential for new generation gas sensors for detecting biomolecules. Conclusion: These nanomaterials extend great properties towards sensing the application of different gases for a lower concentration of particular gas particles. Nano polymer and nanocomposites have great potential to be used as gas sensors for the detection of biomolecules.

Background: Studies on the surface functionalization of flexible carbon fibers without any substrate by using cost-effective, fast, and practical processes that may provide antibacterial properties to carbon fiber have received great importance recently. Objective: The objective of this patent study is to obtain zinc oxide nanostructures functionalized carbon fibers by a facile, cheap, fast, and repeatable method, and to show their effective antibacterial activity. Methods: Electroplating and electrochemical anodization were used to synthesize zinc oxide nanostructures on carbon fiber surfaces, respectively, and their antibacterial properties were studied by zone inhibition test against Staphylococcus aureus and Pseudomonas aeruginosa. Results: The zinc oxide nanostructures on carbon fiber surfaces were successfully synthesized in minutes, and they exhibited effective antibacterial properties against Staphylococcus aureus and Pseudomonas aeruginosa. The morphological properties of the nanocomposite were studied using scanning electron microscopy, which showed that ZnO on the CF surface exhibits a flake-like nanostructure. Fourier transform infrared spectrophotometer, x-ray diffraction spectroscopy, Raman spectroscopy, and x-ray photoelectron spectroscopy were used to analyze the composite's compositional, structural, crystallographic, and spectral characteristics. The results from all analyses were in a good agreement, indicating that the wurtzite crystalline ZnO nanostructure was successfully produced on the CF surface. Conclusion: As a consequence, a method for the surface functionalization of carbon fiber using zinc oxide nanostructures has been developed that is feasible, low-cost, rapid, and repeatable. The flexible nanocomposite structure has a significant potential to be employed as a scaffold in sensor technology, wearable devices, and particularly in medical textiles due to its antibacterial and woven-able properties.

Background: Topical delivery of therapeutic agents is considered beneficial due to various advantages like ease of administration, avoidance of the first-pass effect, and improved patient compliance. Therefore, scientists around the globe are exploring this route for the delivery of drugs nowadays. Objective: The present patent investigation aimed to prepare, optimize, and characterize the urealoaded microsponges for efficient topical delivery in vitro. Methods: Urea-loaded ethylcellulose microsponges were prepared using quasi emulsion solvent diffusion technique and optimized using Box–Behnken design (BBD). Furthermore, they were characterized in-vitro using various techniques like scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis (XRD). In-vitro drug release and release kinetics analysis was also performed. Results: Urea-loaded microsponges were spherical and porous. Optimized urea loaded microsponges showed a minimum size (39.78 ± 1.98 μm), high entrapment (74.56 ± 2.8%), acceptable polydispersity index (PDI) (0.224 ± 0.081) and zeta potential (-21.9 ± 2.9 mV). These microsponges were capable of sustaining the release of urea for 24 h (91.21 ± 5.20%), and the mechanism of release was the combination of diffusion and erosion. Conclusion: The developed microsponge system could be beneficial for topical delivery of urea as it could reduce the dosing frequency of urea and increase patient compliance through its sustained release.

Background: In this patent article, a novel bismuth tungstate/preoxidized acrylonitrile/ acrylic acid (AN/AA) copolymer composite nanofiber membrane was prepared, which was used as the visible light catalyst. Methods: AN/AA copolymer was synthesized, which was electrospun with bismuth nitrate and sodium tungstate to prepare the composite nanofiber. Then the composite nanofiber was preoxidized to prepare the bismuth tungstate/preoxidized AN/AA composite nanofiber membrane containing adsorption moiety and photocatalytic active moiety. Results: The photocatalytic activity of bismuth tungstate/preoxidized AN/AA composite nanofiber membrane with different preoxidized temperature, heating rate, and holding time by catalytic degradation of methylene blue was investigated. The optimal preoxidized conditions were as follows: the preoxidized temperature was heated to 200 °C with the heating rate of 1°C/min and the holding time at this temperature was 12 h. The chemical structure and morphology of the composite nanofiber membrane were characterized by FTIR, XRD, and SEM. Conclusion: The bismuth tungstate/preoxidized AN/AA composite nanofiber membrane obtained good photocatalytic properties and reusability under visible light. The degradation rate of methylene blue by this visible light catalyst could reach 90.24% for 4.5 h, and the degradation rate remained 81.53% for 4.5 h after 5 reuses.

Background: Endothelialization in vitro is a very common method for surface modification of cardiovascular materials. However, mature endothelial cells are not suitable because of the difficulty in obtaining and immunogenicity. Methods: In this patent work, we determined the appropriate amount of copper by constructing a copper- loaded titanium dioxide nanotube array that can catalyze the release of nitric oxide, compared the effects of coupled-/soluble-copper on stem cells, and then induced stem cells to differentiate into endothelial cells. Results: The results showed that it had a strong promotion effect on the differentiation of stem cells into endothelial cells, which might be used for endothelialization in vitro. Conclusion: SEM and EDS results prove that a high content of copper ions are indeed doped onto the surface of nanotubes with small amounts of Cu release. The release of NO confirms that the release of several samples within a period of time is within the physiological concentration.

Background: The In2O3 nanowires have attracted enormous attention for gas sensor application due to their advantageous features. However, the controlled synthesis of In2O3 nanowires for gas sensors is vital and challenging because the gas sensing performance of the nanowires is strongly dependent on their characteristics. Methods: Here in this patent, we fabricated In2O3 nanowires on SiO2/Si substrate via a simple thermal vapor deposition method with the Au thin film as the catalyst. The growth temperatures were controlled to obtain desired nanowires of small size. The grown In2O3 nanowires were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. The ethanol gas sensing properties were tested under the dynamic flow of dry air and analytic gas. The synthesized In2O3 nanowires have the potential for use in ethanol gas sensor application. Results: In2O3 nanostructures grown at different temperatures ranging from 600 to 900oC have different morphologies. The sample grown at 600oC had a morphology of nanowire, with a diameter of approximately 80 nm and a length of few micrometers. Nanowires grown at 600°C were composed of oxygen (O) and indium (In) elements, with the atomic ratio of [O]/[In] = 3/5. The nanowire was a single phase cubic structure of In2O3 crystal. The In2O3 nanowire sensor showed typical n-type semiconducting sensing properties. The response decreased from 130 to 75 at 100 ppm when the working temperature decreased from 450°C to 350°C. Conclusion: The nanowires grown at 600°C by the thermal vapor deposition method had the best morphology with a small diameter of about 80 nm and a length of few micrometers. The In2O3 nanowires had a good ability to sense ethanol at varying concentrations in the range of 20 ppm to 100 ppm. The In2O3 nanowires can be used as building blocks for future nanoscale gas sensors.

Background: Titanium dioxide (TiO2) nanotubes arrays have shown tremendous application foreground due to their unique characters of structure and performance. However, the single bio-function is still the limit on cardiovascular biomaterials. Methods: The loadability function provides the possibility for the TiO2 nanotubes arrays to realize composite multifunction. The copper can catalyze the release of nitric oxide to promote the proliferation of endothelium cells and improve the anticoagulant. Also, zinc can adjust the inflammatory responses to improve anti-inflammation. Results: In this patent work, we co-doped the copper and zinc onto TiO2 nanotubes arrays to estimate the hemocompatibility, cytocompatibility and responses of inflammation. The results showed that copper and zinc could introduce better multi-biofunctions to the TiO2 nanotubes arrays for the application in cardiovascular biomaterials. Conclusion: In summary, the NTs@Cu/Zn sample as a new composite material in this study had significant biocompatibility in vascular implantation and can be used as a potential material for polymer- free drug-eluting stents.