فصلنامه دنیای نانو
پیاپی 72 (پاییز 1402)

In this study, we have evaluated gamma ray and neutron shielding of platinum carbon nanotubes using Geant 4 Monte Carlo simulator in the photon energy range of 15-0.015 (𝑀𝑒𝑉) . We have calculated the mass attenuation coefficient, the half value layer, the tenth value layer, the mean free path and the ratio of the linear attenuation coefficient of Compton scattering to the total linear attenuation coefficient and the remove cross section of fast neutrons, which is necessary to check the performance of a shield for these parameters. XMuDat program was used to validate the data. The Geant4 results are in good agreement with the values obtained from the XMuDat program. We have also analyzed them. Finally, the results obtained for nanomaterials have been depicted in suitable forms. At the end, suggestions for using these nanomaterials in places where there are restrictions on weight, mechanical stability and strength are given .

The perishable nature of fruits and vegetables limits their postharvest storage in natural conditions; therefore, postharvest management of these products is necessary in order to reduce losses and ensure their global supply. Nanotechnology is one of the emerging preservation techniques in various industries, including the food industry, which has had extensive innovative applications in various sectors of the food industry, including production, processing, and packaging. In this study, the conventional techniques of postharvest storage and their limitations are discussed, and the use of nanotechnologies such as nanoparticles, nanocoating, nanolaminate, nanosensor and nanobiosensor to increase the quality and shelf life of fruits and vegetables is examined. Nanoparticles, as an active system, have been widely used, the most important of which are antimicrobial properties. Nanocoating and nanolaminates, with their barrier function, maintain the quality and increase the shelf life of food products, and nanosensors and nanobiosensors are used to control quality changes and detect pathogens, toxins, pesticides, and other foreign substances. Therefore, with the development of nanotechnology, we can expect that this knowledge, in the stages of postharvest storage, transportation and processing of products, by providing unique and specific capabilities compared to conventional methods, will pave the way for solving many barriers in the agricultural sector.

Complications regarding the treatment of cutaneous wounds bring about numerous social and economic problems for both patients and healthcare systems. Conventional wound dressings do not often fulfill the clinical requirements; therefore, smart, multifunctional wound dressings with potential to interact with the wound microenvironment are being developed to improve the process of wound healing. Various sensors and smart materials, namely stimuli-responsive materials are implemented in the development of such wound dressings to improve the efficacy and the speed of the wound healing process. In this review article, recent advances regarding smart wound dressings including biomechanical wound dressings, stimuli-responsive wound dressings, self-removal wound dressings, self-healing wound dressings for motional wounds and multifunctional wound dressings with monitoring capacity have been investigated. Furthermore, the utilized smart materials in these wound dressings in particular nanomaterials have been introduced. Finally, challenges with respect to the application of such wound dressings and prospective of the future advancements have been discussed.

Catechol is an important environmental pollutant. Therefore, its quick and accurate measurement is so important. This article reported a selective and sensitive electrochemical method for determination of catechol in real samples with the help of a carbon paste electrode modified with multi-walled carbon nanotubes (MWCNTs/CPE). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to investigate the electrochemical behavior of catechol. The modified electrode showed excellent electrocatalytic properties towards catechol redox. Analytical parameters such as linearity range, selectivity, reproducibility, and stability were investigated. After optimizing the experimental conditions, the peak current of catechol in 0.1 M phosphate buffer solution (pH = 7) was linear in the concentration range of 0.5 - 200 μM. The detection limit was 0.1 μM (S/N = 3). In addition, the proposed sensor was successfully used to detection of catechol in real samples with satisfactory recovery (0.96 -102.4 %), which indicates the efficiency of the developed method in practical applications.

Plasma printing techniques are being developed as a modern approach for depositing different functional materials. In this work, a nonthermal plasma jet working in atmospheric pressure was employed to print silver nanoparticles on flexible polyester fabric substrates. Atomized droplets of silver nitrate solution were exposed to plasma reducing them to silver nanoparticles, which were printed on the substrates in a controlled condition. X-ray diffraction results confirmed the deposition of face-center cubic nanoparticles on the substrates. Field-enhanced electron scanning microscopy images demonstrated that these nanoparticles have an almost spherical shape. Surface-enhanced Raman scattering (SERS) responses of the coated substrates were investigated using a Raman marker of Rhodamine B. SERS performance for coated fabrics printed in various precursor concentrations and printing durations was investigated. The best performance corresponded to the fabric printed with a precursor of 24mM concentration and a printing time of 5min. Finally, Ag-printed fabrics were used to detect sulfite remainders of SO2-treated raisins showing promising potential in trace analysis.

Comprehensive survey of the previous research on targeted medicines shows that transdermal drug delivery systems, despite all the advantages they have, are still not responsive to drugs with high daily dosages and in a targeted manner, and there is a need to design systems for drugs with optimal dosages. In fact, the amount of drug loading in these systems is one of the problems that must be solved. The purpose of using microneedles is to deliver targeted medicine in a specific amount to a specific area. Among different microneedles, biodegradable polymer microneedles are of particular importance and have been the subject of many new studies. In the present study, an attempt has been made to prepare a comprehensive literature review about the targeted drug delivery of nanomedicines and nanoparticles for the treatment of tumors and cancerous tissues by drug delivery through the skin. In addition, the production methods of microneedles have been investigated.