Investigations of the Influences of Processing Conditions on the Properties of Spray Dried Chitosan-Tripolyphosphate Particles loaded with Theophylline

Acidified sucralfate encapsulated chitosan derivative nanoparticles as oral vaccine adjuvant delivery enhancing mucosal and systemic immunity

Oral vaccines are generally perceived to be safe, easy to administer, and have the potential to induce both systemic and mucosal immune responses. However, given the challenges posed by the harsh gastrointestinal environment and mucus barriers, the development of oral vaccines necessitates the employment of a safe and efficient delivery system. In recent years, nanoparticle-based delivery has proven to be an ideal delivery vector for the manufacture of oral vaccines. Hence, considering the above, the sucralfate acidified (SA) encapsulated N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC)/N,O-carboxymethyl chitosan (CMCS) nanoparticles (SA@N-2-HACC/CMCS NPs) were prepared, and the BSA was used as a model antigen to investigate the immune responses. The SA@N-2-HACC/CMCS NPs had a particle size of 227 ± 7.0 nm and a zeta potential of 8.43 ± 2.62 mV. The NPs displayed slow and sustained release and high stability in simulated gastric juice and intestinal fluid. RAW 264.7 macrophage-like cell line demonstrated enhanced uptake of the SA@N-2-HACC/CMCS/BSA Nps. The vaccine via oral administration markedly enhanced the residence time of BSA in the intestine for more than 12 h and elicited the production of IgG and sIgA. The SA@N-2-HACC/CMCS NPs developed here for oral administration is an excellent technique for delivering antigens and provides a path of mucosal vaccine research.

α-Chitosan and β-Oligochitosan Mixtures-Based Formula for In Vitro Assessment of Melanocyte Cells Response

Chitosan is a natural polymer with numerous biomedical applications. The cellular activity of chitosan has been studied in various types of cancer, including melanoma, and indicates that these molecules can open new perspectives on antiproliferative action and anticancer therapy. This study analyzes how different chitosan conformations, such as α-chitosan (CH) or β-oligochitosan (CO), with various degrees of deacetylation (DDA) and molar mass (MM), both in different concentrations and in CH-CO mixtures, influence the cellular processes of SK-MEL-28 melanocytes, to estimate the reactivity of these cells to the applied treatments. The in vitro evaluation was carried out, aiming at the cellular metabolism (MTT assay), cellular morphology, and chitinase-like glycoprotein YKL-40 expression. The in vitro effect of the CH-CO mixture application on melanocytes is obvious at low concentrations of α-chitosan/β-oligochitosan (1:2 ratio), with the cell's response supporting the hypothesis that β-oligo-chitosan amplifies the effect. This oligochitosan mixture, favored by the β conformation and its small size, penetrates faster into the cells, being more reactive when interacting with some cellular components. Morphological effects expressed by the loss of cell adhesion and the depletion of YKL-40 synthesis are significant responses of melanocytes. β-oligochitosan (1.5 kDa) induces an extension of cytophysiological effects and limits the cell viability compared to α-chitosan (400-900 kDa). Statistical analysis using multivariate techniques showed differences between the CH samples and CH-CO mixtures.

Spray-Dried Chitosan Hydrogel Particles as a Potential Delivery System for Benzydamine Hydrochloride

Chitosan, being a biocompatible and mucoadhesive polysaccharide, is one of the most preferred hydrogel-forming materials for drug delivery. The objectives of the present study are to obtain spray-dried microparticles based on low-molecular-weight chitosan and study their potential application as cargo systems for the orally active drug benzydamine hydrochloride. Three types of particles are obtained: raw chitosan particles (at three different concentrations), cross-linked with sodium tripolyphosphate (NaTPP) particles (at three different chitosan:NaTPP ratios), and particles coated with mannitol (at three different chitosan:mannitol ratios), all of them in the size range between 1 and 10 µm. Based on the loading efficiency and the yields of the formulated hydrogel particles, one model of each type is chosen for further investigation of the effect of the cross-linker or the excipient on the properties of the gel structures. The morphology of both empty and benzydamine hydrochloride-loaded chitosan particles was examined by scanning electron microscopy, and it was quite regular and spherical. Interactions and composition in the samples are investigated by Fourier-transformed infrared spectroscopy. The thermal stability and phase state of the drug and drug-containing polymer matrixes were tested by differential scanning calorimetry and X-ray powdered diffraction, revealing that the drug underwent a phase transition. A drug release kinetics study of the chosen gel-based structures in simulated saliva buffer (pH = 6.8) and mathematical modeling of the process were performed, indicating the Weibull model as the most appropriate one.

Cyclosporine A-loaded chitosan extra-fine particles for deep pulmonary drug delivery: In vitro and in vivo evaluation

In this study, the extra-fine dry powder inhalers (DPIs) with chitosan (CS) as carrier were successfully prepared by ionic gel method combined with spray drying technique for deep pulmonary drug delivery of Cyclosporine A (CsA), using sodium hyaluronate (SHA) and sodium polyglutamate (SPGA) as polyanions. The CsA-loaded DPIs of CS-SHA-CsA and CS-SPGA-CsA were spherical particles with wrinkles on the surface, which were more conducive to improving the aerosol properties. The aerodynamic evaluation of CS-SHA-CsA and CS-SPGA-CsA showed that the fine particle fraction (FPF) reached up to 79.22 ± 2.12% and 81.55 ± 0.43%, while the emitted fraction (EF) reached 77.15 ± 1.46% and 78.29 ± 2.10%. In addition, the mass median aerodynamic diameter (MMAD) was calculated as 1.58 ± 0.04 μm and 1.94 ± 0.02 μm for CS-SHA-CsA and CS-SPGA-CsA, indicating that they were all extra-fine particles (d < 2 μm). These in vitro aerodynamic results showed that CS-SHA-CsA and CS-SPGA-CsA could reach the smaller airways, further improving therapeutic efficiency. The cell viability on A549 cell line results showed that CS-SHA-CsA and CS-SPGA-CsA were safe to deliver CsA to lungs. The in vivo pharmacokinetics consequence proved that inhalation administration of CS-SHA-CsA and CS-SPGA-CsA could significantly improve the bioavailability of CsA in vivo compared with oral administration of Neoral®, effectively reducing the risk of a series of adverse effects caused by systemic overexposure. In addition, the safety and compatibility of DPIs using SHA, SPGA, and CS as carriers for pulmonary drug delivery was verified by in vivo repeated dose inhalation toxicity. From these findings, the extra-fine DPIs with CS as carrier could be a viable delivery option for the deep pulmonary drug delivery of CsA relative to orally administered drug.

Collagen membrane loaded with doxycycline through hydroxypropyl chitosan microspheres for the early reconstruction of alkali-burned cornea

Corneal alkali burn is one of the most devastating ophthalmic emergencies correlated with remarkable morbidity resulting in severe visual impairment. Appropriate intervention in the acute phase determines the eventual outcome for later corneal restoration treatment. Since the epithelium plays an essential role in inhibiting inflammation and promoting tissue repair, sustained anti-matrix metalloproteinases (MMPs) and pro-epithelialization are the prior remedies during the first week. In this study, a drug-loaded collagen membrane (Dox-HCM/Col) that could be sutured to overlay the burned cornea was developed to accelerate the early reconstruction. Doxycycline (Dox), a specific inhibitor of MMPs, was encapsulated in collagen membrane (Col) through hydroxypropyl chitosan microspheres (HCM) to develop Dox-HCM/Col, affording a preferable pro-epithelialization microenvironment and an in-situ controlled release. Results showed that loading HCM into Col prolonged the release time to 7 days, and Dox-HCM/Col could significantly suppress the expression of MMP-9 and -13 in vitro and in vivo. Furthermore, the membrane accelerated the corneal complete re-epithelialization and promoted early reconstruction within the first week. Overall, Dox-HCM/Col was a promising biomaterial membrane for treating alkali-burned cornea in the early stage, and our attempt may provide a clinically feasible method for the ocular surface reconstruction.

Development of a new indole derivative dry powder for inhalation for the treatment of biofilm-associated lung infections

The aim of this work was to produce an inhalable dry powder formulation of a new anti-biofilm compound (SC38). For this purpose, chitosan was used as a polymeric carrier and l-leucine as a dispersibility enhancer. SC38 was entrapped by spray-drying into previously optimized chitosan microparticles. The final formulation was fully characterized in vitro in terms of particle morphology, particle size and distribution, flowability, aerodynamic properties, anti-biofilm activity and effects on lung cell viability. The SC38-loaded chitosan microparticles exhibited favorable aerodynamic properties with emitted and respirable fractions higher than 80 % and 45 % respectively. The optimized formulation successfully inhibited biofilm formation at microparticle concentrations starting from 20 μg/mL for methicillin-sensitive and 100 μg/mL for methicillin-resistant Staphylococcus aureus and showed a relatively safe profile in lung cells after 72 h exposure. Future in vivo tolerability and efficacy studies are needed to unravel the potential of this novel formulation for the treatment of difficult-to-treat biofilm-mediated lung infections.

Progress in the application of sustained-release drug microspheres in tissue engineering

Sustained-release drug-loaded microspheres provide a long-acting sustained release, with targeted and other effects. There are many types of sustained-release drug microspheres and various preparation methods, and they are easy to operate. For these reasons, they have attracted widespread interest and are widely used in tissue engineering and other fields. In this paper, we provide a systematic review of the application of sustained-release drug microspheres in tissue engineering. First, we introduce this new type of drug delivery system (sustained-release drug carriers), describe the types of sustained-release drug microspheres, and summarize the characteristics of different microspheres. Second, we summarize the preparation methods of sustained-release drug microspheres and summarize the materials required for preparing microspheres. Third, various applications of sustained-release drug microspheres in tissue engineering are summarized. Finally, we summarize the shortcomings and discuss future prospects in the development of sustained-release drug microspheres. The purpose of this paper was to provide a further systematic understanding of the application of sustained-release drug microspheres in tissue engineering for the personnel engaged in related fields and to provide inspiration and new ideas for studies in related fields.

Chitosan-Based Nanomaterial as Immune Adjuvant and Delivery Carrier for Vaccines

With the support of modern biotechnology, vaccine technology continues to iterate. The safety and efficacy of vaccines are some of the most important areas of development in the field. As a natural substance, chitosan is widely used in numerous fields-such as immune stimulation, drug delivery, wound healing, and antibacterial procedures-due to its good biocompatibility, low toxicity, biodegradability, and adhesion. Chitosan-based nanoparticles (NPs) have attracted extensive attention with respect to vaccine adjuvants and delivery systems due to their excellent properties, which can effectively enhance immune responses. Here, we list the classifications and mechanisms of action of vaccine adjuvants. At the same time, the preparation methods of chitosan, its NPs, and their mechanism of action in the delivery system are introduced. The extensive applications of chitosan and its NPs in protein vaccines and nucleic acid vaccines are also introduced. This paper reviewed the latest research progress of chitosan-based NPs in vaccine adjuvant and drug delivery systems.

Theophylline-Loaded Pectin/Chitosan Hydrochloride Submicron Particles Prepared by Spray Drying with a Continuous Feeding Ultrasonic Atomizer

Pectin/chitosan hydrochloride (CHC) particles containing theophylline were prepared by a spray-drying apparatus coupled with a continuous feeding ultrasonic atomizer and a heating column. The formation of the submicron particles was investigated at various compositions of pectin solutions added with a chitosan hydrochloride or calcium chloride solution as a crosslinking agent. Scanning electron microscopic (SEM) images showed the pectin/chitosan hydrochloride particles had spherical and smooth surfaces. Depending on the feeding concentrations, the produced particles had diameters in the range of 300 to 800 nm with a narrow size distribution. Furthermore, the theophylline (TH)-loaded pectin/CHC particles were also prepared by the same apparatus. The TH release from the submicron particles in phosphate-buffered saline at 37 °C was monitored in real-time by a UV-Visible spectrophotometer. The Ritger-Peppas model could well describe the TH release profiles. All the diffusional exponents (n) of the release systems were greater than 0.7; thus, the transport mechanism was not a simple Fickian diffusion. Particularly, the n value was 1.14 for the TH-loaded particles at a pectin/CHC weight ratio of 5/2, which was very close to the zero-order drug delivery (n = 1). Therefore, the constant drug-release rate could be achieved by using the spray-dried pectin/CHC particles as the drug carrier.

Crabs Marine Waste-A Valuable Source of Chitosan: Tuning Chitosan Properties by Chitin Extraction Optimization

Chitin extraction from crab shells was studied experimentally and optimized aiming to obtain chitosan with predefined deacetylation degree and molecular mass. To find out the optimum operating conditions that ensure the obtaining of a chitosan with highest deacetylation degree and specific molecular mass four parameters were varied: the concentration of NaOH and the temperature for deproteinization step, respectively HCl concentration and the number of acidic treatments for the demineralization stage. The experiment was carried on following Taguchi orthogonal array L9, and the best combination of factors was found using the desirability function approach. The optimization results showed that 5% NaOH concentration and low temperatures lead to a chitosan with high deacetylation degree. High molecular mass chitosan is obtained when a single step acidic treatment is used, while a chitosan with low molar mass is obtained for multiple acid contacts and higher HCl concentration.

Zingiber officinale essential oil-loaded chitosan-tripolyphosphate nanoparticles: Fabrication, characterization and in-vitro antioxidant and antibacterial activities

Zingiber officinale essential oil (ZEO) was encapsulated in chitosan nanoparticles at different concentrations using the emulsion-ionic gelation technique and its antioxidant and antibacterial effects were investigated. The results indicated that ZEO level had a significant effect on encapsulation efficiency (EE), loading capacity (LC), particle size and zeta potential. The value obtained for EE, LC, mean particle size and zeta potential were 49.11%-68.32%, 21.16%-27.54%, 198.13-318.26 nm and +21.31-43.57 mV, respectively. According to scanning electron micrographs, the nanoparticles had a spherical shape with some invaginations due to the drying process. The presence of essential oil within the chitosan nanoparticles was confirmed by Fourier transform infrared (FTIR) spectroscopy. In vitro release studies in simulated gastrointestinal fluid (SGF) and simulated intestinal fluid (SIF) indicated an initial burst effect followed by slow release with higher release rate in acidic medium of SGF. ZEO-loaded nanoparticles showed DPPH radical scavenging activity of 20%-61% which increased by raising the ZEO level. Moreover, results of antibacterial activity revealed that Staphylococcus aureus (with inhibition zones of 19-35.19 mm2) and Salmonella typhimurium (with inhibition zones of 9.78-17.48 mm2) were the most sensitive and resistant bacteria to ZEO, respectively. Overall, chitosan nanoparticles can be considered as suitable vehicles for ZEO and improve its stability and solubility.

Changes in Number and Antibacterial Activity of Silver Nanoparticles on the Surface of Suture Materials during Cyclic Freezing

This article presents the results of the 10-fold cyclic freezing (−37.0 °C) and thawing (0.0 °C) effect on the number and size range of silver nanoparticles (AgNPs). AgNPs were obtained by the cavitation-diffusion photochemical reduction method and their sorption on the fiber surface of various suture materials, perlon, silk, and catgut, was studied. The distribution of nanoparticles of different diameters before and after the application of the cyclic freezing/thawing processes for each type of fibers studied was determined using electron microscopy. In general, the present study demonstrates the effectiveness of using the technique of 10-fold cyclic freezing. It is applicable to increase the absolute amount of AgNPs on the surface of the suture material with a simultaneous decrease in the size dispersion. It was also found that the application of the developed technique leads to the overwhelming predominance of nanoparticles with 1 to 15 nm diameter on all the investigated fibers. In addition, it was shown that after the application of the freeze/thaw method, the antibacterial activity of silk and catgut suture materials with AgNPs was significantly higher than before their treatment by cyclic freezing.

EGDMA- and TRIM-Based Microparticles Imprinted with 5-Fluorouracil for Prolonged Drug Delivery

Imprinted materials possess designed cavities capable of forming selective interactions with molecules used in the imprinting process. In this work, we report the synthesis of 5-fluorouracil (5-FU)-imprinted microparticles and their application in prolonged drug delivery. The materials were synthesized using either ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TRIM) cross-linkers. For both types of polymers, methacrylic acid was used as a functional monomer, whereas 2-hydroxyethyl methacrylate was applied to increase the final materials’ hydrophilicity. Adsorption isotherms and adsorption kinetics were investigated to characterize the interactions that occur between the materials and 5-FU. The microparticles synthesized using the TRIM cross-linker showed higher adsorption properties towards 5-FU than those with EGDMA. The release kinetics was highly dependent upon the cross-linker and pH of the release medium. The highest cumulative release was obtained for TRIM-based microparticles at pH 7.4. The IC₅₀ values proved that 5-FU-loaded TRIM-based microparticles possess cytotoxic activity against HeLa cell lines similar to pure 5-FU, whereas their toxicity towards normal HDF cell lines was ca. three times lower than for 5-FU.

Emerging nanotechnology role in the development of innovative solutions against COVID-19 pandemic

The COVID-19 outbreak is creating severe impressions on all facets of the global community. Despite strong measures worldwide to try and re-achieve normalcy, the ability of SARS-CoV-2 to survive sturdy ecological settings may contribute to its rapid spread. Scientists from different aspects of life are working together to develop effective treatment strategies against SARS-CoV-2. Apart from using clinical devices for patient recovery, the key focus is on developing antiviral drugs and vaccines. Given the physical size of the SARS-CoV-2 pathogen and with the vaccine delivery platform currently undergoing clinical trials, the link between nanotechnology is clear, and previous antiviral research using nanomaterials confirms this link. Nanotechnology based products can effectively suppress various pathogens, including viruses, regardless of drug resistance, biological structure, or physiology. Thus, nanotechnology is opening up new dimensions for developing new strategies for diagnosing, preventing, treating COVID-19 and other viral ailments. This article describes the application of nanotechnology against the COVID-19 virus in terms of therapeutic purposes and vaccine development through the invention of nanomaterial based substances such as sanitizers (handwashing agents and surface disinfectants), masks and gowns, amongst other personal protective equipment, diagnostic tools, and nanocarrier systems, as well as the drawbacks and challenges of nanotechnology that need to be addressed.

PLGA-based biodegradable microspheres in drug delivery: recent advances in research and application

Biodegradable microspheres have been widely used in the field of medicine due to their ability to deliver drug molecules of various properties through multiple pathways and their advantages of low dose and low side effects. Poly (lactic-co-glycolic acid) copolymer (PLGA) is one of the most widely used biodegradable material currently and has good biocompatibility. In application, PLGA with a specific monomer ratio (lactic acid and glycolic acid) can be selected according to the properties of drug molecules and the requirements of the drug release rate. PLGA-based biodegradable microspheres have been studied in the field of drug delivery, including the delivery of various anticancer drugs, protein or peptide drugs, bacterial or viral DNA, etc. This review describes the basic knowledge and current situation of PLGA biodegradable microspheres and discusses the selection of PLGA polymer materials. Then, the preparation methods of PLGA microspheres are introduced, including emulsification, microfluidic technology, electrospray, and spray drying. Finally, this review summarizes the application of PLGA microspheres in drug delivery and the treatment of pulmonary and ocular-related diseases.

Encapsulation and controlled release of vitamin C in modified cellulose nanocrystal/chitosan nanocapsules

Vitamin C (VC), widely used in food, pharmaceutical and cosmetic products, is susceptible to degradation, and new formulations are necessary to maintain its stability. To address this challenge, VC encapsulation was achieved via electrostatic interaction with glycidyltrimethylammonium chloride (GTMAC)-chitosan (GCh) followed by cross-linking with phosphorylated-cellulose nanocrystals (PCNC) to form VC-GCh-PCNC nanocapsules. The particle size, surface charge, degradation, encapsulation efficiency, cumulative release, free-radical scavenging assay, and antibacterial test were quantified. Additionally, a simulated human gastrointestinal environment was used to assess the efficacy of the encapsulated VC under physiological conditions. Both VC loaded, GCh-PCNC, and GCh-Sodium tripolyphosphate (TPP) nanocapsules were spherical with a diameter of 450 ​± ​8 and 428 ​± ​6 ​nm respectively. VC-GCh-PCNC displayed a higher encapsulation efficiency of 90.3 ​± ​0.42% and a sustained release over 14 days. The release profiles were fitted to the first-order and Higuchi kinetic models with R² values greater than 0.95. VC-GCh-PCNC possessed broad-spectrum antibacterial activity with a minimum inhibition concentration (MIC) of 8–16 ​μg/mL. These results highlight that modified CNC-based nano-formulations can preserve, protect and control the release of active compounds with improved antioxidant and antibacterial properties for food and nutraceutical applications.

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Vitamin C (VC) was encapsulated by modified chitosan and cellulose nanocrystals.

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Phosphorylated cellulose nanocrystal (PCNC) was used as a cross-linking agent.

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The encapsulation efficiency of the prepared VC-GCh-PCNC was 90.3 ​± ​0.42%.

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At 14 days, nanocapsules prepared using PCNC and TPP released 10% and 70% VC respectively.

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GTMAC-chitosan (GCh) and VC contributed antibacterial function to the nanocomplex.

Recent advances in microfluidic-aided chitosan-based multifunctional materials for biomedical applications

Chitosan-based biomaterials has shown great advantages in a broad range of applications, including drug delivery, clinical diagnosis, cell culture and tissue engineering. However, due to the lack of control over the fabrication processes by conventional techniques, the wide application of chitosan-based biomaterials has been hampered. Recently, microfluidics has been demonstrated as one of the most promising platforms to fabricate high-performance chitosan-based multifunctional materials with monodisperse size distribution and accurately controlled morphology and microstructures, which show great promising for biomedical applications. Here, we review recent progress of the fabrication of chitosan-based biomaterials with different structures and integrated functions by microfluidic technology. A comprehensive and in-depth depiction of critical microfluidic formation mechanism and process of various chitosan-based materials are first interpreted, with particular descriptions about the microfluidic-mediated control over the morphology and microstructures. Afterwards, recently emerging representative applications of chitosan-based multifunctional materials in various fields, are systematically summarized. Finally, the conclusions and perspectives on further advancing the microfluidic-aided chitosan-based multifunctional materials toward potential and versatile development for fundamental researches and biomedicine are proposed.

Influence of Chitin Source and Polymorphism on Powder Compression and Compaction: Application in Drug Delivery

The objective of the research reported herein is to compare the compaction properties of three different chitin extracts from the organisms most used in the seafood industry; namely crabs, shrimps and squids. The foregoing is examined in relation to their polymorphic forms as well as compression and compaction behavior. Chitin extracted from crabs and shrimps exhibits the α-polymorphic form whilst chitin extracted from squid pins displays a β-polymorphic form. These polymorphs were characterized using FTIR, X-ray powder diffraction and scanning electron microscopy. Pore diameter and volume differ between the two polymorphic powder forms. The β form is smaller in pore diameter and volume. Scanning electron microscopy of the two polymorphic forms shows clear variation in the arrangement of chitin layers such that the α form appears more condensed due to the anti-parallel arrangement of the polymer chains. True, bulk and tapped densities of these polymorphs and their mixtures indicated poor flowability. Nevertheless, compression and compaction properties obtained by applying Heckle and Kawakita analyses indicated that both polymorphs are able to be compacted with differences in the extent of compaction. Chitin compacts, regardless of their origin, showed a very high crushing strength with very fast dissolution which makes them suitable for use as fast mouth dissolving tablets. Moreover, when different chitin powders are granulated with two model drugs, i.e., metronidazole and spiramycin they yielded high crushing strength and their dissolution profiles were in accordance with compendial requirements. It is concluded that the source of chitin extraction is as important as the polymorphic form when compression and compaction of chitin powders is carried out.

Pharmaceutical nanotechnology: which products are been designed against COVID-19?

The current pandemic COVID-19, caused by the SARS-CoV-2 virus, has been affecting thousands of people worldwide, promoting high numbers of deaths. With this, the world population is going through a process of changing habits, with social distance, improvement of hygiene techniques, to reduce the spread of the SARS-CoV-2 virus and, consequently, reduce the number of hospitalized people in serious condition, as well as the mortality rate. This scenario has been promoting a continuous search for researchers, in the most varied areas, for possible methods of prevention or cure. Specifically, in the field of pharmaceutical nanotechnology, a variety of products are being developed against SARS-CoV-2. Under these circumstances, we propose here an exposition of some of the nanotechnological products (nanoscale between 1 to 1000 nm) currently designed for the detection of the virus, for the prevention and treatment of COVID-19, in addition to equipment for personal protection. We believe that pharmaceutical nanotechnology will be a valuable tool in the disease from the development of products that guarantee our protection against the SARS-CoV-2 virus.

Microencapsulation of Copper(II) Sulfate in Ionically Cross-Linked Chitosan by Spray Drying for the Development of Irreversible Moisture Indicators in Paper Packaging

Copper(II) sulfate-loaded chitosan microparticles were herein prepared using ionic cross-linking with sodium tripolyphosphate (STPP) followed by spray drying. The microencapsulation process was optimal using an inlet temperature of 180 °C, a liquid flow-rate of 290 mL/h, an aspiration rate of 90%, and an atomizing gas flow-rate of 667 nL/h. Chitosan particles containing copper(II) sulfate of approximately 4 µm with a shrunken-type morphology were efficiently attained and, thereafter, fixated on a paper substrate either via cross-linking with STPP or using a chitosan hydrogel. The latter method led to the most promising system since it was performed at milder conditions and the original paper quality was preserved. The developed cellulose substrates were reduced and then exposed to different humidity conditions and characterized using colorimetric measurements in order to ascertain their potential as irreversible indicators for moisture detection. The results showed that the papers coated with the copper(II) sulfate-containing chitosan microparticles were successfully able to detect ambient moisture shown by the color changes of the coatings from dark brown to blue, which can be easily seen with the naked eye. Furthermore, the chitosan microparticles yielded no cytotoxicity in an in vitro cell culture experiment. Therefore, the cellulose substrates herein developed hold great promise in paper packaging as on-package colorimetric indicators for monitoring moisture in real time.

Microencapsulation of Bifidobacterium animalis subsp. lactis BB-12 with mannitol

Bifidobacterium animalis subsp. lactis BB-12 (BB-12) was microencapsulated using co-extrusion technology with chitosan coating and the incorporation of mannitol as prebiotic. Optimization of coating material chitosan concentration (0–0.5% w/v) and mannitol concentration (0–5% w/v) as prebiotic were performed to determine the formulation that produces beads with desired properties. The microencapsulation efficiency (MEE) of free and microencapsulated BB-12 (with and without mannitol) were determined. All forms of BB-12 further subjected to sequential digestion in simulated gastric juice (SGJ, pH 2.0) for 2 hours and simulated intestinal juice (SIJ, pH 7.5) for 3 hours. The results indicated that 0.4% (w/v) of chitosan coating and 3% (w/v) of mannitol were the optimum concentrations to produce microencapsulated BB-12 with the highest MEE of 89.15% and the average bead size of 805 µm. The BB-12 beads produced through co-extrusion were spherical with a smooth surface. Throughout the five hours sequential gastrointestinal digestion, both microencapsulated BB-12 with and without mannitol were able to maintain their viable cell count at least 106 CFU/g at the end of the incubation. The presence of prebiotic mannitol showed a significant protective effect on the microencapsulated BB-12 during gastrointestinal transit.