Chitosan nanoparticles for the linear release of model cationic Peptide

Development, Evaluation, and Molecular Dynamics Study of Ampicillin-Loaded Chitosan-Hyaluronic Acid Films as a Drug Delivery System

Periodontitis is an inflammatory periodontal disease defined by the progressive loss of tissues surrounding the tooth. Ampicillin is an antibiotic for managing and treating specific bacterial infections, including periodontitis. Periodontal pockets occur due to periodontal disease progression and act as a natural reservoir that is easily reachable for the insertion of a delivery system, and the amount of drug to be released has a major role in the efficiency of treatment of the disease. Polyelectrolyte complexes (PECs), particularly those based on chitosan and hyaluronic acid combinations, offer a promising avenue to overcome the challenges associated with drug delivery. These complexes are both biodegradable and biocompatible, making them an optimal choice for enabling targeted drug delivery. This study centers on developing and assessing the structure and dynamic attributes of a drug-PEC system encompassing ampicillin and chitosan-hyaluronic acid components, which represents a targeted drug delivery system to better alleviate the periodontitis. To achieve this goal, we conducted experiments including weight and drug content uniformity, swelling ındex, drug release %, FT-IR and SEM analyses, and atomistic molecular dynamics simulations on the drug PECs loaded with ampicillin with varying amounts of hyaluronic acid. All simulations and the experimental analysis suggested that increased HA amount resulted in an increase in drug release % and swelling index. The simulation outcomes provide insights into the nature of the drug and PEC interactions alongside transport properties such as drug diffusion coefficients. These coefficients offer valuable insights into the molecular behavior of ampicillin-PEC drug delivery systems, particularly in the context of their application in periodontitis treatment.

Trichinella spiralis: A new parasitic target for curcumin nanoformulas in mice models

Trichinosis spiralis is a global disease with significant economic impact. Albendazole is the current-treatment. Yet, the world-widely emerging antimicrobial resistance necessitates search for therapeutic substitutes. Curcumin is a natural compound with abundant therapeutic benefits. This study aimed to evaluate the potential of crude-curcumin, chitosan and for the first time curcumin-nano-emulsion and curcumin-loaded-chitosan-nanoparticles against Trichinella spiralis adults and larvae in acute and chronic trichinosis models. Trichinosis spiralis was induced in 96 Swiss-albino mice. Infected mice were divided into 2 groups. Group I constituted the acute model, where treatment started 2 h after infection for 5 successive days. Group II constituted the chronic model, where treatment started at the 30th day-post-infection and continued for 10 successive days (Refer to graphical abstract). Each group contained 8 subgroups that were designated Ia-Ih and IIa-IIh and included; a; Untreated-control, b; Albendazole-treated (Alb-treated), c; Crude-curcumin-treated (Cur-treated), d; Curcumin-nanoemulsion-treated (Cur-NE-treated), e; Albendazole and crude-curcumin-treated (Alb-Cur-treated), f; Albendazole and curcumin-nanoemulsion-treated (Alb-Cur-NE-treated), g; Chitosan-nanoparticles-treated (CS-NPs-treated) and h; Curcumin-loaded-chitosan-nanoparticles-treated (Cur-CS-NPs-treated). Additionally, six mice constituted control-uninfected group III. The effects of the used compounds on the parasite tegument, in-vivo parasitic load-worm burden, local pathology and MDA concentration in small intestines of acutely-infected and skeletal muscle of chronically-infected mice were studied. Results showed that albendazole was effective, yet, its combination with Cur-NE showed significant potentiation against adult worms and muscle larvae and alleviated the pathology in both models. Cur-CS-NPs exhibited promising results in both models. Crude-curcumin showed encouraging results especially against muscle larvae on long-term use. Treatments effectively reduced parasite load, local MDA level and CD31 expression with anti-inflammatory effect in intestine and muscle sections.

Effectiveness In Vivo and In Vitro of Polymeric Nanoparticles as a Drug Release System in the Treatment of Leishmaniasis

Leishmaniasis is a neglected disease caused by the parasite of the genus Leishmania. Current treatment regimens are obsolete and cause several side effects, promoting poor patient compliance, in addition to the vast majority already having the potential for resistance. Therefore, polymeric nanoparticles emerge as one of the viable alternatives to overcome existing limitations, through passive or active vectorization. This review aims to summarize the latest studies of polymeric nanoparticles as an alternative treatment for leishmaniasis. In the first section, the main pharmacokinetic and pharmacodynamic challenges of current drugs are reported. The second section details how nanoparticles with and without functionalization are efficient in the treatment of leishmaniasis, discussing the characteristics of the polymer in the formulation. In this way, polymeric nanoparticles can improve the physicochemical properties of leishmanicidal drugs, improving solubility and stability, as well as improve the release of these drugs, directly or indirectly reaching monocytes/macrophages. 64.28% drugs were focused on the treatment of visceral leishmaniasis, and 28.57% on cutaneous leishmaniasis. The most chosen polymers in the literature are chitosan (35.71%) and PLGA (35.71%), the others represented 14.30% drugs, with all able to manage the drug release and increase the in vitro and/or in vivo efficacy of the original molecule. However, there are several barriers for these nanoformulations to cross laboratory research and is necessary more in-depth studies about the metabolites and degradation pathways of the polymers used in the formulations and plasma proteomics studies.

Preparation and in vitro characterization of curcumin loaded Chitosan-Hyaluronic acid polyelectrolyte complex based hydrogels

OBJECTIVE

The manuscript aims to prepare and comprehensively characterize curcumin-loaded chitosan-hyaluronic acid polyelectrolyte complex (PEC) hydrogels through in vitro assessments. By elucidating the formulation process, physicochemical attributes, and drug release kinetics, the study contributes to the producing of curcumin loaded new drug delivery system.

SIGNIFICANCE

This approach shows the unique synergy of the chosen polymers with curcumin. The meticulous in vitro analysis of the hydrogels cements their novel attributes, underlining their potential as efficacious and biocompatible curcumin carriers.

METHODS

To configure the optimum formulation variables, viscosity, swelling ratio, porosity, in vitro release, cell viability, and migration rate were determined. In addition, FTIR and SEM analyses were also carried out to define the characteristic of formulations.

RESULTS

Release kinetic determination is essential in estimating the release behavior of formulation in the body. All formulations showed Higuchi release kinetics, indicating that drug release from the semi-solid matrix was diffusion controlled.

CONCLUSION

As a result, in this study, a new formulation was produced based on a simple concept with acceptable quality parameter results promising to be conducted in the industry.

Growth patterns of Pseudomonas aeruginosa in milk fortified with chitosan and selenium nanoparticles during refrigerated storage

Pseudomonas spp are considered a common milk-associated psychotropic bacteria, leading to milk deterioration during storage; therefore, our study aimed to study the distribution of Pseudomonas aeruginosa in raw milk and its associated products then studying the growth behavior of P. aeruginosa in milk after employing chitosan nanoparticles (CsNPs 50, 25, and 15 mg/100ml) and selenium nanoparticles (SeNPs 0.5, 0.3 and 0.1 mg/100ml) as a trial to control the bacterial growth in milk during five days of cooling storage. Our study relies on the ion gelation method and green synthesis for the conversion of chitosan and selenium to nanosized particles respectively, we subsequently confirmed their shape using SEM and TEM. We employing Pseudomonas selective agar medium for monitoring the bacterial growth along the cooling storage. Our findings reported that high prevalence of Pseudomonas spp count in raw milk and kareish cheese and high incidence percent of P. aeruginosa in ice cream and yogurt respectively. Both synthesized nanoparticles exhibited antibacterial activity in a dose-dependent manner. Moreover, CsNPs50 could inhibit the P. aeruginosa survival growth to a mean average of 2.62 ± 1.18 log10cfu/ml in the fifth day of milk cooling storage; also, it was noted that the hexagonal particles SeNPs0.5 could inhibit 2.49 ± 11 log10cfu/ml in comparison to the control P. aeruginosa milk group exhibited growth survival rate 7.24 ± 2.57 log10cfu/ml under the same conditions. In conclusion, we suggest employing chitosan and selenium nanoparticles to improve milk safety and recommend future studies for the fate of nanoparticles in milk.

pH-sensitive biocompatible chitosan/sepiolite-based cross-linked citric acid magnetic nanocarrier for efficient sunitinib release

In this study, the magnetite nanoparticles were immobilized on the sepiolite needles via co-precipitation of iron ions. Then, the resulted magnetic sepiolite (mSep) nanoparticles were coated with chitosan biopolymer (Chito) in the presence of citric acid (CA) to prepare mSep@Chito core-shell drug nanocarriers (NCs). TEM images showed magnetic Fe₃O₄ nanoparticles with small sizes (less than 25 nm) on the sepiolite needles. Sunitinib anticancer drug loading efficiencies were ⁓45 and 83.7 % for the NCs with low and high content of Chito, respectively. The in-vitro drug release results exhibited that the mSep@Chito NCs have a sustained release behavior with high pH-dependent properties. Cytotoxic results (MTT assay) showed that the sunitinib-loaded mSep@Chito2 NC had a significant cytotoxic effect on the MCF-7 cell lines. Also, the in-vitro compatibility of erythrocytes, physiological stability, biodegradability, and antibacterial and antioxidant activities of NCs was evaluated. The results showed that the synthesized NCs had excellent hemocompatibility, good antioxidant properties, and were sufficiently stable and biocompatible. Based on the antibacterial data, the minimal inhibitory concentration (MIC) values for mSep@Chito1, mSep@Chito2, and mSep@Chito3 were obtained as 125, 62.5, and 31.2 μg/mL towards S. aureus, respectively. All in all, the prepared NCs could be potentially used as a pH-triggered system for biomedical applications.

Antimicrobial Peptide Octominin-Encapsulated Chitosan Nanoparticles Enhanced Antifungal and Antibacterial Activities

Antimicrobial peptides (AMPs) have become a key solution for controlling multi-drug-resistant (MDR) pathogens, and the nanoencapsulation of AMPs has been used as a strategy to overcome challenges, such as poor stability, adverse interactions, and toxicity. In previous studies, we have shown the potent antimicrobial activity of Octominin against Candida albicans and Acinetobacter baumannii. This study is focused on the nanoencapsulation of Octominin with chitosan (CS) and carboxymethyl chitosan (CMC) as a drug delivery system using the ionotropic gelation technique. Octominin-encapsulated CS nanoparticles (Octominin-CNPs) had an average diameter and zeta potential of 372.80 ± 2.31 nm and +51.23 ± 0.38 mV, respectively, while encapsulation efficiency and loading capacity were 96.49 and 40.20%, respectively. Furthermore, Octominin-CNPs showed an initial rapid and later sustained biphasic release profile, and up to 88.26 ± 3.26% of the total Octominin release until 96 h. Transmission electron microscopy data showed the irregular shape of the Octominin-CNPs with aggregations. In vitro and in vivo toxicity of Octominin-CNPs was significantly lower than the Octominin at higher concentrations. The antifungal and antibacterial activities of Octominin-CNPs were slightly higher than those of Octominin in both the time-kill kinetic and microbial viability assays against C. albicans and A. baumannii, respectively. Mode of action assessments of Octominin-CNPs revealed that morphological alterations, cell membrane permeability alterations, and reactive oxygen species generation were slightly higher than those of Octominin at the tested concentrations against both C. albicans and A. baumannii. In antibiofilm activity assays, Octominin-CNPs showed slightly higher biofilm inhibition and biofilm eradication activities compared to that of Octominin. In conclusion, Octominin was successfully encapsulated into CS, and Octominin-CNPs showed lower toxicity and greater antimicrobial activity against C. albicans and A. baumannii compared to Octominin.

Targeting dendritic cells with TLR-2 ligand-coated nanoparticles loaded with Mycobacterium tuberculosis epitope induce antituberculosis immunity

Novel vaccination strategies are crucial to efficiently control tuberculosis, as proposed by the World Health Organization under its flagship program "End TB Strategy." However, the emergence of drug-resistant strains of Mycobacterium tuberculosis (Mtb), particularly in those coinfected with HIV-AIDS, constitutes a major impediment to achieving this goal. We report here a novel vaccination strategy that involves synthesizing a formulation of an immunodominant peptide derived from the Acr1 protein of Mtb. This nanoformulation in addition displayed on the surface a toll-like receptor-2 ligand to offer to target dendritic cells (DCs). Our results showed an efficient uptake of such a concoction by DCs in a predominantly toll-like receptor-2-dependent pathway. These DCs produced elevated levels of nitric oxide, proinflammatory cytokines interleukin-6, interleukin-12, and tumor necrosis factor-α, and upregulated the surface expression of major histocompatibility complex class II molecules as well as costimulatory molecules such as CD80 and CD86. Animals injected with such a vaccine mounted a significantly higher response of effector and memory Th1 cells and Th17 cells. Furthermore, we noticed a reduction in the bacterial load in the lungs of animals challenged with aerosolized live Mtb. Therefore, our findings indicated that the described vaccine triggered protective anti-Mtb immunity to control the tuberculosis infection.

New Formulation to Accelerate the Degradation of Pesticide Residues: Composite Nanoparticles of Imidacloprid and 24-Epibrassinolide

Pest control effectiveness and residues of pesticides are contradictory concerns in agriculture and environmental conservation. On the premise of not affecting the insecticidal effect, the pesticide residues in the later stage should be degraded as fast as possible. In the present study, composite nanoparticles in a double-layer structure, consisting of imidacloprid (IMI) in the outer layer and plant hormone 24-epibrassinolide (24-EBL) in the inner layer, were prepared by the W/O/W solvent evaporation method using Eudragit RL/RS and polyhydroxyalkanoate as wall materials. The release of IMI in the outer layer was faster and reached the maximum within 24 h, while the release of 24-EBL in the inner layer was slower and reached the maximum within 96 h. The contact angle of the composite nanoparticles was half that of the 5% IMI emulsifiable concentrate (EC), and the deposition of composite nanoparticles on rice was twice that of 5% IMI EC, which increased the pesticide utilization efficiency. Compared with the common pesticide, 5% IMI EC, the insecticidal effect of the composite nanoparticles was stronger than that of planthoppers, with a much lower final residue amount on rice after 21 days. The composite nanoparticles prepared in this study to achieve sustained release of pesticides and, meanwhile, accelerate the degradation of pesticide residues have a strong application potential in agriculture for controlling pests and promoting crop growth.

Nanoencapsulated Lippia rotundifolia antimicrobial peptide: synthesis, characterization, antimicrobial activity, and cytotoxicity evaluations

Antimicrobial peptides (AMP) are promising novel antibiotics but exhibit low stability and can be toxic. The AMP encapsulation can be used to protect the drug and control its release rates. The Lr-AMP1f encapsulated into chitosan nanoparticle (NP) by ionic gelation method reached 90% efficiency. The results indicated that the hydrodynamic particle size of NPs increased from 196.1 ± 3.14 nm (free NP) to 228.1 ± 12.22 nm (nanoencapsulated Lr-AMP1f), while the atomic force microscope showed the spherical shape. The Zeta potential of the nanoencapsulated Lr-AMP1f was high (+ 35 mV). These AMP-loaded NPs exhibited stability for up to 21 days of storage. The minimum inhibitory concentration (MIC) of free Lr-AMP1f was 8 µg/mL for E. coli and S. epidermidis. However, the nanoencapsulated Lr-AMP1f produced a bacteriostatic effect against both bacteria at 8 µg/mL. The MIC of nanoencapsulated Lr-AMP1f was 16 µg/mL for E. coli and 32 for S. epidermidis. Nanoencapsulated Lr-AMP1f was nontoxic to HEK293 cells. Promisingly, chitosan NP can be used as a vehicle for the antibacterial application of new AMP (Lr-AMP1f).

Characterization, Bioactivity and Application of Chitosan-Based Nanoparticles in a Food Emulsion Model

In this study, chitosan nanoparticles (CNPs) were prepared by the ionic gelation technique with tripolyphosphate (TPP), and the effect of CNP composition and physicochemical characteristics were evaluated. After the synthesis optimization, CNPs were used as carriers for a fish protein hydrolysate (FPH) with bioactive properties (CNPH). The physicochemical characteristics, antioxidant capacity and antimicrobial, antihypertensive and emulsifier properties of unloaded and loaded CNPs in a food system model were studied. CNPH showed a uniform particle distribution, size ~200 nm, high stability (zeta potential around 30 mV), radical scavenging activity and increased antimicrobial activity against Staphylococcus aureus, Shigella sonnei and Aeromonas hydrophila. Additionally, CNPH showed an angiotensin I-converting enzyme (ACE)-inhibitory activity of 63.6% and, when added to a food emulsion model, this system containing CNPs, with or without FHP, exhibited improved food emulsion stability. Thus, CNPs were able to carry the FPH while maintaining their bioactive properties and can be an alternative to the delivery of bioactive peptides with potential as an emulsion stabilizer for food applications.

Nanoparticles Based on Quaternary Ammonium Chitosan-methyl-β-cyclodextrin Conjugate for the Neuropeptide Dalargin Delivery to the Central Nervous System: An In Vitro Study

Peptide oral administration is a hard goal to reach, especially if the brain is the target site. The purpose of the present study was to set up a vehicle apt to promote oral absorption of the neuropeptide dalargin (DAL), allowing it to cross the intestinal mucosal barrier, resist enzymatic degradation, and transport drugs to the brain after crossing the blood–brain barrier. Therefore, a chitosan quaternary ammonium derivative was synthesized and conjugated with methyl-β-cyclodextrin to prepare DAL-medicated nanoparticles (DAL-NP). DAL-NP particle size was 227.7 nm, zeta potential +8.60 mV, encapsulation efficiency 89%. DAL-NP protected DAL from degradation by chymotrypsin or pancreatin and tripled DAL degradation time compared to non-encapsulated DAL. Use of DAL-NP was safe for either Caco-2 or bEnd.3 cells, with the latter selected as a blood–brain barrier model. DAL-NP could also cross either the Caco-2 or bEnd.3 monolayer by the transepithelial route. The results suggest a potential DAL-NP ability to transport to the brain a DAL dose fraction administered orally, although in vivo experiments will be needed to confirm the present data obtained in vitro.

Antibacterial, Antibiofilm, and Antiadhesive Properties of Different Quaternized Chitosan Derivatives

In the era of antimicrobial resistance, the identification of new antimicrobials is a research priority at the global level. In this regard, the attention towards functional antimicrobial polymers, with biomedical/pharmaceutical grade, and exerting anti-infective properties has recently grown. The aim of this study was to evaluate the antibacterial, antibiofilm, and antiadhesive properties of a number of quaternized chitosan derivatives that have displayed significant muco-adhesive properties and wound healing promotion features in previous studies. Low (QAL) and high (QAH) molecular weight quaternized chitosan derivatives were synthetized and further modified with thiol moieties or pendant cyclodextrin, and their antibacterial activity evaluated as minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC). The ability of the derivatives to prevent biofilm formation was assessed by crystal violet staining. Both QAL and QAH derivatives exerted a bactericidal and/or inhibitory activity on the growth of P. aeruginosa and S. epidermidis. The same compounds also showed marked dose-dependent anti-biofilm activity. Furthermore, the high molecular weight derivative (QAH) was used to functionalize titanium plates. The successful functionalization, demonstrated by electron microscopy, was able to partially inhibit the adhesion of S. epidermidis at 6 h of incubation. The shown ability of the chitosan derivatives tested to both inhibit bacterial growth and/or biofilm formation of clinically relevant bacterial species reveals their potential as multifunctional molecules against bacterial infections.

Exploiting chitosan and gold nanoparticles for antimycobacterial activity of in silico identified antimicrobial motif of human neutrophil peptide-1

The upsurge of drug resistant tuberculosis is major health threat globally. To counteract, antimicrobial peptides are being explored as possible alternatives. However, certain limitations of peptide-based drugs such as potential toxicity, high cost and relatively low stability need to be addressed to enhance their clinical applicability. Use of computer predicted short active motifs of AMPs along with nanotechnology could not only overcome the limitations of AMPs but also potentiate their antimicrobial activity. Therefore, present study was proposed to in silico identify short antimicrobial motif (Pep-H) of human neutrophil peptide-1 (HNP-1) and explore its antimycobacterial activity in free form and using nanoparticles-based delivery systems. Based on colony forming unit analysis, motif Pep-H led to killing of more than 90% M. tb in vitro at 10 μg/ml, whereas, similar activity against intracellularly growing M. tb was observed at 5 μg/ml only. Thereafter, chitosan (244 nm) and gold nanoparticles (20 nm) were prepared for Pep-H with both the formulations showing minimal effects on the viability of human monocyte derived macrophages (MDMs) and RBC integrity. The antimycobacterial activity of Pep-H against intracellular mycobacteria was enhanced in both the nanoformulations as evident by significant reduction in CFU (>90%) at 5-10 times lower concentrations than that observed for free Pep-H. Thus, Pep-H is an effective antimycobacterial motif of HNP-1 and its activity is further enhanced by chitosan and gold nanoformulations.

The antimicrobial peptide SAAP-148 combats drug-resistant bacteria and biofilms

Development of novel antimicrobial agents is a top priority in the fight against multidrug-resistant (MDR) and persistent bacteria. We developed a panel of synthetic antimicrobial and antibiofilm peptides (SAAPs) with enhanced antimicrobial activities compared to the parent peptide, human antimicrobial peptide LL-37. Our lead peptide SAAP-148 was more efficient in killing bacteria under physiological conditions in vitro than many known preclinical- and clinical-phase antimicrobial peptides. SAAP-148 killed MDR pathogens without inducing resistance, prevented biofilm formation, and eliminated established biofilms and persister cells. A single 4-hour treatment with hypromellose ointment containing SAAP-148 completely eradicated acute and established, biofilm-associated infections with methicillin-resistant Staphylococcus aureus and MDR Acinetobacter baumannii from wounded ex vivo human skin and murine skin in vivo. Together, these data demonstrate that SAAP-148 is a promising drug candidate in the battle against antibiotic-resistant bacteria that pose a great threat to human health.

Cellular responses of hyaluronic acid-coated chitosan nanoparticles

In recent years, nanotechnology has been proven to offer promising biomedical applications for in vivo diagnostics and drug delivery, stressing the importance of thoroughly investigating the biocompatibility of potentially translatable nanoparticles (NPs). Herein, we report the cellular responses of uncoated chitosan NPs (CS NPs) and hyaluronic acid-coated chitosan NPs (HA-CS NPs) when introduced into Chinese hamster ovary cells (CHO-K1) in a dose-dependent manner (2.5, 0.25, 0.025, 0.0025, and 0.00025 mg mL-1) at two time points (24 and 48 h). MTS assay, cell proliferation, showed a decrease in the viability of cells when treated with 0.25 and 2.5 mg mL-1 CS NPs. When exposed to high doses of CS NPs, the lactate dehydrogenase (LDH) enzyme started to leak out of the cells and the cellular levels of mitochondrial potentials were significantly reduced accompanied by a high production of intracellular reactive oxygen species (ROS). Our study provides molecular evidence of the biocompatibility offered by HA-CS NPs, through ROS scavenging capabilities rescuing cells from the oxidative stress, showing no observed cellular stress and thereby revealing the promising effect of anionic hyaluronic acid to significantly reduce the cytotoxicity of CS NPs. Our findings are important to accelerate the translation and utilization of HA-CS NPs in drug delivery, demonstrating the pronounced effect of surface modifications on modulating the biological responses.

A water-soluble, mucoadhesive quaternary ammonium chitosan-methyl-β-cyclodextrin conjugate forming inclusion complexes with dexamethasone

The ocular bioavailability of lipophilic drugs, such as dexamethasone, depends on both drug water solubility and mucoadhesion/permeation. Cyclodextrins and chitosan are frequently employed to either improve drug solubility or prolong drug contact onto mucosae, respectively. Although the covalent conjugation of cyclodextrin and chitosan brings to mucoadhesive drug complexes, their water solubility is restricted to acidic pHs. This paper describes a straightforward grafting of methyl-β-cyclodextrin (MCD) on quaternary ammonium chitosan (QA-Ch60), mediated by hexamethylene diisocyanate. The resulting product is a water-soluble chitosan derivative, having a 10-atom long spacer between the quaternized chitosan and the cyclodextrin. The derivative is capable of complexing the model drug dexamethasone and stable complexes were also observed for the lyophilized products. Furthermore, the conjugate preserves the mucoadhesive properties typical of quaternized chitosan and its safety as solubilizing excipient for ophthalmic applications was preliminary assessed by in vitro cytotoxicity evaluations. Taken as a whole, the observed features appear promising for future processing of the developed product into 3D solid forms, such as controlled drug delivery systems, films or drug eluting medical devices.

Development of novel ultrashort antimicrobial peptide nanoparticles with potent antimicrobial and antibiofilm activities against multidrug-resistant bacteria

Conventional antibiotics are facing strong microbial resistance that has recently reached critical levels. This situation is leading to significantly reduced therapeutic potential of a huge proportion of antimicrobial agents currently used in clinical settings. Antimicrobial peptides (AMPs) could provide the medical community with an alternative strategy to traditional antibiotics for combating microbial resistance. However, the development of AMPs into clinically useful antibiotics is hampered by their relatively low stability, toxicity, and high manufacturing costs. In this study, a novel in-house-designed potent ultrashort AMP named RBRBR was encapsulated into chitosan-based nanoparticles (CS-NPs) based on the ionotropic gelation method. The encapsulation efficacy reported for RBRBR into CS-NPs was 51.33%, with a loading capacity of 10.17%. The release kinetics of RBRBR from the nanocarrier exhibited slow release followed by progressive linear release for 14 days. The antibacterial kinetics of RBRBR-CS-NPs was tested against four strains of Staphylococcus aureus for 4 days, and the developed RBRBR-CS-NPs exhibited a 3-log decrease in the number of colonies when compared to CS-NP and a 5-log decrease when compared to control bacteria. The encapsulated peptide NP formulation managed to limit the toxicity of the free peptide against both mammalian cells and human erythrocytes. Additionally, the peptide NPs demonstrated up to 98% inhibition of biofilm formation when tested against biofilm-forming bacteria. Loading RBRBR into CS-NPs could represent an innovative approach to develop delivery systems based on NP technology for achieving potent antimicrobial effects against multidrug-resistant and biofilm-forming bacteria, with negligible systemic toxicity and reduced synthetic costs, thereby overcoming the obstructions to clinical development of AMPs.

Preparation of endostatin-loaded chitosan nanoparticles and evaluation of the antitumor effect of such nanoparticles on the Lewis lung cancer model

The purpose of this study was to prepare ES-loaded chitosan nanoparticles (ES-NPs) and evaluate the antitumor effect of these particles on the Lewis lung cancer model. ES-NPs were prepared by a simple ionic cross-linking method. The characterization of the ES-NPs, including size distribution, zeta potential, loading efficiency and encapsulation efficiency (EE), was performed. An in vitro release test was also used to determine the release behavior of the ES-NPs. Cell viability and cell migration were assayed to detect the in vitro antiangiogenic effect of ES-NPs. In order to clarify the antitumor effect of ES-NPs in vivo, the Lewis lung cancer model was used. ES-NPs were successfully synthesized and shown to have a suitable size distribution and high EE. The nanoparticles were spherical and homogeneous in shape and exhibited an ideal releasing profile in vitro. Moreover, ES-NPs significantly inhibited the proliferation and migration of human umbilical vascular endothelial cells (HUVECs). The in vivo antiangiogenic activity was evaluated by ELISA and immunohistochemistry analyses, which revealed that ES-NPs had a stronger antiangiogenic effect for reinforced anticancer activity. Indeed, even the treatment cycle in which ES-NPs were injected every seven days, showed stronger antitumor effect than the free ES injected for 14 consecutive days. Our study confirmed that the CS nanoparticle is a feasible carrier for endostatin to be used in the treatment of lung cancer.

Nanostructures for delivery of natural antimicrobials in food

Natural antimicrobial compounds are a topic of utmost interest in food science due to the increased demand for safe and high-quality foods with minimal processing. The use of nanostructures is an interesting alternative to protect and delivery antimicrobials in food, also providing controlled release of natural compounds such as bacteriocins and antimicrobial proteins, and also for delivery of plant derived antimicrobials. A diversity of nanostructures are capable of trapping natural antimicrobials maintaining the stability of substances that are frequently sensitive to food processing and storage conditions. This article provides an overview on natural antimicrobials incorporated in nanostructures, showing an effective antimicrobial activity on a diversity of food spoilage and pathogenic microorganisms.

Hybrid luminescent porous silicon for efficient drug loading and release

In recent decades, biocompatible and light emitting porous silicon (pSi) showed the possibility for use in biomedical applications.

Nanocarrier fabrication and macromolecule drug delivery: challenges and opportunities

Macromolecules (proteins/peptides) have the potential for the development of new therapeutics. Due to their specific mechanism of action, macromolecules can be administered at relatively low doses compared with small-molecule drugs. Unfortunately, the therapeutic potential and clinical application of macromolecules is hampered by various obstacles including their large size, short in vivo half-life, phagocytic clearance, poor membrane permeability and structural instability. These challenges have encouraged researchers to develop novel strategies for effective delivery of macromolecules. In this review, various routes of macromolecule administration (invasive/noninvasive) are discussed. The advantages/limitations of novel delivery systems and the potential role of nanotechnology for the delivery of macromolecules are elaborated. In addition, fabrication approaches to make nanoformulations in different shapes and sizes are also summarized.

Perspectives on polymeric nanostructures for the therapeutic application of antimicrobial peptides

Antimicrobial peptides (AMPs) are a class of promising anti-infective molecules but their therapeutic application is opposed by their poor bioavailability, susceptibility to protease degradation and potential toxicity. The advancement of nanoformulation technologies offers encouraging perspectives for the development of novel therapeutic strategies based on AMPs to treat antibiotic resistant microbial infections. Additionally, the use of polymers endowed per-se with antibacterial properties, stands out as an innovative approach for the development of a new generation of drug delivery systems in which an enhanced antimicrobial action could be obtained by the synergic combination of bioactive polymer matrices and drugs. Herein, the latest AMPs drug delivery research is discussed.

Antimicrobial peptides: Possible anti-infective agents

Multidrug-resistant bacterial, fungal, viral, and parasitic infections are major health threats. The Infectious Diseases Society of America has expressed concern on the decrease of pharmaceutical companies working on antibiotic research and development. However, small companies, along with academic research institutes, are stepping forward to develop novel therapeutic methods to overcome the present healthcare situation. Among the leading alternatives to current drugs are antimicrobial peptides (AMPs), which are abundantly distributed in nature. AMPs exhibit broad-spectrum activity against a wide variety of bacteria, fungi, viruses, and parasites, and even cancerous cells. They also show potential immunomodulatory properties, and are highly responsive to infectious agents and innate immuno-stimulatory molecules. In recent years, many AMPs have undergone or are undergoing clinical development, and a few are commercially available for topical and other applications. In this review, we outline selected anion and cationic AMPs which are at various stages of development, from preliminary analysis to clinical drug development. Moreover, we also consider current production methods and delivery tools for AMPs, which must be improved for the effective use of these agents.

Chitosan nanoparticles loaded with the antimicrobial peptide temporin B exert a long-term antibacterial activity in vitro against clinical isolates of Staphylococcus epidermidis

Nowadays, the alarming rise in multidrug-resistant microorganisms urgently demands for suitable alternatives to current antibiotics. In this regard, antimicrobial peptides (AMPs) have received growing interest due to their broad spectrum of activities, potent antimicrobial properties, unique mechanisms of action, and low tendency to induce resistance. However, their pharmaceutical development is hampered by potential toxicity, relatively low stability and manufacturing costs. In the present study, we tested the hypothesis that the encapsulation of the frog-skin derived AMP temporin B (TB) into chitosan nanoparticles (CS-NPs) could increase peptide's antibacterial activity, while reducing its toxic potential. TB-loaded CS-NPs with good dimensional features were prepared, based on the ionotropic gelation between CS and sodium tripolyphosphate. The encapsulation efficiency of TB in the formulation was up to 75%. Release kinetic studies highlighted a linear release of the peptide from the nanocarrier, in the adopted experimental conditions. Interestingly, the encapsulation of TB in CS-NPs demonstrated to reduce significantly the peptide's cytotoxicity against mammalian cells. Additionally, the nanocarrier evidenced a sustained antibacterial action against various strains of Staphylococcus epidermidis for at least 4 days, with up to 4-log reduction in the number of viable bacteria compared to plain CS-NPs at the end of the observational period. Of note, the antimicrobial evaluation tests demonstrated that while the intrinsic antimicrobial activity of CS ensured a "burst" effect, the gradual release of TB further reduced the viable bacterial count, preventing the regrowth of the residual cells and ensuring a long-lasting antibacterial effect. The developed nanocarrier is eligible for the administration of several AMPs of therapeutic interest with physical-chemical characteristics analog to those of TB.

Insights into the antimicrobial properties of hepcidins: advantages and drawbacks as potential therapeutic agents

The increasing frequency of multi-drug resistant microorganisms has driven research into alternative therapeutic strategies. In this respect, natural antimicrobial peptides (AMPs) hold much promise as candidates for the development of novel antibiotics. However, AMPs have some intrinsic drawbacks, such as partial degradation by host proteases or inhibition by host body fluid composition, potential toxicity, and high production costs. This review focuses on the hepcidins, which are peptides produced by the human liver with a known role in iron homeostasis, as well by numerous other organisms (including fish, reptiles, other mammals), and their potential as antibacterial and antifungal agents. Interestingly, the antimicrobial properties of human hepcidins are enhanced at acidic pH, rendering these peptides appealing for the design of new drugs targeting infections that occur in body areas with acidic physiological pH. This review not only considers current research on the direct killing activity of these peptides, but evaluates the potential application of these molecules as coating agents preventing biofilm formation and critically assesses technical obstacles preventing their therapeutic application.