Enhanced antibacterial effect of ceftriaxone sodium-loaded chitosan nanoparticles against intracellular Salmonella typhimurium

Efficacy of Gentamicin-Loaded Chitosan Nanoparticles Against Staphylococcus aureus Internalized in Osteoblasts

Staphylococcus aureus, the principal causative agent of osteomyelitis, can be internalized by osteoblasts and thereby escape from immune phagocytes and many kinds of antibiotics. To deliver antibiotics into osteoblasts to kill S. aureus in the intracellular environment, we developed gentamicin-loaded chitosan nanoparticles and evaluated their intracellular bactericidal effect. We found decreased numbers of S. aureus cells in infected osteoblasts treated with gentamicin-loaded chitosan nanoparticles. The cytotoxicity of the nanoparticles was evaluated by CCK-8 assay. There was no significant viability decrease at all tested concentrations. In conclusion, our results provide evidence for the potential use of gentamicin-loaded chitosan nanoparticles to enhance the delivery of gentamicin into cells and for their antibacterial effect against internalized S. aureus in the intracellular environment of osteoblasts.

Evaluation of the Potential of Chitosan Nanoparticles as a Delivery Vehicle for Gentamicin for the Treatment of Osteomyelitis

Chitosan nanoparticle delivery systems have the potential for enhancing bone healing and addressing osteomyelitis. The objective was to deliver antimicrobial agents capable of preventing or treating osteomyelitis. Each formulation was optimized to achieve desired characteristics in terms of size (ranging from 100 to 400 nm), PDI (less than 0.5), zeta potential (typically negative), and in vitro release profiles for gentamicin. Entrapment percentages varied with gentamicin ranging from 10% to 65%. The chitosan nanoparticles exhibited substantial antimicrobial efficacy, particularly against P. aeruginosa and MRSA, with zones of inhibition ranging from 13 to 24 mm and a complete reduction in colony forming units observed between 3 and 24 h. These chitosan nanoparticle formulations loaded with antimicrobials hold promise for addressing orthopedic complications.

Emphasis on Nanostructured Lipid Carriers in the Ocular Delivery of Antibiotics

BACKGROUND

Drug distribution to the eye is still tricky because of the eye's intricate structure. Systemic delivery, as opposed to more traditional methods like eye drops and ointments, is more effective but higher doses can be harmful.

OBJECTIVE

The use of solid lipid nanoparticles (SLNPs) as a method of drug delivery has been the subject of research since the 1990s. Since SLNPs are derived from naturally occurring lipids, they pose no health risks to the user. To raise the eye's absorption of hydrophilic and lipophilic drugs, SLNs can promote corneal absorption and improve the ocular bioavailability of SLNPs.

METHODS

To address problems related to ocular drug delivery, many forms of nano formulation were developed. Some of the methods developed are, emulsification and ultra-sonication, high-speed stirring and ultra-sonication, thin layer hydration, adapted melt-emulsification, and ultrasonication techniques, hot o/w micro-emulsion techniques, etc. Results: Nanostructured lipid carriers are described in this review in terms of their ocular penetration mechanism, structural characteristic, manufacturing process, characterization, and advantages over other nanocarriers.

CONCLUSION

Recent developments in ocular formulations with nanostructured bases, such as surfacemodified attempts have been made to increase ocular bioavailability in both the anterior and posterior chambers by incorporating cationic chemicals into a wide variety of polymeric systems.

Co-administration of amoxicillin-loaded chitosan nanoparticles and inulin: A novel strategy for mitigating antibiotic resistance and preserving microbiota balance in Helicobacter pylori treatment

Helicobacter pylori (H. pylori) is a causative agent of various gastrointestinal diseases and eradication mainly relies on antibiotic treatment, with (AMX) being a key component. However, rising antibiotic resistance in H. pylori necessitates the use of antibiotics combination therapy, often disrupting gut microbiota equilibrium leading to further health complications. This study investigates a novel strategy utilizing AMX-loaded chitosan nanoparticles (AMX-CS NPs), co-administered with prebiotic inulin to counteract H. pylori infection while preserving microbiota health. Following microbroth dilution method, AMX displayed efficacy against H. pylori, with a MIC50 of 48.34 ± 3.3 ng/mL, albeit with a detrimental impact on Lactobacillus casei (L. casei). The co-administration of inulin (500 μg/mL) with AMX restored L. casei viability while retaining the lethal effect on H. pylori. Encapsulation of AMX in CS-NPs via ionic gelation method, resulted in particles of 157.8 ± 3.85 nm in size and an entrapment efficiency (EE) of 86.44 ± 2.19 %. Moreover, AMX-CS NPs showed a sustained drug release pattern over 72 h with no detectable toxicity on human dermal fibroblasts cell lines. Encapsulation of AMX into CS NPs also reduced its MIC50 against H. pylori, while its co-administration with inulin maintained L. casei viability. Interestingly, treatment with AMX-CS NPs also reduced the expression of the efflux pump gene hefA in H. pylori. This dual treatment strategy offers a promising approach for more selective antimicrobial treatment, minimizing disruption to healthy microbial communities while effectively addressing pathogenic threats.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

Chitosan has received much attention for its role in designing and developing novel derivatives as well as its applications across a broad spectrum of biological and physiological activities, owing to its desirable characteristics such as being biodegradable, being a biopolymer, and its overall eco-friendliness. The main objective of this review is to explore the recent chemical modifications of chitosan that have been achieved through various synthetic methods. These chitosan derivatives are categorized based on their synthetic pathways or the presence of common functional groups, which include alkylated, acylated, Schiff base, quaternary ammonia, guanidine, and heterocyclic rings. We have also described the recent applications of chitosan and its derivatives, along with nanomaterials, their mechanisms, and prospective challenges, especially in areas such as antimicrobial activities, targeted drug delivery for various diseases, and plant agricultural domains. The accumulation of these recent findings has the potential to offer insight not only into innovative approaches for the preparation of chitosan derivatives but also into their diverse applications. These insights may spark novel ideas for drug development or drug carriers, particularly in the antimicrobial, medicinal, and plant agricultural fields.

Liquid crystalline lipid nanoparticles improve the antibacterial activity of tobramycin and vancomycin against intracellular Pseudomonas aeruginosa and Staphylococcus aureus

The intracellular survival of bacteria is a significant challenge in the fight against antimicrobial resistance. Currently available antibiotics suffer from limited penetration across host cell membranes, resulting in suboptimal treatment against the internalised bacteria. Liquid crystalline nanoparticles (LCNP) are gaining significant research interest in promoting the cellular uptake of therapeutics due to their fusogenic properties; however, they have not been reported for targeting intracellular bacteria. Herein, the cellular internalisation of LCNPs in RAW 264.7 macrophages and A549 epithelial cells was investigated and optimized through the incorporation of a cationic lipid, dimethyldioctadecylammonium bromide (DDAB). LCNPs displayed a honeycomb-like structure, while the inclusion of DDAB resulted into an onion-like organisation with larger internal pores. Cationic LCNPs enhanced the cellular uptake in both cells, reaching up to ∼90% uptake in cells. Further, LCNPs were encapsulated with tobramycin or vancomycin to improve their activity against intracellular gram-negative, Pseudomonas aeruginosa (P. aeruginosa) and gram-positive, Staphylococcus aureus (S. aureus) bacteria. The enhanced cellular uptake of cationic LCNP resulted in significant reduction of intracellular bacterial load (up to 90% reduction), compared to antibiotic dosed in its free form; with reduced performance observed for epithelial cells infected with S. aureus. Specifically engineered LCNP can re-sensitise antibiotics against both intracellular Gram positive and negative bacteria in diverse cell lines.

Chitosan loaded RNA polymerase inhibitor nanoparticles increased attenuation in toxin release from Streptococcus pneumonia

Background

Multidrug-resistant (MDR) bacterial infections have become an emerging health concern around the world. Antibiotics resistance among S. pneumoniae strains increased recently contributing to increase in incidence of pneumococcal infection. This necessitates the discovery of novel antipnemococcal such as compound C3-005 which target the interaction between RNA polymerase and σ factors. Chitosan nanoparticles (CNPs) exhibited antibacterial activity including S. pneumonia. Therefore, the aims of the current investigation were to formulate CNPs loaded with C3-005 and characteristic their antimicrobial properties against S. pneumonia.

Methods

The CNPs and C3-005 loaded CNPs were produced utilizing ionic gelation method, and their physicochemical characteristics including particle size, zeta potential, polydispersity index (PDI), encapsulation efficiency (EE%), and in vitro release profile were studied. Both differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy (FTIR) were used for chemical characterization. The synthesized NPs' minimum inhibitory concentration (MIC) was determined using killing assay and broth dilution method, and their impact on bacteria induced hemolysis were also studied.

Results

The NPs encapsulating C3-005 were successfully prepared with particle size of 343.5 nm ± 1.3, zeta potential of 29.8 ± 0.37, and PDI of 0.20 ± 0.03. 70 % of C3-005 were encapsulated in CNPs and sustained release pattern of C3-005 from CNPs was revealed by an in vitro release study. CNPs containing C3-005 exhibited higher antipnomcoccal activity with MIC₅₀ of 30 µg/ml when compared with C3-005 and empty CNPs alone. The prepared C3-CNPs showed a reduction of bacterial hemolysis in a concentration-related (dependent) manner and was higher than C3-005 alone.

Conclusions

The findings of this study showed the potential for using C3-005 loaded CNPs to treat pneumococcal infection.

Development and Optimization of Ciprofloxacin HCl-Loaded Chitosan Nanoparticles Using Box–Behnken Experimental Design

Various chitosan (CS)-based nanoparticles (CS-NPs) of ciprofloxacin hydrochloride (CHCl) have been investigated for therapeutic delivery and to enhance antimicrobial efficacy. However, the Box–Behnken design (BBD)-supported statistical optimization of NPs of CHCl has not been performed in the literature. As a result, the goal of this study was to look into the key interactions and quadratic impacts of formulation variables on the performance of CHCl-CS-NPs in a systematic way. To optimize CHCl-loaded CS-NPs generated by the ionic gelation process, the response surface methodology (RSM) was used. The BBD was used with three factors on three levels and three replicas at the central point. Tripolyphosphate, CS concentrations, and ultrasonication energy were chosen as independent variables after preliminary screening. Particle size (PS), polydispersity index (PDI), zeta potential (ZP), encapsulation efficiency (EE), and in vitro release were the dependent factors (responses). Prepared NPs were found in the PS range of 198–304 nm with a ZP of 27–42 mV. EE and drug release were in the range of 23–45% and 36–61%, respectively. All of the responses were optimized at the same time using a desirability function based on Design Expert® modeling and a desirability factor of 95%. The minimum inhibitory concentration (MIC) of the improved formula against two bacterial strains, Pseudomonas aeruginosa and Staphylococcus aureus, was determined. The MIC of the optimized NPs was found to be decreased 4-fold compared with pure CHCl. The predicted and observed values for the optimized formulation were nearly identical. The BBD aided in a better understanding of the intrinsic relationship between formulation variables and responses, as well as the optimization of CHCl-loaded CS-NPs in a time- and labor-efficient manner.

Misdiagnosis of COVID-19 infection before molecular confirmation in Sulaimaniyah City, Iraq

Background

During the last 2 years, in the Kurdistan Region, Northern Iraq, there were thousands of COVID-19 cases that have not been reported officially, but diagnosed and confirmed by private laboratories and private hospitals, or clinicians based on typical clinical signs, as well as few people using home self-test after appearing of some flu-like clinical symptoms. Thus, this study aims to assess the misdiagnosis and mismanagement of cases before COVID-19 confirmation.

Methods

This study enrolled 100 consecutive patients who visited an outpatient clinic of Shar Hospital that had symptoms highly suspicious of COVID-19 infection while misdiagnosed previously to have other types of disease. Detailed questionnaires were filled for all studied patients, including age, gender, main presenting symptoms, and duration of these symptoms with the following questions: who made the false diagnosis, depending on which diagnostic test the false diagnosis was made, which medication was used for the false diagnosis, who prescribed those medications, and how long those medications were used. They were investigated by RT-PCR on their nasopharyngeal swab for confirmation.

Results

Most of the false diagnoses were typhoid (63%), influenza (14%), pneumonia (9%), gastroenteritis (5%), common cold (4%), brucellosis (4%), and meningitis (1%). Regarding the false diagnosis of cases, 92% were made by non-physician healthcare workers, and only 8% were made by physicians. All false diagnoses with typhoid, gastroenteritis, and common cold were made by non-physician healthcare workers, together with about half of the diagnosis of pneumonia and brucellosis, with statistically significant results (P < 0.001).

Conclusions

We realized that some patients had been misdiagnosed before the COVID-19 infection confirmation. Their health conditions improved drastically after correct diagnosis and treatment, and this research is considered the first research to be conducted in Iraq in this regard.

Meta-Analysis of Drug Delivery Approaches for Treating Intracellular Infections

This meta-analysis aims to evaluate the trend, methodological quality and completeness of studies on intracellular delivery of antimicrobial agents. PubMed, Embase, and reference lists of related reviews were searched to identify original articles that evaluated carrier-mediated intracellular delivery and pharmacodynamics (PD) of antimicrobial therapeutics against intracellular pathogens in vitro and/or in vivo. A total of 99 studies were included in the analysis. The most commonly targeted intracellular pathogens were bacteria (62.6%), followed by viruses (16.2%) and parasites (15.2%). Twenty-one out of 99 (21.2%) studies performed neither microscopic imaging nor flow cytometric analysis to verify that the carrier particles are present in the infected cells. Only 31.3% of studies provided comparative inhibitory concentrations against a free drug control. Approximately 8% of studies, albeit claimed for intracellular delivery of antimicrobial therapeutics, did not provide any experimental data such as microscopic imaging, flow cytometry, and in vitro PD. Future research on intracellular delivery of antimicrobial agents needs to improve the methodological quality and completeness of supporting data in order to facilitate clinical translation of intracellular delivery platforms for antimicrobial therapeutics.

Different Nanotechnology Approaches for Ciprofloxacin Delivery Against Multidrug-Resistant Microbes

The percentages of organisms exhibiting antimicrobial resistance, especially resistance to multiple antibiotics, are incessantly increasing. Studies investigated that many bacteria are being resistant to ciprofloxacin. This review addresses the current knowledge on nano-based ciprofloxacin delivery approaches to improve its effectiveness and overcome the resistance issues. Ciprofloxacin delivery can be modified by encapsulating with or incorporating in different polymeric nanoparticles such as chitosan, PLGA, albumin, arginine, and other organic and inorganic nanostructure systems. Most of these nano-approaches are promising as an alternative strategy to improve the therapeutic effectiveness of ciprofloxacin in the future.

Antimicrobial Properties of Chitosan and Chitosan Derivatives in the Treatment of Enteric Infections

Antibiotics played an important role in controlling the development of enteric infection. However, the emergence of antibiotic resistance and gut dysbiosis led to a growing interest in the use of natural antimicrobial agents as alternatives for therapy and disinfection. Chitosan is a nontoxic natural antimicrobial polymer and is approved by GRAS (Generally Recognized as Safe by the United States Food and Drug Administration). Chitosan and chitosan derivatives can kill microbes by neutralizing negative charges on the microbial surface. Besides, chemical modifications give chitosan derivatives better water solubility and antimicrobial property. This review gives an overview of the preparation of chitosan, its derivatives, and the conjugates with other polymers and nanoparticles with better antimicrobial properties, explains the direct and indirect mechanisms of action of chitosan, and summarizes current treatment for enteric infections as well as the role of chitosan and chitosan derivatives in the antimicrobial agents in enteric infections. Finally, we suggested future directions for further research to improve the treatment of enteric infections and to develop more useful chitosan derivatives and conjugates.

Bioinspired drug delivery strategies for repurposing conventional antibiotics against intracellular infections

Bacteria have developed a wealth of strategies to avoid and resist the action of antibiotics, one of which involves pathogens invading and forming reservoirs within host cells. Due to the poor cell membrane permeability, stability and retention of conventional antibiotics, this renders current treatments largely ineffective, since achieving a therapeutically relevant antibiotic concentration at the site of intracellular infection is not possible. To overcome such challenges, current antibiotics are 'repurposed' via reformulation using micro- or nano-carrier systems that effectively encapsulate and deliver therapeutics across cellular membranes of infected cells. Bioinspired materials that imitate the uptake of biological particulates and release antibiotics in response to natural stimuli are recently explored to improve the targeting and specificity of this 'nanoantibiotic' approach. In this review, the mechanisms of internalization and survival of intracellular bacteria are elucidated, effectively accentuating the current treatment challenges for intracellular infections and the implications for repurposing conventional antibiotics. Key case studies of nanoantibiotics that have drawn inspiration from natural biological particles and cellular uptake pathways to effectively eradicate intracellular pathogens are detailed, clearly highlighting the rational for harnessing bioinspired drug delivery strategies.

Design and Optimization of New Enteric Nanoparticles of Ceftriaxone for Oral Delivery: In vitro and in vivo Assessments

PURPOSE

Development of new strategies for oral delivery of existing antibiotics administered exclusively through intravenous route is one of the global priorities of pharmaceutical research. The encapsulation of these active pharmaceutical agents within nanosized natural products offers several traits due to their tunable surface properties. Ceftriaxone (CTX) is an injectable, third-generation cephalosporin that suffers poor oral bioavailability.

METHODS

In the present study, ionic gelation of two biopolymers, namely chitosan (CH) and shellac (SH), was implemented to consolidate CTX, within elegant nanoparticles (NPs) for oral administration that would increase its bioavailability and sustainability. Quality by design approach (23 full factorial design) was adopted to optimize CTX-loaded nanoparticles. The optimized formula (F2) was characterized through transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). In vitro release behavior and stability study were also evaluated. Pharmacokinetic studies of enteric-coated hard gelatin capsules (HGCs) loaded with F2-NPs were finally assessed.

RESULTS

The optimized spherical F2-NPs had a mean particle size of 258 nm, zeta potential of about +30.1 and appreciable drug entrapment efficiency of 83%. The in vitro drug release profile of F2-NPs in pH 7.4 experienced biphasic configuration with an initial burst release for an hour, followed by a sustained release over 15 h with Higuchi model and non-Fickian diffusion mechanism (R2=0.9852). High stability upon storage at refrigerated and room temperature for 3 months and good flow properties (θ= 32.2 and HR= 1.13) of the optimized formula were also conferred. In vivo pharmacokinetic assessment in rabbits fruitfully displayed 92% absolute bioavailability of CTX.

CONCLUSION

The obtained results provide evidence for the potential combination of CH and SH in NPs preparation to enhance the oral bioavailability of CTX.

The contribution of nano-based strategies in overcoming ceftriaxone resistance: a literature review

Antimicrobial drug resistance, including resistance to multiple antibiotics, is continuously increasing. According to research findings, many bacteria resistant to other antibiotics were susceptible to ceftriaxone. However, over the last few years, ceftriaxone resistance has become growing and extremely worrisome challenge to the global healthcare system and several strategies have been initiated to contain the spread of antimicrobial drug resistance. Its extended use for therapeutic or preventative measures in humans and farm animals resulted in the development and spread of resistance. Recent advances in nanotechnology also offer novel formulations based on distinct types of nanostructure particles with different sizes and shapes, and flexible antimicrobial properties. For ceftriaxone, several nanostructured formulations through conjugation, intercalation, encapsulation with lipid carrier, and polymeric films have been investigated by different groups with promising results in combating the development of resistance. This review addressed the existing knowledge and practice on the contribution of nano-based delivery approaches in overcoming ceftriaxone resistance. Evidences have been generated from published research articles using major search electronic databases such as PubMed, Medline, Google Scholar, and Science Direct.

Colloidal nanosystems with mucoadhesive properties designed for ocular topical delivery

Over the last years, the scientific interest about topical ocular delivery targeting the posterior segment of the eye has been increasing. This is probably due to the fact that this is a non-invasive administration route, well tolerated by patients and with fewer local and systemic side effects. However, it is a challenging task due to the external ocular barriers, tear film clearance, blood flow in the conjunctiva and choriocapillaris and due to the blood-retinal barriers, amongst other features. An enhanced intraocular bioavailability of drugs can be achieved by either improving corneal permeability or by improving precorneal retention time. Regarding this last option, increasing residence time in the precorneal area can be achieved using mucoadhesive polymers such as xyloglucan, poly(acrylate), hyaluronic acid, chitosan, and carbomers. On the other hand, colloidal particles can interact with the ocular mucosa and enhance corneal and conjunctival permeability. These nanosystems are able to deliver a wide range of drugs, including macromolecules, providing stability and improving ocular bioavailability. New pharmaceutical approaches based on nanotechnology associated to bioadhesive compounds have emerged as strategies for a more efficient treatment of ocular diseases. Bearing this in mind, this review provides an overview of the current mucoadhesive colloidal nanosystems developed for ocular topical administration, focusing on their advantages and limitations.

Synthesis, characterization and drug delivery application of Dapsone based double tailed biocompatible nonionic surfactant

The increase in antimicrobial resistance has created a crisis that has become top priority for global policy and public health. Antibiotics are constantly being rendered in-effective due to the emergence of bacterial resistance; therefore, novel strategies for improving therapeutic efficacies of existing drugs must be focused. Advancements in nanotechnology have opened up new avenues for enhancing therapeutic efficacy of existing drugs via construction of intelligent and efficient delivery systems. This study reports the synthesis of Dapsone based nonionic surfactant and its utilization as delivery system for Ceftriaxone sodium. The synthesized nonionic surfactant was characterized via mass spectrometry and ¹H NMR and IR spectroscopic techniques. The drug loaded vesicles of newly synthesized sulfur based nonionic were formed through thin film hydration method and characterized for drug entrapment efficiency, vesicles size, zeta potential, morphology using UV-vis spectrometry, dynamic light scattering (DLS) and atomic force microscopic (AFM) techniques. The biocompatibility of newly synthesized surfactant was assessed using blood hemolysis and in-vitro cells cytotoxicity. Antibacterial potential of drug loaded vesicles was assessed in gram positive and gram negative bacterial cultures. The spectroscopic results confirm successful synthesis of novel sulfur based nonionic surfactant that formed spherical shaped drug loaded vesicles with an average size of 97.95 ± 3.45 nm and 56.3 ± 3.15 % entrapment of the model drug (Ceftriaxone sodium). The vesicles displayed negative surface charge of -16.8 ± 3.72 mV and released the entrapped drug in a controlled way in-vitro drug release. The drug loaded vesicular formulation showed enhanced cellular uptake and greater antibacterial potentials when compared with control. Results of this study show that the Dapsone based surfactant is safe, biocompatible, non-toxic and can be used as promising vesicular carrier for enhancing therapeutic efficacy of antibacterial drug, Ceftriaxone sodium.

Enhanced Antibacterial Activity Of Doxycycline And Rifampicin Combination Loaded In Nanoparticles Against Intracellular Brucella Abortus

BACKGROUND

Brucellosis is a zoonotic disease and prevalent in livestock animals. The bacteria reside inside the macrophage cells of host. The WHO endorsed the combination treatment therapy for brucellosis as compared to monotherapy to avoid relapse and resistance. Therefore, we developed nanoparticles incorporating doxycycline and rifampicin in combination.

OBJECTIVE

The aim of the study is to develop polymeric nanoparticles incorporating doxycycline as well as rifampicin and investigate the antibacterial activity of nanoparticles in U937 human macrophage cells infected with B. abortus.

METHODS

Polymeric nanoparticles were developed by emulsion-solvent diffusion method and characterization was done.

RESULTS

The nanoparticles with high entrapment efficiency of both drugs were developed successfully. Scanning electron microscopy revealed spherical morphology with a size ranging ~450nm, which can be easily engulfed by macrophages. Zeta potential confirmed colloidal stability. Differential scanning calorimetry and X-ray diffraction suggested amorphization of doxycycline and rifampicin in nanoparticles. Fourier transfer infrared spectroscopy could not confirm interaction of drugs with AOT. In vitro haemolysis study confirmed safety of nanoparticles (<10%) for IV administration. Further, nanoparticles revealed the sustained release of both drugs, which followed diffusion kinetics. Nanoparticles were found stable for 6 months as per WHO guidelines. The internalization study revealed nanoparticles can be easily uptake by U-937 human macrophage cells. The efficacy study demonstrated significantly high antibacterial activity of nanoparticles as compared to free drug solution in U937 human macrophage cells infected with Brucella abortus.

CONCLUSION

It can be concluded that developed nanoparticles entrapping doxycycline and rifampicin combination could be considered as a promising delivery system for enhancing the antibacterial activity against Brucella abortus.

Metal/metal oxide nanocomposites for bactericidal effect: A review

Many microbial species causing infectious disease all over the world became a social burden and creating threat among community. These microbes possess long lifetime, enhancing mortality and morbidity rate in affected organisms. In this condition, the treatment was ineffective and more chances of spreading of infection into other organisms. Hence, it is necessary to initiate infection control efforts and prevention activities against multidrug resistant microbes, to reduce the death rate of people. Seriously concerning towards this problem progress was shown in developing significant drugs with least side effects. Emergence of nanoparticles and its novelty showed effective role in targeting and destructing microbes well. Further, many research works have shown nanocomposites developed from nanoparticles coupled with other nanoparticles, polymers, carbon material acted as an exotic substance against microbes causing severe loss. However, metal and metal oxide nanocomposites have gained interest due to its small size and enhancing the surface contact with bacteria, producing damage to it. The bactericidal mechanism of metal and metal oxide nanocomposites involve in the production of reactive oxygen species which includes superoxide radical anions, hydrogen peroxide anions and hydrogen peroxide which interact with the cell wall of bacteria causing damage to the cell membrane in turn inhibiting the further growth of cell with leakage of internal cellular components, leading to death of bacteria. This review provides the detailed view on antibacterial activity of metal and metal oxide nanocomposite which possessed novelty due to its physiochemical changes.

The Pharmacodynamics Study of Insect Defensin DLP4 Against Toxigenic Staphylococcus hyicus ACCC 61734 in Vitro and Vivo

Staphylococcus hyicus (S. hyicus), as the main pathogen of exudative epidermitis (EE) in piglet, can cause a wide variety of diseases, ranging from bovine mastitis, chicken arthritis and even human sepsis, which has brought serious threats to animals and human. The potential threat of S. hyicus infection to both public and animal health has aroused great concern. The aim of our study was to explore the efficacy of insect defensin DLP4 against S. hyicus ACCC 61734 in vitro and in vivo. The in vitro efficacies of DLP4 against S. hyicus ACCC 61734 showed high antibacterial activity (0.92 μM), a long postantibiotic effect (9.54 h), a synergistic effect with ceftriaxone, penicillin and amoxicillin, a stable bacteriostatic effect, and intracellular bacteriostatic activity against S. hyicus ACCC 61734 in HaCaT cells. Besides, the antibacterial mechanism of DLP4 against S. hyicus ACCC 61734 was explored for the first time, which indicated that the antibacterial effect of DLP4 was related to its ability to destroy cell wall and generate membrane vesicles. The in vivo therapeutic effect of DLP4 was evaluated through mouse abscess model, and the results showed that DLP4 could effectively alleviate the mouse skin abscess by inhibiting bacterial proliferation and regulating cytokines. This study first demonstrated that DLP4 may be a promising therapeutic agent against S. hyicus ACCC 61734 infection.

Galactosylated iron oxide nanoparticles for enhancing oral bioavailability of ceftriaxone

The current study focuses on the development, characterization, biocompatibility investigation and oral bioavailability evaluation of ceftriaxone (CFT)-loaded lactobionic acid (LBA)-functionalized iron oxide magnetic nanoparticles (MNP-LBA). Atomic force microscopy and dynamic light scattering showed that the developed CFT-loaded MNP-LBA is spherical, with a measured hydrodynamic size of 147 ± 15.9 nm and negative zeta potential values (-35 ± 0.58 mV). Fourier transformed infrared analysis revealed interactions between the nanocarrier and the drug. Nanoparticles showed high drug entrapment efficiencies of 91.5 ± 2.2%, and the drug was released gradually in vitro and shows prolonged in vitro stability using simulated gastrointestinal (GI) fluids. The formulations were found to be highly biocompatible (up to 100 µg/mL) and hemocompatible (up to 1.0 mg/mL). Using an albino rabbit model, the formulation showed a significant enhancement in drug plasma concentration up to 14.46 ± 2.5 µg/mL in comparison with its control (1.96 ± 0.58 µg/mL). Overall, the developed MNP-LBA formulation was found promising for provision of high-drug entrapment, gradual drug release and was appropriate for enhancing the oral delivery of CFT.

Third-Generation Cephalosporin-Loaded Chitosan Used to Limit Microorganisms Resistance

From their discovery, antibiotics have significantly improved clinical treatments of infections, thus leading to diminishing morbidity and mortality in critical care patients, as well as surgical, transplant and other types of medical procedures. In contemporary medicine, a significant debate regarding the development of multi-drug resistance involves all types of pathogens, especially in acute care hospitals due to suboptimal or inappropriate therapy. The possibility of nanotechnology using nanoparticles as matrices to encapsulate a lot of active molecules should increase drug efficacy, limit adverse effects and be an alternative helping to combat antibiotic resistance. The major aim of this study was to obtain and to analyze physico-chemical features of chitosan used as a drug-delivery system in order to stop the antibiotic resistance of different pathogens. It is well known that World Health Organization stated that multidrug resistance is one of the most important health threats worldwide. In last few years, nano-medicine emerged as an improved therapy to combat antibiotic-resistant infections agents. This work relies on enhancement of the antimicrobial efficiency of ceftriaxone against gram(+) and gram(-) bacteria by antibiotic encapsulation into chitosan nanoparticles. Physicochemical features of ceftriaxone-loaded polymer nanoparticles were investigated by particle size distribution and zeta potential, Fourier-transform infrared spectroscopy (FTIR), Thermal Gravimetric Analysis (TG/TGA), Scanning Electron Microscopy (SEM) characteristics techniques. The obtained results revealed an average particle size of 250 nm and a zeta potential value of 38.5 mV. The release profile indicates an incipient drug deliverance of almost 15%, after 2 h of approximately 83%, followed by a slowed drug release up to 24 h. Characteristics peaks of chitosan were confirmed by FTIR spectra indicating a similar structure in the case of ceftriaxone-loaded chitosan nanoparticles. A good encapsulation of the antibiotic into chitosan nanoparticles was also provided by thermo-gravimetric analysis. Morphological characteristics shown by SEM micrographs exhibit spherical nanoparticles of 30-250 nm in size with agglomerated architectures. Chitosan, a natural polymer which is used to load different drugs, provides sustained and prolonged release of antibiotics at a specific target by possessing antimicrobial activity against gram(+) and gram(-) bacteria. In this research, ceftriaxone-loaded chitosan nanoparticles were investigated as a carrier in antibiotic delivery.

Polymeric Nanoparticle Associated with Ceftriaxone and Extract of Schinopsis Brasiliensis Engler against Multiresistant Enterobacteria

Bacterial resistance has become an important public health problem. Bacteria have been acquiring mechanisms to resist the action of antimicrobial active pharmaceutical ingredients (API). Based on this, a promising alternative is the use of nanotechnology, since when the systems are presented in nanometric size, there is an increase in the interaction and concentration of the action at the target site improving the activity. Thus, this study aims to develop a polymeric nanoparticle (PN) composed of chitosan and hydroxypropylmethylcellulose, as an innovative strategy for the administration of an association between ceftriaxone and extract of S. brasiliensis, for the treatment of Enterobacteriaceae. From a Box-Behnken design, nanoparticles were obtained and evaluated using the DLS technique, obtaining the particle size between 440 and 1660 nm, IPD from 0.42 to 0.92, and positive charges. Morphological characteristics of PN by SEM revealed spherical morphology and sizes similar to DLS. Infrared spectroscopy showed no chemical interaction between the components of the formulation. The broth microdilution technique evaluated their antimicrobial activity, and a considerable improvement in the activity of the extract and the API compared to the free compounds was found, reaching an improvement of 133 times in the minimum inhibitory activity CRO.

Drug delivery to macrophages: a review of nano-therapeutics targeted approach for inflammatory disorders and cancer

INTRODUCTION

Macrophages are involved in the normal defense of the body; however, the varying phenotypes of macrophages and imbalance in their ratio lead to the impairment of immune response initiating the production of inflammation. As the role of macrophages in immunological disorders and their surface receptors modulation has already been manifested; hence, macrophages can be exploited to make them a viable candidate for targeted delivery, which was not possible with previously designed conventional therapies for the immune disorders.

AREAS COVERED

Nanotechnology is a promising, clear cut, efficient, and adequate approach for targeting macrophages. Literature addresses the receptors available for targeting and the novel small dimensional therapeutic delivery vehicles to target them along with a brief overview of the role of macrophages in these diseases. Furthermore, the patents based on this idea are also listed.

EXPERT OPINION

Targeted drug delivery to macrophages should take into consideration the plasticity of macrophages and their modulation over time in the diseases. A cost-effective scale-up method of development will further facilitate the clinical trials. Besides, the implementation of safety guidelines to target macrophages and the studies of long-term effects of targeted approaches in humans would highly encourage the clinical outcomes.

Enhancement in Oral Absorption of Ceftriaxone by Highly Functionalized Magnetic Iron Oxide Nanoparticles

The present study aims at the development, characterization, biocompatibility investigation and oral bioavailability evaluation of ceftriaxone (CFT)-loaded N′-methacryloylisonicotinohydrazide (MIH)-functionalized magnetic nanoparticles (CFT-MIH-MNPs). Atomic force microscopy (AFM) and dynamic light scattering (DLS) showed that the developed CFT loaded MIH-MNPs are spherical, with a measured hydrodynamic size of 184.0 ± 2.7 nm and negative zeta potential values (–20.2 ± 0.4 mV). Fourier transformed infrared spectroscopic (FTIR) analysis revealed interactions between the nanocarrier and the drug. Nanoparticles showed high drug entrapment efficiency (EE) of 79.4% ±1.5%, and the drug was released gradually in vitro and showed prolonged in vitro stability using simulated gastrointestinal tract (GIT) fluids. The formulations were found to be highly biocompatible (up to 100 µg/mL) and hemocompatible (up to 1.0 mg/mL). Using an albino rabbit model, the formulation showed a significant enhancement in drug plasma concentration up to 14.4 ± 1.8 µg/mL in comparison with its control (2.0 ± 0.6 µg/mL). Overall, the developed CFT-MIH-MNPs formulation was promising for provision of high drug entrapment, gradual drug release and suitability for enhancing the oral delivery of CFT.

Multi-functionalized nanocarriers targeting bacterial reservoirs to overcome challenges of multi drug-resistance

INTRODUCTION

Infectious diseases associated with intracellular bacteria such as Staphylococcus aureus, Salmonella typhimurium and Mycobacterium tuberculosis are important public health concern. Emergence of multi and extensively drug-resistant bacterial strains have made it even more obstinate to offset such infections. Bacteria residing within intracellular compartments provide additional barriers to effective treatment.

METHOD

Information provided in this review has been collected by accessing various electronic databases including Google scholar, Web of science, Scopus, and Nature index. Search was performed using keywords nanoparticles, intracellular targeting, multidrug resistance, Staphylococcus aureus; Salmonella typhimurium; Mycobacterium tuberculosis. Information gathered was categorized into three major sections as 'Intracellular targeting of Staphylococcus aureus, Intracellular targeting of Salmonella typhimurium and Intracellular targeting of Mycobacterium tuberculosis' using variety of nanocarrier systems.

RESULTS

Conventional management for infectious diseases typically comprises of long-term treatment with a combination of antibiotics, which may lead to side effects and decreased patient compliance. A wide range of multi-functionalized nanocarrier systems have been studied for delivery of drugs within cellular compartments where bacteria including Staphylococcus aureus, Salmonella typhimurium and Mycobacterium tuberculosis reside. Such carrier systems along with targeted delivery have been utilized for sustained and controlled delivery of drugs. These strategies have been found useful in overcoming the drawbacks of conventional treatments including multi-drug resistance.

CONCLUSION

Development of multi-functional nanocargoes encapsulating antibiotics that are proficient in targeting and releasing drug into infected reservoirs seems to be a promising strategy to circumvent the challenge of multidrug resistance. Graphical abstract.

Physico-Chemically Distinct Nanomaterials Synthesized from Derivates of a Poly(Anhydride) Diversify the Spectrum of Loadable Antibiotics

Recent advances in the field of nanotechnology such as nanoencapsulation offer new biomedical applications, potentially increasing the scope and efficacy of therapeutic drug delivery. In addition, the discovery and development of novel biocompatible polymers increases the versatility of these encapsulating nanostructures, enabling chemical properties of the cargo and vehicle to be adapted to specific physiological requirements. Here, we evaluate the capacity of various polymeric nanostructures to encapsulate various antibiotics of different classes, with differing chemical structure. Polymers were sourced from two separate derivatives of poly(methyl vinyl ether-alt-maleic anhydride) (PMVE/MA): an acid (PMVE/MA-Ac) and a monoethyl ester (PMVE/MA-Es). Nanoencapsulation of antibiotics was attempted through electrospinning, and nanoparticle synthesis through solvent displacement, for both polymers. Solvent incompatibilities prevented the nanoencapsulation of amikacin, neomycin and ciprofloxacin in PMVE/MA-Es nanofibers. However, all compounds were successfully loaded into PMVE/MA-Es nanoparticles. Encapsulation efficiencies in nanofibers reached approximately 100% in all compatible systems; however, efficiencies varied substantially in nanoparticles systems, depending on the tested compound (14%-69%). Finally, it was confirmed that both these encapsulation processes did not alter the antimicrobial activity of any tested antibiotic against Staphylococcus aureus and Escherichia coli, supporting the viability of these approaches for nanoscale delivery of antibiotics.

Study on antibiotic susceptibility of Salmonella typhimurium L forms to the third and forth generation cephalosporins

Salmonella typhimurium is a pathogenic gram-negative bacterium, which is found primarily in the intestinal lumen. It often causes diarrhea in infants and young children and leads to food poisoning. Drug resistance of Salmonella typhimurium presented serious complications in clinical patients. In this study, we investigated the antibiotic susceptibility of Salmonella typhimurium standard strain L forms to the third and forth generation cephalosporins, in order to control and eliminate Salmonella typhimurium L forms in infection treatment. Salmonella typhimurium L forms were induced by β-lactam antibiotic cefazolin in the culture medium of bacterial L forms. The antibiotic susceptibility of Salmonella typhimurium L forms was analyzed by K-B drug susceptibility testing. The change trend of drug susceptibility and resistance of Salmonella typhimurium L forms was obtained in accordance with USA clinical and laboratory standards institute (CLSI) evaluation data and statistical analysis. Drug resistance of Salmonella typhimurium L forms showed little increasing trend compared with their parent bacteria. The L form inhibition zone was smaller than in the parent bacteria. However, the drug susceptibility of L forms of Salmonella typhimurium to the third and forth generation cephalosporins remained sensitive.The antibiotic susceptibility of Salmonella typhimurium L forms to the third and forth generation cephalosporins remains sensitive, and the combined use of multi-antibiotics is a convenient and effective method to reduce Salmonella typhimurium L forms occurrence.

Nanomaterials and nanocomposite applications in veterinary medicine

Nowadays, nanotechnology has made huge, significant advancements in biotechnology and biomedicine related to human and animal science, including increasing health safety, production, and the elevation of national income. There are various fields of nanomaterial applications in veterinary medicine such as efficient diagnostic and therapeutic tools, drug delivery, animal nutrition, breeding and reproduction, and valuable additives. Additional benefits include the detection of pathogens, protein, biological molecules, antimicrobial agents, feeding additives, nutrient delivery, and reproductive aids. There are many nanomaterials and nanocomposites that can be used in nanomedicine such as metal nanoparticles, liposomes, carbon nanotubes, and quantum dots. In the near future, nanotechnology research will have the ability to produce novel tools for improving animal health and production. Therefore, this chapter was undertaken to spotlight novel methods created by nanotechnology for application in the improvement of animal health and production. In addition, the toxicity of nanomaterials is fully discussed to avoid the suspected health hazards of toxicity for animal health safety.

Carbohydrate-based nanocarriers and their application to target macrophages and deliver antimicrobial agents

Many deadly infections are produced by microorganisms capable of sustained survival in macrophages. This reduces exposure to chemadrotherapy, prevents immune detection, and is akin to criminals hiding in police stations. Therefore, the use of glyco-nanoparticles (GNPs) as carriers of therapeutic agents is a burgeoning field. Such an approach can enhance the penetration of drugs into macrophages with specific carbohydrate targeting molecules on the nanocarrier to interact with macrophage lectins. Carbohydrates are natural biological molecules and the key constituents in a large variety of biological events such as cellular communication, infection, inflammation, enzyme trafficking, cellular migration, cancer metastasis and immune functions. The prominent characteristics of carbohydrates including biodegradability, biocompatibility, hydrophilicity and the highly specific interaction of targeting cell-surface receptors support their potential application to drug delivery systems (DDS). This review presents the 21^st century development of carbohydrate-based nanocarriers for drug targeting of therapeutic agents for diseases localized in macrophages. The significance of natural carbohydrate-derived nanoparticles (GNPs) as anti-microbial drug carriers is highlighted in several areas of treatment including tuberculosis, salmonellosis, leishmaniasis, candidiasis, and HIV/AIDS.

Repurposing salicylamide for combating multidrug-resistant Neisseria gonorrhoeae

The U.S. Centers for Disease Control and Prevention (CDC) lists Neisseria gonorrhoeae as one of the most urgent antibiotic-resistant threats in the United States. This is due to the emergence of clinical isolates that have developed resistance to nearly every antibiotic used to treat gonorrhea and highlights the critical need to find new therapeutics. The present study discovered salicylamide, an analgesic and antipyretic drug, has antibacterial activity against 40 different antibiotic-resistant strains of N. gonorrhoeae (MIC 8-32 μg/ml) with low frequency of resistance <2.4x10^-9 Interestingly, salicylamide did not inhibit growth of bacterial species in the vaginal microflora involved in defense against gonococcal infections, such as Lactobacillus gasseri, L. jensenii, L. johnsonii, and L. crispatus A time-kill assay revealed that salicylamide is a rapidly bactericidal drug as it eradicated a high inoculum of N. gonorrhoeae within 10 hours. Salicylamide was superior to the drug of choice, ceftriaxone, in reducing the burden of intracellular N. gonorrhoeae by 97% in infected endocervical cells. Furthermore, salicylamide outperformed ceftriaxone in reducing expression of the pro-inflammatory cytokine IL-8 from endocervical cells infected with N. gonorrhoeae A checkerboard assay revealed that salicylamide exhibited a synergistic interaction with tetracycline and an additive relationship with azithromycin and ciprofloxacin, and ceftriaxone. A more in-depth investigation of the structure-activity-relationship of derivatives of salicylamide revealed the amide and hydroxyl groups are important for anti-gonorrheal activity. In conclusion, this study identified salicylamide as a promising candidate for further investigation as a novel treatment option for multidrug-resistant gonorrhea.

New Perspective Enteric-Coated Tablet Dosage Form for Oral Administration of Ceftriaxone: In Vitro and In Vivo Assessments

Ceftriaxone (CTX) is a widely used injectable third-generation cephalosporin that exhibits broad-spectrum antibacterial activity. Unfortunately, the oral route of this drug suffers different encumbrances, such as instability in the upper part of the GIT and enzymatic degradation, as well as poor permeability. There is no reported tablet dosage form for this drug. In this respect, the authors investigated the possibility of developing an enteric-coated oral tablet of CTX that would be helpful for better patient compliance. The tablet consists of directly compressed core of CTX, citric acid (CA), sodium chloride (NaCl), and two biopolymers-chitosan (CH), a permeation enhancer, and silicified microcrystalline cellulose (SMCC), a wicking agent. Both biopolymers are naturally occurring polysaccharides that are biodegradable in the colon and able to incorporate acid labile drugs. CA is a pH modulator to protect CTX from protease enzymes, while NaCl is a translocation enhancer that helps drug penetration. The enteric coat of the core was shellac (SH) with plasticizer glycerol tristearate (GTS) and CA that was applied by direct compression (dry coating). The solventless heat curable coat resulted in an enteric-coated tablet that complies with the USP pharmacopeia. The optimized formula was further subjected to in vitro release and stability studies, as well as ingredient compatibility. In vivo oral bioavailability of the enteric-coated tablets in rabbits gave promising results (absolute bioavailability of about 80%). Synergistically, all ingredients together augmented oral bioavailability of CTX. This developed formula could be a perspective delivery system for those drugs intended to be absorbed from the colon such as peptides and peptide-like drugs.

Appliance of fungal chitosan/ceftriaxone nano-composite to strengthen and sustain their antimicrobial potentiality against drug resistant bacteria

Nano-biopolymers could be employed for the delivery of active compounds to increase their stability, bioavailability, efficacy and sustainability. The bioactive chitosan polymer (Cts) was extracted from grown fungus, Cunninghamella elegans, and used for loading ceftriaxone (CFT) and forming the nano-conjugates using tripolyphosphate (TPP) - ionic crosslinking method. The characterization of synthesized CFT/chitosan nanoparticles (NCT) revealed that they chemically crosslinked and had particles' size mean of 56 nm. The CFT loading capacity onto NCT was 54.37%, while its entrapment efficiency was apparently high (79.43%); the maximum released of CFT was 78% from NCT composite after 90 h from dialysis. The CFT/NCT antibacterial activity was confirmed against 3 strains of Staphylococcus aureus (methicillin resistants), using disc diffusion and scanning images of electron microscope, which elucidate that CFT/NCT nano-composite had a vigorous action toward bacterial cells; most cells were ruptured and exploded after 6 h of exposure and entirely lysed after 9 h. The formulation of CFT/NCT nano-composite is exceedingly recommended for enhancing drug biocidal activity, especially against resistant bacterial strains.

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.

Role of nanostructures in improvising oral medicine

The most preferable mode of drugs administration is via the oral route but physiological barriers such as pH, enzymatic degradation etc. limit the absolute use of this route. Herein lies the importance of nanotechnology having a wide range of applications in the field of nano-medicine, particularly in drug delivery systems. The exclusive properties particularly small size and high surface area (which can be modified as required), exhibited by these nanoparticlesrender these structures more suitable for the purpose of drug delivery. Various nanostructures, like liposomes, dendrimers, mesoporous silica nanoparticles, etc. have been designed for the said purpose. These nanostructures have several advantages over traditional administration of medicine. Apart from overcoming the pharmacokinetic and pharmacodynamics limitations of many potential therapeutic molecules, they may also be useful for advanced drug delivery purposes like targeted drug delivery, controlled release, enhanced permeability and retention (EPR) effect. In this review, we attempt to describe an up-to-date knowledge on various strategically devised nanostructures to overcome the problems related to oral drug administration.

Characterization and study of the antibacterial mechanisms of silver nanoparticles prepared with microalgal exopolysaccharides

The green synthesis of biomaterials is of significant interest as it enables the safe and sustainable preparation of noble metallic nanoparticles for medical applications. Microalgae polysaccharides have received attention due to their outstanding properties such as biocompatibility, biodegradability and low cost. In addition, due to their variety of remarkable biological and physicochemical properties, polysaccharide-based nanoparticles have advantageous features yet to be explored. The primary objective of the current research was to investigate exopolysaccharides isolated from green microalgae Botryococcus braunii (EPBb) and Chlorella pyrenoidosa (EPCp), as both reducing and stabilizing agents, for the green synthesis of silver nanoparticles (AgNPs). Their antibacterial activity towards Gram-positive bacteria (Staphylococcus aureus), Gram-negative bacteria (Escherichia coli), and antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus) was studied, as well as their cytotoxicity to human dermal fibroblasts. The presently synthesized AgNPs were spherical in shape and exhibited characteristic surface plasmon resonance at 430 nm. The main population had a particle size which ranged between 5 and 15 nm as analyzed by transmission electron micrographs. Zeta potentials averaged -51.81 ± 3.01 mV using EPBb and -12.16 ± 2.41 mV using EPCp. More importantly, AgNPs possessed strong antibacterial activity in a dose-dependent manner, even against drug-resistant bacteria. The enhanced antibacterial activity of these particles is explained due to extensive reactive oxygen species generation and bacterial cell membrane damage. In contrast, such AgNPs were not cytotoxic at the same therapeutic range to fibroblasts (0.5-10.0 μg/mL). In summary, these results showed that polysaccharide-capped AgNPs have a strong potential for numerous medical applications, such as antibacterial agents in pharmaceutical and biomedical areas.

Exploring chitosan nanoparticles as effective inhibitors of antibiotic resistant skin microorganisms - From in vitro to ex vitro testing

Nowadays, nosocomial skin infections are increasingly harder to manage and control. In the search for new, natural compounds capable of being alternatives to traditional antibiotics, chitosan and its nanoparticles, have garnered attention. This work sought to understand the potential of chitosan NPs in the management of infections caused by MDR skin pathogens in planktonic and sessile assays. Additionally, NPs' capacity to inhibit biofilm quorum sensing and prevent HaCat infections was also evaluated. The results obtained showed that chitosan NPs had an average size and charge of 226.6 ± 5.24 nm and +27.1 ± 3.09 mV. Inhibitory and bactericidal concentrations varied between 1 and 2 mg/mL and 2-7 mg/mL, respectively. Chitosan NPs effectively inhibited biofilm growth for all microorganisms and possessed strong anti-quorum sensing activity. Lastly, chitosan NPs proved to be effective interfere with A. baumannii's infection of HaCat cells, as they significantly reduced intracellular and extracellular bacterial counts.

Chitosan-based nanosystems and their exploited antimicrobial activity

Chitosan is a biodegradable and biocompatible natural polysaccharide that has a wide range of applications in the field of pharmaceutics, biomedical, chemical, cosmetics, textile and food industry. One of the most interesting characteristics of chitosan is its antibacterial and antifungal activity, and together with its excellent safety profile in human, it has attracted considerable attention in various research disciplines. The antimicrobial activity of chitosan is dependent on a number of factors, including its molecular weight, degree of deacetylation, degree of substitution, physical form, as well as structural properties of the cell wall of the target microorganisms. While the sole use of chitosan may not be sufficient to produce an adequate antimicrobial effect to fulfil different purposes, the incorporation of this biopolymer with other active substances such as drugs, metals and natural compounds in nanosystems is a commonly employed strategy to enhance its antimicrobial potential. In this review, we aim to provide an overview on the different approaches that exploit the antimicrobial activity of chitosan-based nanosystems and their applications, and highlight the latest advances in this field.

Efficacy and safety concerns over the use of mucus modulating agents for drug delivery using nanoscale systems

Drug delivery to the mucus covered mucosae is fraught with difficulties and many different approaches have been developed to permeate the mucus barrier. Generally by modifying the delivery system to avoid interaction with the mucus. These modifications are reviewed here in terms of efficacy and safety. These are particular problems for oral delivery the pharmaceutical industry's favoured route for drug administration. For effective delivery through the gastrointestinal tract a drug must pass through three barriers in sufficient amounts to yield a biological effect. These barriers are the digestive barrier in the lumen, the mucus barrier, and the epithelial barrier. Other approaches involve mucolytic agents added with or prior to the delivery system or agents regulating mucus production and are reviewed here. In terms of safety, a key property of a mucus modulating delivery system is that it must not damage the protective function of the mucus layer.

Synthesis and Characterization of Fatty Acid Grafted Chitosan Polymer and Their Nanomicelles for Nonviral Gene Delivery Applications

The aim of this study was to synthesize and characterize fatty acid-grafted-chitosan (fatty acid-g-CS) polymer and their nanomicelles for use as carriers for gene delivery. CS was hydrophobically modified using saturated fatty acids of increasing fatty acyl chain length. Carbodiimide along with N-hydroxysuccinimide was used for coupling carboxyl group of fatty acids with amine groups of CS. Proton nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to quantify fatty acyl substitution onto CS backbone. The molecular weight distribution of the synthesized polymers was determined using size exclusion high performance liquid chromatography and was found to be in range of the parent CS polymer (∼50 kDa). The critical micelle concentration (cmc) of the polymers was determined using pyrene as a fluorescent probe. The cmc was found to decrease with an increase in fatty acyl chain length. The amphiphilic fatty acid-g-CS polymers self-assembled in an aqueous environment to form nanomicelles of ∼200 nm particle size and slightly positive net charge due to the cationic nature of free primary amino groups on CS molecule. These polymeric nanomicelles exhibited excellent hemo- and cytocompatibility, as evaluated by in vitro hemolysis and MTT cell viability assay, respectively, and showed superior transfection efficiency compared to unmodified chitosan and naked DNA. The surface of these nanomicelles can be further modified with ligands allowing for selective targeting, enhanced cell binding, and internalization. These nanomicelles can thus be exploited as potential nonviral gene delivery vectors for safe and efficient gene therapy.