Genipin-cross-linked fucose-chitosan/heparin nanoparticles for the eradication of Helicobacter pylori

Microparticles and nanoparticles-based approaches to improve oral treatment of Helicobacter pylori infection

Helicobacter pylori is a gram-negative, spiral-shaped, flagellated bacterium that colonizes the stomach of half the world's population. Helicobacter pylori infection causes pathologies of varying severity. Standard oral therapy fails in 15-20% since the barriers of the oral route decrease the bioavailability of antibiotics and the intrinsic factors of bacteria increase the rates of resistance. Nanoparticles and microparticles are promising strategies for drug delivery into the gastric mucosa and targeting H. pylori. The variety of building blocks creates systems with distinct colloidal, surface, and biological properties. These features improve drug-pathogen interactions, eliminate drug depletion and overuse, and enable the association of multiple actives combating H. pylori on several fronts. Nanoparticles and microparticles are successfully used to overcome the barriers of the oral route, physicochemical inconveniences, and lack of selectivity of current therapy. They have proven efficient in employing promising anti-H. pylori compounds whose limitation is oral route instability, such as some antibiotics and natural products. However, the current challenge is the applicability of these strategies in clinical practice. For this reason, strategies employing a rational design are necessary, including in the development of nano- and microsystems for the oral route.

Targeted nanotherapeutics for the treatment of Helicobacter pylori infection

Helicobacter pylori infection is involved in gastric diseases such as peptic ulcer and adenocarcinoma. Approved antibiotherapies still fail in 10 to 40% of the infected patients and, in this scenario, targeted nanotherapeutics emerged as powerful allies for H. pylori eradication. Nano/microparticles conjugated with H. pylori binding molecules were developed to eliminate H. pylori by either (i) blocking essential mechanisms of infection, such as adhesion to gastric mucosa or (ii) binding and killing H. pylori through the release of drugs within the bacteria or at the site of infection. Glycan antigens (as Lewis B and sialyl-Lewis X), pectins, lectins, phosphatidylethanolamine and epithelial cell membranes were conjugated with nano/microparticles to successfully block H. pylori adhesion. Urea-coated nanoparticles were used to improve drug delivery inside bacteria through H. pylori UreI channel. Moreover, nanoparticles coated with antibodies against H. pylori and loaded with sono/photosensitizers, were promising for their application as targeted sono/photodynamic therapies. Further, non-specific H. pylori nano/microparticles, but only active in the acidic gastric environment, coated with binders to bacterial membrane, extracellular polymeric substances or to high temperature requirement A protease, were evaluated. In this review, an overview of the existing nanotherapeutics targeting H. pylori will be given and their rational, potential to counteract infection, as well as level of development will be presented and discussed.

Mucus and Biofilm Penetrating Nanoplatform as an Ultrasound-Induced Free Radical Initiator for Targeted Treatment of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) infection is closely associated with the development of various gastric diseases. The effectiveness of current clinical antibiotic therapy is hampered by the rise of drug-resistant strains and the formation of H. pylori biofilm. This paper reports a sonodynamic nanocomposite PtCu3-PDA@AIPH@Fucoidan (PPAF), which consists of dopamine-modified inorganic sonosensitizers PtCu3, alkyl radicals (R•) generator AIPH and fucoidan, can penetrate the mucus layer, target H. pylori, disrupt biofilms, and exhibit excellent bactericidal ability. In vitro experiments demonstrate that PPAF exhibits excellent acoustic kinetic properties, generating a significant amount of reactive oxygen species and oxygen-independent R• for sterilization under ultrasound stimulation. Simultaneously, the produced N2 can enhance the cavitation effect, aiding PPAF nanoparticles in penetrating the gastric mucus layer and disrupting biofilm integrity. This disruption allows more PPAF nanoparticles to bind to biofilm bacteria, facilitating the eradication of H. pylori. In vivo experiments demonstrate that ultrasound-stimulated PPAF exhibited significant antibacterial efficacy against H. pylori. Moreover, it effectively modulated the expression levels of inflammatory factors and maintained gastrointestinal microbiota stability when compared to the antibiotic treatment group. In summary, PPAF nanoparticles present a potential alternative to antibiotics, offering an effective and healthy option for treating H. pylori infection.

An antibiotic-free platform for eliminating persistent Helicobacter pylori infection without disrupting gut microbiota

Helicobacter pylori (H. pylori) infection remains the leading cause of gastric adenocarcinoma, and its eradication primarily relies on the prolonged and intensive use of two antibiotics. However, antibiotic resistance has become a compelling health issue, leading to H. pylori eradication treatment failure worldwide. Additionally, the powerlessness of antibiotics against biofilms, as well as intracellular H. pylori and the long-term damage of antibiotics to the intestinal microbiota, have also created an urgent demand for antibiotic-free approaches. Herein, we describe an antibiotic-free, multifunctional copper-organic framework (HKUST-1) platform encased in a lipid layer comprising phosphatidic acid (PA), rhamnolipid (RHL), and cholesterol (CHOL), enveloped in chitosan (CS), and loaded in an ascorbyl palmitate (AP) hydrogel: AP@CS@Lip@HKUST-1. This platform targets inflammatory sites where H. pylori aggregates through electrostatic attraction. Then, hydrolysis by matrix metalloproteinases (MMPs) releases CS-encased nanoparticles, disrupting bacterial urease activity and membrane integrity. Additionally, RHL disperses biofilms, while PA promotes lysosomal acidification and activates host autophagy, enabling clearance of intracellular H. pylori. Furthermore, AP@CS@Lip@HKUST-1 alleviates inflammation and enhances mucosal repair through delayed Cu2+ release while preserving the intestinal microbiota. Collectively, this platform presents an advanced therapeutic strategy for eradicating persistent H. pylori infection without inducing drug resistance.

Engineering resveratrol-loaded chitosan nanoparticles for potential use against Helicobacter pylori infection

Helicobacter pylori (H. pylori) is a microorganism directly linked to severe clinical conditions affecting the stomach. The virulence factors and its ability to form biofilms increase resistance to conventional antibiotics, growing the need for new substances and strategies for the treatment of H. pylori infection. The trans-resveratrol (RESV), a bioactive polyphenol from natural sources, has a potential activity against this gastric pathogen. Here, Chitosan nanoparticles (NP) containing RESV (RESV-NP) were developed for H. pylori management. The RESV-NP were prepared using the ionic gelation method and characterized by Dynamic Light Scattering (DLS), Nanoparticle Tracking Analysis (NTA) and, Cryogenic Transmission Electron Microscopy (Cryo - TEM). The encapsulation efficiency (EE) and in vitro release rate of RESV were quantified using high-performance liquid chromatography (HPLC). RESV-NP performance against H. pylori was evaluated by the quantification of the minimum inhibitory/bactericidal concentrations (MIC/MBC), time to kill, alterations in H. pylori morphology in its planktonic form, effects against H. pylori biofilm and in an in vitro infection model. RESV-NP cytotoxicity was evaluated against AGS and MKN-74 cell lines and by hemolysis assay. Acute toxicity was tested using Galleria mellonella model assays. RESV-NP showed a spherical shape, size of 145.3 ± 24.7 nm, polydispersity index (PDI) of 0.28 ± 0.008, and zeta potential (ZP) of + 16.9 ± 1.81 mV in DLS, while particle concentration was 3.12 x 1011 NP/mL (NTA). RESV-NP EE was 72 %, with full release within the first 5 min. In microbiological assays, RESV-NP presented a MIC/MBC of 3.9 µg/mL, a time to kill of 24 h for complete eradication of H. pylori. At a concentration of 2xMIC (7.8 µg/mL), RESV-NP completely eradicated the H. pylori biofilm, and in an in vitro infection model, RESV-NP (4xMIC - 15.6 µg/mL) showed a significant decrease in bacterial load (1 Log10CFU/mL) when compared to the H. pylori J99 control. In addition, they did not demonstrate a toxic character at MIC concentration for both cell lines. The use of the RESV-NP with mucoadhesion profile is an interesting strategy for oral administration of substances targeting gastric disorders, linked to H. pylori infections.

Future Nanotechnology-Based Strategies for Improved Management of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a recalcitrant pathogen, which can cause gastric disorders. During the past decades, polypharmacy-based regimens, such as triple and quadruple therapies have been widely used against H. pylori. However, polyantibiotic therapies can disturb the host gastric/gut microbiota and lead to antibiotic resistance. Thus, simpler but more effective approaches should be developed. Here, some recent advances in nanostructured drug delivery systems to treat H. pylori infection are summarized. Also, for the first time, a drug release paradigm is proposed to prevent H. pylori antibiotic resistance along with an IVIVC model in order to connect the drug release profile with a reduction in bacterial colony counts. Then, local delivery systems including mucoadhesive, mucopenetrating, and cytoadhesive nanobiomaterials are discussed in the battle against H. pylori infection. Afterward, engineered delivery platforms including polymer-coated nanoemulsions and polymer-coated nanoliposomes are poposed. These bioinspired platforms can contain an antimicrobial agent enclosed within smart multifunctional nanoformulations. These bioplatforms can prevent the development of antibiotic resistance, as well as specifically killing H. pylori with no or only slight negative effects on the host gastrointestinal microbiota. Finally, the essential checkpoints that should be passed to confirm the potential effectiveness of anti-H. pylori nanosystems are discussed.

The Advancement and Obstacles in Improving the Stability of Nanocarriers for Precision Drug Delivery in the Field of Nanomedicine

Nanocarriers have emerged as a promising class of nanoscale materials in the fields of drug delivery and biomedical applications. Their unique properties, such as high surface area- tovolume ratios and enhanced permeability and retention effects, enable targeted delivery of therapeutic agents to specific tissues or cells. However, the inherent instability of nanocarriers poses significant challenges to their successful application. This review highlights the importance of nanocarrier stability in biomedical applications and its impact on biocompatibility, targeted drug delivery, long shelf life, drug delivery performance, therapeutic efficacy, reduced side effects, prolonged circulation time, and targeted delivery. Enhancing nanocarrier stability requires careful design, engineering, and optimization of physical and chemical parameters. Various strategies and cutting-edge techniques employed to improve nanocarrier stability are explored, with a focus on their applications in drug delivery. By understanding the advances and challenges in nanocarrier stability, this review aims to contribute to the development and implementation of nanocarrier- based therapies in clinical settings, advancing the field of nanomedicine.

Stimulus-responsive biomaterials for Helicobacter pylori eradication

BACKGROUND

Helicobacter pylori (H. pylori), the only bacterium classified as a type I (definite) carcinogen, is strongly associated with the development of gastric inflammation and adenocarcinoma. It infects the stomach of approximately half of the global population, equivalent to nearly 4.4 billion people. However, due to physiological barriers in the stomach, microbial barriers and increased antibiotic resistance, the therapeutic efficiency of standard antibiotic therapy is limited and cannot meet the clinical needs in some areas. Combining stimulus-responsive biomaterials with certain stimuli is an emerging antibacterial strategy. Stimulus-responsive biomaterials can respond to chemical, biological or physical cues in the environment with corresponding changes in their own properties and functions, highlighting a more intelligent, targeting and efficient aspect for H. pylori therapy.

AIM OF REVIEW

This review describes the critical obstacles in the current treatment of H. pylori, summarizes the recent advances in stimulus-responsive biomaterials against H. pylori by elucidating their working mechanisms and antibacterial performances under different types of stimuli (pH, enzymes, light, magnetic and ultrasound irradiations), and attempts to analyze the future prospects of such smart biomaterial for H. pylori eradication. Key Scientific Concepts of Review: Any characteristic property or change in the biomilieu at the H. pylori infected site (endogenous stimuli) or specific iatrogenic conditions in vitro (exogenous stimuli) can act as cues to activate or potentiate the antibacterial activity of responsive biomaterials. The responsiveness of these materials to endogenous stimuli enhances antimicrobial targeting, and makes physiological barriers that would otherwise hinder conventional H. pylori therapies a key factor in facilitating antibacterial effects. The responsiveness to exogenous stimuli greatly prolongs the action time of antimicrobial materials and pinpoints the site of infection, thereby reducing toxic side effects. These findings pave the way for the development of more precise and effective anti-H. pylori treatment.

Treatment of H. pylori infection and gastric ulcer: Need for novel Pharmaceutical formulation

Peptic ulcer disease (PUD) is one of the most prevalent gastro intestinal disorder which often leads to painful sores in the stomach lining and intestinal bleeding. Untreated Helicobacter pylori (H. pylori) infection is one of the major reasons for chronic PUD which, if left untreated, may also result in gastric cancer. Treatment of H. pylori is always a challenge to the treating doctor because of the poor bioavailability of the drug at the inner layers of gastric mucosa where the bacteria resides. This results in ineffective therapy and antibiotic resistance. Current treatment regimens available for gastric ulcer and H. pylori infection uses a combination of multiple antimicrobial agents, proton pump inhibitors (PPIs), H2-receptor antagonists, dual therapy, triple therapy, quadruple therapy and sequential therapy. This polypharmacy approach leads to patient noncompliance during long term therapy. Management of H. pylori induced gastric ulcer is a burning issue that necessitates alternative treatment options. Novel formulation strategies such as extended-release gastro retentive drug delivery systems (GRDDS) and nanoformulations have the potential to overcome the current bioavailability challenges. This review discusses the current status of H. pylori treatment, their limitations and the formulation strategies to overcome these shortcomings. Authors propose here an innovative strategy to improve the H. pylori eradication efficiency.

Extracellular matrix component-derived nanoparticles for drug delivery and tissue engineering

The extracellular matrix (ECM) consists of a complex combination of proteins, proteoglycans, and other biomolecules. ECM-based materials have been demonstrated to have high biocompatibility and bioactivity, which may be harnessed for drug delivery and tissue engineering applications. Herein, nanoparticles incorporating ECM-based materials and their applications in drug delivery and tissue engineering are reviewed. Proteins such as gelatin, collagen, and fibrin as well as glycosaminoglycans including hyaluronic acid, chondroitin sulfate, and heparin have been employed for cancer therapeutic delivery, gene delivery, and wound healing and regenerative medicine. Strategies for modifying and functionalizing these materials with synthetic and natural polymers or to enable stimuli-responsive degradation and drug release have increased the efficacy of these materials and nano-systems. The incorporation and modification of ECM-based materials may be used to drive drug targeting and increase tissue-specific cell differentiation more effectively.

Retention Time Extended by Nanoparticles Improves the Eradication of Highly Antibiotic-Resistant Helicobacter pylori

Helicobacter pylori infection usually causes gastrointestinal complications, including gastrointestinal bleeding or perforation, and serious infections may lead to gastric cancer. Amoxicillin is used to treat numerous bacterial infections but is easily decomposed in the gastric acid environment via the hydrolyzation of the β-lactam ring. In this study, we develop chitosan-based nanoparticles loaded with amoxicillin (CAANs) as an H. pylori eradication platform. The CAANs were biocompatible and could retain the antibiotic activity of amoxicillin against H. pylori growth. The mucoadhesive property of chitosan and alginate enabled the CAANs to adhere to the mucus layers and penetrate through these to release amoxicillin in the space between the layers and the gastric epithelium. The use of this nanoparticle could prolong the retention time and preserve the antibiotic activity of amoxicillin in the stomach and help enhance the eradication rate of H. pylori and reduce treatment time. These CAANs, therefore, show potential for the effective treatment of highly antibiotic-resistant H. pylori infection using amoxicillin.

Hydrogels as promising carriers for the delivery of food bioactive ingredients

The burden of public health challenges associated with the western dietary and living style is growing. Nutraceuticals have been paid increasing attentions due to their effects in promotion of health. However, in the gastrointestinal (GI) tract, the nutraceuticals suffer from not only the harsh acidic environment of the stomach and a variety of digestive enzymes, but also the antibacterial activity of intestinal bile salts and the action of protease from the gut microbiota. The amount of the nutraceuticals arriving at the sites in GI tract for absorption or exerting the bioactivities is always unfortunately limited, which puts forward high requirements for protection of nutraceuticals in a certain high contents during oral consumption. Hydrogels are three-dimensional polymeric porous networks formed by the cross-linking of polymer chains, which can hold huge amounts of water. Compared with other carries with the size in microscopic scale such as nanoparticle and microcapsules, hydrogels could be considered to be more suitable delivery systems in food due to their macroscopic bulk properties, adjustable viscoelasticity and large spatial structure for embedding nutraceuticals. Regarding to the applications in food, natural polymer-based hydrogels are commonly safe and popular due to their source with the appealing characteristics of affordability, biodegradability and biocompatibility. Although chemical crosslinking has been widely utilized in preparation of hydrogels, it prefers the physical crosslinking in the researches in food. The reasonable design for the structure of natural polymeric hydrogels is essential for seeking the favorable functionalities to apply in the delivery system, and it could be possible to obtain the enhanced adhesive property, acid stability, resistant to bile salt, and the controlled release behavior. The hydrogels prepared with proteins, polysaccharides or the mix of them to deliver the functional ingredients, mainly the phenolic components, vitamins, probiotics are discussed to obtain inspiration for the wide applications in delivery systems. Further efforts might be made in the in situ formation of hydrogels in GI tract through the interaction among food polymers and small-molecular ingredients, elevation of the loading contents of nutraceuticals in hydrogels, development of stomach adhesive hydrogels as well as targeting modification of gut microbiota by the hydrogels.

Biomaterials for Helicobacter pylori therapy: therapeutic potential and future perspectives

Helicobacter pylori (H. pylori) is the main cause of gastric adenocarcinoma. However, the traditional antibiotic treatment of H. pylori is limited due to increased antibiotic resistance and low efficacy; low drug delivery efficiency and difficulties in eradicating H. pylori that is present intracellularly or in biofilms cause further setbacks. Biomaterials that can protect drugs against stomach acid, target lesions, control drug release, destroy biofilms, and exhibit unique antibacterial mechanisms and excellent biocompatibility have emerged as attractive tools for H. pylori eradication, particularly for drug-resistant strains. Herein, we review the virulence mechanisms, current drug treatments, and antibiotic resistance of H. pylori strains. Furthermore, recent advances in the development of biomaterials, including nanoparticles (such as lipid-based nanoparticles, polymeric nanoparticles, and inorganic nanoparticles), microspheres, and hydrogels, for effective and precise therapy of H. pylori and different types of therapeutic mechanisms, as well as future perspectives, have also been summarized.

Understanding of physicochemical properties and antioxidant activity of ovalbumin-sodium alginate composite nanoparticle-encapsulated kaempferol/tannin acid

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare an OVA–SA composite carrier, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA). Results showed that the observation of small diffraction peaks in carriers proved the successful encapsulation of KAE/TA. The protein conformation of the composite nanoparticles changed. OVA–TA–SA composite nanoparticles had the highest α-helix content and the fewest random coils, so the protein structure of it had the strongest stability. OVA–TA–KAE–SA composite nanoparticles had the strongest system stability and thermal stability, which might be due to the synergistic effect of the two polyphenols, suggesting the encapsulation of KAE/TA increased the system stability and the thermal stability of OVA–SA composite nanoparticles. Additionally, the composite nanoparticles were endowed with antioxidant ability and antibacterial ability (against Staphylococcus aureus and Escherichia coli) in the order OVA–TA–SA > OVA–TA–KAE–SA > OVA–KAE–SA based on the difference in antibacterial diameter (D, mm) and square (S, mm²), indicating that polyphenols enhanced the antibacterial and antioxidant ability of OVA–SA composite nanoparticles, and the enhancement effect of TA was stronger than that of KAE. These results provide a theoretical basis for the application of OVA–SA composite nanoparticles in the delivery of bioactive compounds.

Ovalbumin (OVA) and sodium alginate (SA) were used as materials to prepare an OVA–SA composite carrier, which encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA).

Influence of polyphenol-metal ion-coated ovalbumin/sodium alginate composite nanoparticles on the encapsulation of kaempferol/tannin acid

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare OVA-SA composite carriers, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA). To achieve the purpose of targeted delivery, the TA-Fe³⁺ coating film was prepared. Results showed that the observation of small diffraction peaks in carriers proved the formation of TA/Fe³⁺ coating film on the surface of four composite nanoparticles (pOVA, pOVA-SA, pOVA-KAE-SA, and pOVA-KAE-TA-SA). The protein structure of the composite nanoparticles coated with TA/Fe³⁺ changed, and the order of the changes was pOVA-KAE > pOVA > pOVA-KAE-SA > pOVA-KAE-TA-SA > pOVA-SA. This phenomenon is due to the fact that the chromophore -C=O and the auxo-chromophore -OH are in the opposite position in the benzene ring of TA, and the two substituents have opposite effects and synergize, resulting in the different degrees of redshift of the composite nanoparticle λ_max. Additionally, pOVA-SA had the highest α-helix content and the lowest random coils, conferring the protein structure the strongest stability. The coating of TA/Fe³⁺ increased the system stability and the thermal stability of the composite nanoparticles. Additionally, the carriers were endowed with antioxidant activity, and their antibacterial ability against Staphylococcus aureus and Escherichia coli was pOVA-KAE-TA-SA > pOVA-KAE-SA > pOVA-KAE > pOVA-SA > pOVA based on the difference in antibacterial diameter (D, mm) and square (S, mm²). pOVA-KAE-TA-SA had the strongest antioxidant activity and antibacterial ability, which improved the bioavailability of TA/KAE. These results provide a theoretical basis for the application of OVA-SA composite nanoparticles in the delivery of bioactive compounds.

Recent Developments in Drug Delivery for Treatment of Tuberculosis by Targeting Macrophages

Tuberculosis (TB) is among the greatest public health and safety concerns in the 21st century, Mycobacterium tuberculosis, which causes TB, infects alveolar macrophages and uses these cells as one of its primary sites of replication. The current TB treatment regimen, which consist of chemotherapy involving a combination of 3-4 antimicrobials for a duration of 6-12 months, is marked with significant side effects, toxicity, and poor compliance. Targeted drug delivery offers a strategy that could overcome many of the problems of current TB treatment by specifically targeting infected macrophages. Recent advances in nanotechnology and material science have opened an avenue to explore drug carriers that actively and passively target macrophages. This approach can increase the drug penetration into macrophages by using ligands on the nanocarrier that interact with specific receptors for macrophages. This review encompasses the recent development of drug carriers specifically targeting macrophages actively and passively. Future directions and challenges associated with development of effective TB treatment is also discussed.

Novel naltrexone hydrochloride nanovaccine based on chitosan nanoparticles promotes induction of Th1 and Th17 immune responses resulting in protection against Toxoplasma gondii tachyzoites in a mouse model

This study was aimed to encapsulate and construct the Toxoplasma gondii surface antigen (SAG1) and naltrexone hydrochloride (NLT-HCL) as an adjuvant within chitosan nanoparticles (CS-NPs) to develop efficacious vaccine against T. gondii. Seven groups of BALB/c mice were immunized with SAG1, chitosan (CS), NLT-SAG1, CS-SAG1, CS-SAG1-NLT, CS-NLT and PBS. The efficiency of each approach was detected in vivo mouse immunization. Moreover, the immuno-induction effect of SAG1 recombinant protein and CS-NPs-based NLT-HCL as an adjuvant in a vaccine delivery was evaluated. Experimentally, Th1/Th17 biased cellular and humoral immune responses were activated in the mice immunized with CS-SAG1-NLT nanoparticles that were accompanied by considerable increased production of IFN-γ, IL-17, IL-12, IL-4, IFN-γ/IL-4 ratio, IgG, IgG2a. This group of mice also showed significantly increased survival time post-challenging. The successful encapsulated SAG1 recombinant protein and NLT-HCL, as an adjuvant, within CS-NPs can induce immune responses against toxoplasmosis. We could incorporate NLT-HCL adjuvant into the CS-NPs based delivery systems, which makes CS-NPs attractive as a colloidal carrier system for NLT-HCL as secondary adjuvant. This new approach or the simultaneous use of CS and NLT demonstrated that the co-administration of CS-NPs and NLT-HCL induce production of IL-17 cytokine. This approach can be used for vaccination purposes, in which Th17 and Th1 cellular immune are considered the key of the successful immune response.

Chitosan-curcumin complexation to develop functionalized nanosystems with enhanced antimicrobial activity against hetero-resistant gastric pathogen

With the apparent stagnation in the antibiotic discovery and the propagation of multidrug resistance, Helicobacter pylori associated gastric infections are hard to eradicate. In pursuance of alternative medicines, in this study, covalent modification of chitosan (CS) polymer with curcumin (Cur) was accomplished. Proton Nuclear Magnetic Resonance and Fourier Transform Infrared spectroscopy elucidated the covalent interaction between Cur and CS with characteristic peak of imine functional group (C=N). Scanning Electron Microscopy provided visual proof for surface topology, while size and zeta potential values further affirmed the development of curcumin functionalized chitosan nanosystems (Cur-FCNS). The complexation efficiency of CS with Cur was found as 70 ± 3% at an optimal ratio of 5:1 for CS and Cur, respectively. Cur-FCNS developed with ionic gelation and ultrasonication method demonstrated synergistic anti-H. pylori activity in growth-kinetics and anti-biofilm assays, which was superior to free Cur and even chitosan nanosystems. Under simulated gastric conditions, Cur-FCNS revealed cumulative-release of only 16 ± 0.8% till 40 h, which indicated its improved stability to interact with H. pylori. In silico findings affirmed high binding affinity of Cur-FCNS with multiple bacterial virulence factors. Thus, our results affirmed the exceptional potential of Cur-FCNS as next-generation alternative-medicine to treat resistant H. pylori.

Taking leads out of nature, can nano deliver us from COVID-like pandemics?

The COVID-19 crisis has alerted the research community to re-purpose scientific tools that can effectively manage emergency pandemic situations. Researchers were never so desperate to discover a 'magic bullet' that has significant clinical benefits with minimal or no side effects. At the beginning of the pandemic, due to restricted access to traditional laboratory techniques, many research groups delved into computational screening of thousands of lead molecules that could inhibit SARS-CoV-2 at one or more stages of its infectious cycle. Several in silico studies on natural derivatives point out their potency against SARS-CoV-2 proteins. However, theoretical predictions and existing knowledge on related molecules reflect their poor oral bioavailability due to biotransformation in the gut and liver. Nanotechnology has evolved into a key field for precise and controlled delivery of various drugs that lack aqueous solubility, have low oral bioavailability and possess pronounced toxicity in their native form. In this review, we discuss various nanoformulations of natural products with favorable ADME properties, and also briefly explore nano-drug delivery to lungs, the primary site of SARS-CoV-2 infection. Natural products are also envisioned to augment nanotechnology-based 1) personnel protective equipment for ex vivo viral inactivation and 2) wearable sensors that perform rapid and non-invasive analysis of volatile organic compounds in exhaled breath of the infected person after therapeutic food consumption.

Combatting Helicobacter pylori with oral nanomedicines

Helicobacter pylori (H. pylori) infection is considered to be the main cause of most digestive diseases,such as chronic active gastritis, gastroduodenal ulcers, or even gastric cancer. Oral medication is a transformative approach to treat H. pylori-induced infections. However, unlike intravenous administration, orally administrated drugs have to overcome various barriers before reaching the infected sites, which significantly limits the therapeutic efficacy. These challenges may be addressed by emerging nanomedicine that is equipped with nanotechnology approaches to enable efficient and effective targeted delivery of drugs. Herein, in this review, we first discuss the conventional therapy for the eradication of H. pylori. Through the introduction of the critical barriers of oral administration, the benefits of nanomedicine are highlighted. Recently-published examples of nanocarriers for combating H. pylori in terms of design, preparation, and antimicrobial mechanisms are then presented, followed by our perspective on potential future research directions of oral nanomedicines.

Fucoidan-Coated Liposomes: A Target System to Deliver the Antimicrobial Drug Usnic Acid to Macrophages Infected with Mycobacterium tuberculosis

The present study describes the use of fucoidan, a negative sulfated polysaccharide, as a coating material for the development of liposomes targeted to macrophages infected with Mycobacterium tuberculosis. First, fucoidan was chemically modified to obtain a hydrophobized-fucoidan derivative (cholesteryl-fucoidan) using a two-step microwave-assisted (μW) method. The total reaction time was decreased from 14 hours to 1 hour while maintaining the overall yield. Cholesterylfucoidan was then used to prepare surface-modified liposomes containing usnic acid (UA-LipoFuc), an antimicrobial lichen derivative. UA-LipoFuc was evaluated for mean particle size, polydispersity index (PDI), surface charge (ζ), and UA encapsulation efficiency. In addition, a cytotoxicity study, competition assay and an evaluation of antimycobacterial activity against macrophages infected with M. tuberculosis (H37Ra) were performed. When the amount of fucoidan was increased (from 5 to 20 mg), vesicle size increased (from 168 ± 2.82 nm to 1.18 ± 0.01 μm). Changes in from +20 ± 0.41 mV for uncoated liposomes to -5.41 ± 0.23 mV for UA-LipoFuc suggested that the fucoidan was placed on the surface of the liposomes. UA-LipoFuc exhibited a lower IC⁵⁰ (8.26 ± 1.11 μM) than uncoated liposomes (18.37 ± 3.34 μM), probably due to its higher uptake. UA-LipoFuc₅ was internalized through the C-type carbohydrate recognition domain of the cell membrane. Finally, usnic acid, both in its free form and encapsulated in fucoidan-coated liposomes (UA-LipoFuc₅), was effective against infected macrophages. Hence, this preliminary investigation suggests that encapsulated usnic acid will aid in further studies related to infected macrophages and may be a potential option for tuberculosis treatment.

Nanochitosan: Commemorating the Metamorphosis of an ExoSkeletal Waste to a Versatile Nutraceutical

Chitin (poly-N-acetyl-D-glucosamine) is the second (after cellulose) most abundant organic polymer. In its deacetylated form-chitosan-becomes a very interesting material for medical use. The chitosan nano-structures whose preparation is described in this article shows unique biomedical value. The preparation of nanochitosan, as well as the most vital biomedical applications (antitumor, drug delivery and other medical uses), have been discussed in this review. The challenges confronting the progress of nanochitosan from benchtop to bedside clinical settings have been evaluated. The need for inclusion of nano aspects into chitosan research, with improvisation from nanotechnological inputs has been prescribed for breaking down the limitations. Future perspectives of nanochitosan and the challenges facing nanochitosan applications and the areas needing research focus have been highlighted.

Highlighting the use of micro and nanoparticles based-drug delivery systems for the treatment of Helicobacter pylori infections

Due to the high adaptability of Helicobacter pylori and the low targeting specificity of the drugs normally used in pharmacological therapy, the strains are becoming increasingly resistant to these drugs, making it difficult to eradicate the infection. Thus, the search for new therapeutic approaches has been considered urgent. The incorporation of drugs in advanced drug delivery systems, such as nano and microparticles, would allow the improvement of the retention time in the stomach and the prolongation of drug release rates at the target site. Because of this, the present review article aims to highlight the use of micro and nanoparticles as important technological tools for the treatment of H. pylori infections, focussing on the main nanotechnological systems, including nanostructured lipid carriers, liposomes, nanoemulsion, metallic nanoparticles, and polymeric nanoparticles, as well as microtechnological systems such as gastroretentive dosage forms, among them mucoadhesive, magnetic and floating systems were highlighted.

Modulation Effects of Toxoplasma gondii Histone H2A1 on Murine Macrophages and Encapsulation with Polymer as a Vaccine Candidate

Toxoplasma gondii (T. gondii) is the most common zoonotic protozoa and has infected about one-third of the population worldwide. Recombinant epitopes encapsulated in nanospheres have advantages over traditional T. gondii vaccines. For an efficient delivery system, poly (DL-lactide-co-glycolide) (PLGA) and chitosan are the most frequently used biodegradable polymeric nanospheres with strong safety profiles. In the present study, we first expressed and purified histone H2A1 of T. gondii using the prokaryotic expression system. The effects of recombinant TgH2A1 on the functions of murine macrophages were then studied. Purified recombinant TgH2A1 was then encapsulated in nanospheres with PLGA and chitosan. After subcutaneous vaccination in mice, the immune response was evaluated by double antibody sandwich ELISA kits. The results from this study showed that PLGA and chitosan loaded with rTgH2A1 could trigger a stronger Th1 oriented immune response and prolong the survival time of mice effectively. In conclusion, PLGA and chitosan nanospheres loaded with histone H2A1 are an effective method for the development of vaccines against T. gondii. Further studies should focus on evaluating the regulatory mechanism of TgH2A1, vaccine potency, and cellular response in chronic T. gondii infections.

Screening of Bacterial Quorum Sensing Inhibitors in a Vibrio fischeri LuxR-Based Synthetic Fluorescent E. coli Biosensor

A library of 23 pure compounds of varying structural and chemical characteristics was screened for their quorum sensing (QS) inhibition activity using a synthetic fluorescent Escherichia coli biosensor that incorporates a modified version of lux regulon of Vibrio fischeri. Four such compounds exhibited QS inhibition activity without compromising bacterial growth, namely, phenazine carboxylic acid (PCA), 2-heptyl-3-hydroxy-4-quinolone (PQS), 1H-2-methyl-4-quinolone (MOQ) and genipin. When applied at 50 µM, these compounds reduced the QS response of the biosensor to 33.7% ± 2.6%, 43.1% ± 2.7%, 62.2% ± 6.3% and 43.3% ± 1.2%, respectively. A series of compounds only showed activity when tested at higher concentrations. This was the case of caffeine, which, when applied at 1 mM, reduced the QS to 47% ± 4.2%. In turn, capsaicin, caffeic acid phenethyl ester (CAPE), furanone and polygodial exhibited antibacterial activity when applied at 1mM, and reduced the bacterial growth by 12.8% ± 10.1%, 24.4% ± 7.0%, 91.4% ± 7.4% and 97.5% ± 3.8%, respectively. Similarly, we confirmed that trans-cinnamaldehyde and vanillin, when tested at 1 mM, reduced the QS response to 68.3% ± 4.9% and 27.1% ± 7.4%, respectively, though at the expense of concomitantly reducing cell growth by 18.6% ± 2.5% and 16% ± 2.2%, respectively. Two QS natural compounds of Pseudomonas aeruginosa, namely PQS and PCA, and the related, synthetic compounds MOQ, 1H-3-hydroxyl-4-quinolone (HOQ) and 1H-2-methyl-3-hydroxyl-4-quinolone (MHOQ) were used in molecular docking studies with the binding domain of the QS receptor TraR as a target. We offer here a general interpretation of structure-function relationships in this class of compounds that underpins their potential application as alternatives to antibiotics in controlling bacterial virulence.

Orally administrated chitosan microspheres bind Helicobacter pylori and decrease gastric infection in mice

Persistent Helicobacter pylori (H. pylori) infection is related to 90% of gastric cancers. With bacterial resistance rising and treatment inefficiency affecting 15% of the patients, alternative treatments urge. Chitosan microspheres (ChMics) have been proposed as an H. pylori-binding system. This work evaluates ChMics biocompatibility, mucopenetration and capacity to treat H. pylori infection in mice after oral administration. ChMics of different size (XL, ∼120 µm and XS, ∼40 µm) and degree of acetylation (6% and 16%) were developed and revealed to be able to adhere both human and mouse-adapted H. pylori strains without cytotoxicity towards human gastric cells. Ex vivo studies showed that smaller (XS) microspheres penetrate further within the gastric foveolae, suggesting their ability to reach deeply adherent bacteria. In vivo assays showed 88% reduction of infection when H. pylori-infected mice (C57BL/6) were treated with more mucoadhesive XL6 and XS6 ChMics. Overall, ChMics clearly demonstrate ability to reduce H. pylori gastric infection in mice, with chitosan degree of acetylation being a dominant factor over microspheres' size on H. pylori removal efficiency. These results evidence the strong potential of this strategy as an antibiotic-free approach to fight H. pylori infection, where microspheres are orally administered, bind H. pylori in the stomach, and remove them through the gastrointestinal tract. STATEMENT OF SIGNIFICANCE: Approximately 90% of gastric cancers are caused by the carcinogenic agent Helicobacter pylori, which infects >50% of the world population. Bacterial resistance, reduced antibiotic bioavailability, and the intricate distribution of bacteria in mucus and within gastric foveolae hamper the success of most strategies to fight H. pylori. We demonstrate that an antibiotic-free therapy based on bare chitosan microspheres that bind and remove H. pylori from stomach can achieve 88% reduction of infection from H. pylori-infected mice. Changing size and mucoadhesive properties, microspheres can reach different areas of gastric mucosa: smaller and less mucoadhesive can penetrate deeper into the foveolae. This promising, simple and inexpensive strategy paves the way for a faster bench-to-bedside transition, therefore holding great potential for clinical application.

Fullerenol Nanoparticles Eradicate Helicobacter pylori via pH-Responsive Peroxidase Activity

Helicobacter pylori (H. pylori) eradication by antibiotics and proton pump inhibitor treatment is limited by the low pH microenvironment in the stomach and can lead to antibiotic resistance. We fabricated fullerenol nanoparticles (FNPs) with varied chemical structures responding to a pinacol rearrangement of vicinal hydroxyl to form carbonyls in low pH environments. An obvious increase in C═O/C-O was induced in low pH and was positively correlated with a peroxidase-like activity. The FNPs exerted an excellent effect on H. pylori eradication in vitro and in vivo because of their peroxidase-like activity. FNP treatment of a H. pylori biofilm revealed that FNPs broke down polysaccharides in cell wall components, resulting in collapse of the bacteria. The cycles of FNPs combining and dissociating with the peroxidase substrate were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and confirmed that FNPs enhance peroxidase-like activity. Further, the isothermal titration calorimetry results showed that FNPs with more C═O/C-O had greater affinity to bind the peroxidase substrates. Therefore, we suggest that varied C═O/C-O serves as a switch to respond to low pH in the stomach to kill H. pylori by inducing a peroxidase-like activity. FNPs can also overcome the challenge of antibiotic resistance to achieve H. pylori eradication in the stomach.

Covalently and ionically, dually crosslinked chitosan nanoparticles block quorum sensing and affect bacterial cell growth on a cell-density dependent manner

In our efforts to improve the quality and stability of chitosan nanoparticles (NPs), we describe here a new type of chitosan NPs dually crosslinked with genipin and sodium tripolyphosphate (TPP) that display quorum quenching activity. These NPs were created using a simplified and robust procedure that resulted in improved physicochemical properties and enhanced stability. This procedure involves the covalent crosslinking of chitosan with genipin, followed by the formation of chitosan NPs by ionic gelation with TPP. We have optimized the conditions to obtain genipin pre-crosslinked nanoparticles (PC-NPs) with positive ς-potential (~ +30 mV), small diameter (~130 nm), and low size distributions (PdI = 0.1-0.2). PC-NPs present physicochemical properties that are comparable to those of other dually crosslinked chitosan NPs fabricated with different protocols. In contrast to previously characterized NPs, however, we found that PC-NPs strongly reduce the acyl homoserine lactone (AHL)-mediated quorum sensing response of an Escherichia coli fluorescent biosensor. Thus, PC-NPs combine, in a single design, the stability of dually crosslinked chitosan NPs and the quorum quenching activity of ionically crosslinked NPs. Similar to other chitosan NPs, the mode of action of PC-NPs is consistent with the existence of a "stoichiometric ratio" of NP/bacterium, at which the positive charge of the NPs counteracts the negative ς-potential of the bacterial envelope. Notably, we found that the time of the establishment of the "stoichiometric ratio" is a function of the NP concentration, implying that these NPs could be ideal for applications aiming to target of bacterial populations at specific cell densities. We are confident that our PC-NPs are up-and-coming candidates for the design of efficient anti-quorum sensing and a new generation antimicrobial strategies.

Smart drug delivery against Helicobacter pylori: pectin-coated, mucoadhesive liposomes with antiadhesive activity and antibiotic cargo

The first step in the development of Helicobacter pylori pathogenicity is the receptor-mediated adhesion to the gastric epithelium. Inhibition of outer membrane proteins of H. pylori (e.g. BabA) by antiadhesive drugs will contribute to reduced recolonization and infection. Pectin from apple inhibits the BabA and LPS-mediated adhesion of H. pylori to human stomach cells. Pectin-coated liposomes with encapsulated amoxicillin were characterized for polydispersity, zeta potential, encapsulation efficiency, stability, and amoxicillin release. Coated liposomes did not influence the viability of AGS and HT29-MTX cells up to 100 μg/mL but exert cytotoxicity against H. pylori at 10 μg/mL. Pectin-coating of liposomes provoked direct interaction and subsequent binding of the particles to surface structures of H. pylori, and interaction with mucus from porcine stomach and mucus secreted by HT29-MTX cells. Laser scanning microscopy of H. pylori and AGS cells together with liposomes indicated co-aggregation. The mucoadhesive effect seems interesting as stomach cells are covered by a mucus layer. H. pylori is able to penetrate and cross the mucin rapidly to reach pH-neutral epithelium to escape the acidic environment, followed by interaction with epithelial cells. In summary, all experimental evidence is consistent with a specific interaction of pectin-coated liposomes with mucins and surface structures of H. pylori. As the coated liposomes show mucoadhesion to the negatively charged mucins, docking to stomach mucin, mucus penetration, and recognition of and adhesion to H. pylori, they can be considered a novel type of multifunctional drug carriers for local antibiotic therapy against H. pylori. KEY POINTS: • Smart, multifunctional mucoadhesive liposomes • Specific targeting against BabA/LPS of Helicobacter pylori • Inhibition of bacterial adhesion of H. pylori to human host cells • Release of antibiotic cargo.

Eradication of Helicobacter pylori: the power of nanosized formulations

Helicobacter pylori is a pathogen that is considered to cause several gastric disorders such as chronic gastritis, peptic ulcer and even gastric carcinoma. The current therapeutic regimens mainly constitute of a combination of several antimicrobial agents and proton pump inhibitors. However, the prevalence of antibiotic resistance has been significantly lowering the cure rates over the years. Nanocarriers possess unique strengths in this regard owing to the fact that they can protect the drugs (such as antibiotics) from the harsh environment in the stomach, penetrate the mucosal barrier and deliver drugs to the desired site. In this review we summarized recent studies of different antibacterial agents orally delivered by nanosized carriers for the eradication of H. pylori.

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.

Construction of catechol-grafted chitosan alginate/barium sulfate microcapsules for computed tomography real-time imaging and gastroretentive drug delivery

Background: The gastroretentive drug delivery system is an effective administration route, which can improve the bioavailability of the drug and the therapeutic effect by prolonging the release time of the drug and controlling the release rate in the stomach. Methods: Inspired by the excellent adhesion properties of mussel protein, we prepared novel catechol-grafted chitosan alginate/barium sulfate microcapsules (Cat-CA/BS MCs) with mucoadhesive properties and computed tomography (CT) imaging function for gastric drug delivery. First, barium sulfate nanoclusters used as CT contrast agent were synthesized in situ in the Cat-CA/BS MCs through a one-step electronic spinning method. Next, catechol-grafted chitosan as the mucoadhesive moiety was coated on the surface of Cat-CA/BS MCs by polyelectrolyte molecule self-assembly. Results: The prepared Cat-CA/BS MCs could effectively retained in the stomach for 48 hours and successively released ranitidine hydrochloride, which could be used for the treatment of gastric ulcer. Cat-CA/BS MCs exhibited superior CT contrast imaging properties for real-time tracking in vivo after oral administration. Conclusion: These findings demonstrate that Cat-CA/BS MCs serving as multifunctional oral drug carriers possess huge potential in gastroretentive drug delivery and non-invasive visualization.

Genipin protects against H2O2-induced oxidative damage in retinal pigment epithelial cells by promoting Nrf2 signaling

Oxidative stress serves a vital function in the pathogenesis of age-related macular degeneration (AMD); genipin (GP) possesses antioxidative properties. The present study aimed to investigate the effects of GP on retinal pigment epithelial (RPE) cells induced by H₂O₂ and the underlying mechanism. ARPE-19 cells were subjected to H₂O₂ treatment to induce oxidative damage. Cell viability was determined via an MTT assay. Reactive oxygen species (ROS) levels and cell apoptosis were detected by flow cytometry. Nuclear factor-erythroid 2-related factor-2 (Nrf2) signaling-associated and the expression of apoptosis-associated factors were measured using reverse transcription-quantitative polymerase chain reaction assay and western blotting. The results revealed that 200 µM H₂O₂ and 30 µM GP were determined to be the optimal concentrations for subsequent experimentation. GP reversed the inhibitory effects of H₂O₂ by promoting cell viability, attenuating ROS accumulation and cell apoptosis, and increased the expression of Nrf2, heme oxygenase-1 (HO-1) and NAD(P)H: Quinine oxidoreductase 1 (NQO1); Nrf2 silencing inhibited HO-1 and NQO1 expression. In addition, Nrf2 silencing enhanced the effects of H₂O₂ by promoting ROS production and cell apoptosis. Compared with H₂O₂, Nrf2 silencing further decreased the expression levels of B-cell lymphoma-2 (Bcl-2), but increased that of Bcl-2-associated X protein and cleaved-caspase-3. The results of the present study revealed that Nrf2 silencing attenuated the protective effects of GP on H₂O₂-induced injury in ARPE-19 cells by promoting apoptosis and oxidation. Collectively, GP attenuated oxidative damage induced by H₂O₂ in ARPE-19 cells. Furthermore, the molecular mechanism may be associated with the Nrf2 signaling pathway. The findings of the present study nay provide insight into a potential therapeutic agent for the treatment of AMD.

Glycans in nanomedicine, impact and perspectives

Glycans have been selected by nature for both structural and 'recognition' purposes. Taking inspiration from nature, nanomedicine exploits glycans not only as structural constituents of nanoparticles and nanostructured biomaterials but also as selective interactors of such glyco-nanotools. Surface glycosylation of nanoparticles finds application in targeting specific cells, whereas recent findings give evidence that the glycan content of cell microenvironment is able to induce the cell fate. This review will highlight the role of glycans in nanomedicine, schematizing the different uses and roles in drug-delivery systems and in biomaterials for regenerative medicine.

Nanomaterials and molecular transporters to overcome the bacterial envelope barrier: Towards advanced delivery of antibiotics

With the dramatic consequences of bacterial resistance to antibiotics, nanomaterials and molecular transporters have started to be investigated as alternative antibacterials or anti-infective carrier systems to improve the internalization of bactericidal drugs. However, the capability of nanomaterials/molecular transporters to overcome the bacterial cell envelope is poorly understood. It is critical to consider the sophisticated architecture of bacterial envelopes and reflect how nanomaterials/molecular transporters can interact with these envelopes, being the major aim of this review. The first part of this manuscript overviews the permeability of bacterial envelopes and how it limits the internalization of common antibiotic and novel oligonucleotide drugs. Subsequently we critically discuss the mechanisms that allow nanomaterials/molecular transporters to overcome the bacterial envelopes, focusing on the most promising ones to this end - siderophores, cyclodextrins, metal nanoparticles, antimicrobial/cell-penetrating peptides and fusogenic liposomes. This review may stimulate drug delivery and microbiology scientists in designing effective nanomaterials/molecular transporters against bacterial infections.

Combination drug therapy via nanocarriers against infectious diseases

Current drug therapy against infections is threatening to become obsolete due to the poor physical, chemical, biological and pharmacokinetic properties of drugs, followed by high risk of acquiring resistance. Taking into account the significant benefits of nanotechnology, nano-based delivery of anti-infectious agents is emerging as a potential approach to combat several lethal infections. Co-delivery of multiple anti-infectious agents in a single nano-based system is beginning to show significant advantages over mono-therapy, such as synergism, enhanced anti-microbial activity, broad anti-microbial spectrum, reduced resistance development, and improved and cost-effective treatment. The current review provides a detailed update on the status of various lipid and polymer based nano-systems used to co-deliver multiple anti-infectious agents against bacterial, HIV and malarial infections. It also identifies current key challenges and suggests strategies to overcome them, thus guiding formulation scientists to further optimize nano-based co-drug delivery as an approach to fight infections effectively.

Chitosan-based nanoparticles as drug delivery systems: a review on two decades of research

Chitosan (CS) is one of the most functional natural biopolymer widely used in the pharmaceutical field due to its biocompatibility and biodegradability. These privileges lead to its application in the synthesis of nanoparticles for the drug during the last two decades. This article gives rise to a general review of the different chitosan nanoparticles (CSNPs) preparation techniques: Ionic gelation, emulsion cross-linking, spray-drying, emulsion-droplet coalescence method, nanoprecipitation, reverse micellar method, desolvation method, modified ionic gelation with radial polymerisation and emulsion solvent diffusion, from the point of view of the methodological and mechanistic aspects involved. The physicochemical behaviour of CSNPs including drug loading, drug release, particles size, zeta potential and stability are briefly discussed. This review also directs to bring an outline of the major applications of CSNPs in drug delivery according to drug and route of administration. Finally, derivatives of CSNPs and CS nano-complexes are also discussed.