Synthesis and characterization of amoxicillin-loaded polymeric nanocapsules as a drug delivery system targeting Helicobacter pylori

Current developments and prospects of the antibiotic delivery systems

Antibiotics have remained the cornerstone for the treatment of bacterial infections ever since their discovery in the twentieth century. The uproar over antibiotic resistance among bacteria arising from genome plasticity and biofilm development has rendered current antibiotic therapies ineffective, urging the development of innovative therapeutic approaches. The development of antibiotic resistance among bacteria has further heightened the clinical failure of antibiotic therapy, which is often linked to its low bioavailability, side effects, and poor penetration and accumulation at the site of infection. In this review, we highlight the potential use of siderophores, antibodies, cell-penetrating peptides, antimicrobial peptides, bacteriophages, and nanoparticles to smuggle antibiotics across impermeable biological membranes to achieve therapeutically relevant concentrations of antibiotics and combat antimicrobial resistance (AMR). We will discuss the general mechanisms via which each delivery system functions and how it can be tailored to deliver antibiotics against the paradigm of mechanisms underlying antibiotic resistance.

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.

Synthesis, characterization, and cytotoxicity of doxorubicin-loaded polycaprolactone nanocapsules as controlled anti-hepatocellular carcinoma drug release system

Background

Free doxorubicin (Dox) is used as a chemotherapeutic agent against hepatocellular carcinoma (HCC), but it results in cardiotoxicty as a major side effect. Hence, a controlled Dox drug delivery system is extremely demanded.

Methods

Dox was loaded into the non-toxic biodegradable polycaprolactone (PCL) nanocapsules using the double emulsion method. Characterization of Dox-PCL nanocapsules was done using transmission electron microscopy and dynamic light scattering. Encapsulation efficiency and drug loading capacity were quantified using UV–visible spectrophotometry. Drug release was investigated in vitro at both normal (7.4) and cancer (4.8) pHs. Cytotoxicity of Dox-PCL nanocapsules against free Dox was evaluated using the MTT test on normal (Vero) and hepatic cancer (HepG2) cell lines.

Results

Spherical nanocapsules (212 ± 2 nm) were succeffully prepared with a zeta potential of (-22.3 ± 2 mv) and a polydisperse index of (0.019 ± 0.01) with a narrow size distribution pattern. The encapsulation efficiency was (73.15 ± 4%) with a drug loading capacity of (16.88 ± 2%). Importantlly, Dox-release from nanocapsules was faster at cancer pH (98%) than at physiological pH (26%). Moreover, although Dox-PCL nanocapsules were less toxic on the normal cell line (GI 50 = 17.99 ± 8.62 µg/ml) than free Dox (GI 50 = 16.53 ± 1.06 µg/ml), the encapsulated Dox showed higher toxic effect on cancer HepG2 cells compared to that caused by the free drug (GI 50 = 2.46 ± 0.49 and 4.22 ± 0.04 µg/ml, respectively).

Conclusion

The constructed Dox-PCL nanocapsules constitute a potentially controlled anti-HCC therapy with minimal systemic exposure.

Graphical Abstract

Scope and Limitations of Current Antibiotic Therapies against Helicobacter pylori: Reviewing Amoxicillin Gastroretentive Formulations

Even though general improvement of quality of life has happened around the globe, statistics show that gastric cancer is still a very serious medical concern in some regions of the world. A big portion of malignant neoplasms that develop inside the stomach are linked to an infection of Helicobacter pylori; in fact, this pathogen has already been categorized as a group 1 carcinogen by the World Health Organization (WHO). Still, the efficacy of current anti-H. pylori therapeutic approaches is insufficient and follows a worrying decreasing trend, mainly due to an exponential increase in resistance to key antibiotics. This work analyzes the clinical and biological characteristics of this pathogen, especially its link to gastric cancer, and provides a comprehensive review of current formulation trends for H. pylori eradication. Research effort has focused both on the discovery of new combinations of chemicals that function as optimized antibiotic regimens, and on the preparation of gastroretentive drug delivery systems (GRDDSs) to improve overall pharmacokinetics. Regarding the last topic, this review aims to summarize the latest trend in amoxicillin-loaded GRDDS, since this is the antibiotic that has shown the least bacterial resistance worldwide. It is expected that the current work could provide some insight into the importance of innovative options to combat this microorganism. Therefore, this review can inspire new research strategies in the development of efficient formulations for the treatment of this infection and the consequent prevention of gastric cancer.

Targeting and Killing the Ever-Challenging Ulcer Bug

TreatingHelicobacter pylori(H. pylori) infections has been a never-ending challenge, which has contributed to the high incidence of gastric cancer. The antibiotics commonly used are not reaching the infection site in its active state and in a concentration high enough to effectively kill the bacteria. In this context, amoxicillin-loaded lipid nanoparticles with carefully chosen materials were developed, namely dioleoylphosphatidylethanolamine (DOPE) as a targeting agent and Tween®80 and linolenic acid as antimicrobial agents. This work shows the ability of these nanoparticles in (i) targeting the bacteria (imaging flow cytometry) and inhibiting their adhesion to MKN-74 cells (bacteria-gastric cells adhesion model); (ii) killing the bacteria even as an antibiotic-free strategy (time-kill kineticstudies, scanning electron microscopy, and bacterial membrane permeability studies); (iii)overcoming gastrointestinal features using a newly developedin vitroinfection model that includes both physical (epithelial cells and mucus) and the chemical (acid medium) barriers; and in (iv) being incorporated in a floating system that can increase the retention time at the stomach. Overall, this work presents an effective nanosystem to deal with the ulcer-bug. Besides, it also provides two innovative tools transferable to other fields-anin vitroinfection model and a floating system to incorporate nanoparticles.