Impact of pegylation on biopharmaceutical properties of dendrimers

Quality-by-Design (QbD) Assisted Synthesis of Nanoparticle for Efficient Loading, Stabilization, and Intracellular Delivery of Bioactive for the Treatment of Arthritis

Rheumatoid arthritis (RA) is an autoimmune disorder that induces joint inflammation, cartilage injury, and bone damage. Thus far, methotrexate (MTX) is a primary DMARD drug to treat RA. Despite high efficiency, its clinical application is compromised due to delivery-associated systemic side effects. This investigation reports a Quality-by-design (QbD; Box Behnken Strategy) assisted production of a novel, innovative, and multipurpose polycation-templated approach for producing stable albumin MTX nanoparticles (pT-AMTX-NP). This approach formed a highly biocompatible MTX formulation with reduced toxicity (1.81 ± 0.54% hemolysis) compared to plain MTX (13.19 ± 2.77%; SEM:1.965). pT-AMTX-NP was found to be nanometric (Particle size: 135.86 ± 5.17 nm; PDI: 0.27) with a net surface charge of ζ -10.15 ± 2.19 mV. With 4.01-fold cationization (TNBS assay), pT-AMTX-NP showed high drug loading (64.98 ± 1.25%) and sustained MTX release under physiological conditions (up to 48 h; p < 0.001). The nanoformulation followed the Higuchi release kinetics model (R2, 0.9957). Significantly reduced burst release by 70.61% (p = 0.0002) and 12.89% (p = 0.0115) compared to plain MTX and conventional MTX-formulation (AMTX-NP), respectively. Interestingly, pT-AMTX-NP showed pH-responsive drug release bio-environment-responsive architectural change. Cell line studies in lipopolysaccharide (LPS) stimulated RAW264.7 macrophage showed a significant reduction in intracellular nitrite level following pT-AMTX-NP treatment (p < 0.01). Cellular uptake and cell viability confirmed selective cellular uptake potential in inflamed cells. Furthermore, compared to the control, the high intracellular ROS-generation was noted with pT-AMTX-NP (2.1485-fold; p < 0.01). Furthermore, hemolysis assay and stability assessments were also conducted to determine the hemocompatibility and suitable conditions for the storage of nanoformulation. The outcome of this study suggests that the developed multipurpose nanoformulation is a superior therapeutics approach for improved RA treatment. Suggestively, the developed strategy can also be adopted to benefit other clinical situations that demand to counter inflammation, cytostatic as well as psoriatic conditions.

Selective imaging, gene, and therapeutic delivery using PEGylated and pH-Sensitive nanoparticles for enhanced lung disorder treatment

Lung inflammation involves the activation of immune cells and inflammatory mediators in response to injury and infection. When inflammation persists, fibroblasts, which are resident lung cells, become activated, leading to pulmonary fibrosis (PF), abnormal wound healing, and long-term damage to the alveolar epithelium. This persistent inflammation and fibrosis can also elevate the risk of lung cancer, emphasizing the need for innovative treatments. Current therapies, such as inhaled corticosteroids (ICS) and chemotherapy, have significant limitations. Although conventional nanoparticles (NPs) provide a promising avenue for treating lung disorders, they have limited selectivity and stability. Polyethylene glycol (PEG) grafting can prevent NP aggregation and phagocytosis, thus prolonging their circulation time. When combined with targeting ligands, PEGylated NPs can deliver drugs precisely to specific cells or tissues. Moreover, pH-sensitive NPs offer the advantage of selective drug delivery to inflammatory or tumor-acidic environments, reducing side effects. These NPs can change their size, shape, or surface charge in response to pH variations, improving drug delivery efficiency. This review examines the techniques of PEGylation, the polymers used in pH-sensitive NPs, and their therapeutic applications for lung inflammation, fibrosis, and cancer. By harnessing innovative NP technologies, researchers can develop effective therapies for respiratory conditions, addressing unmet medical needs and enhancing patient outcomes.

Electrochemical behaviour of poly(amidoamine) dendrimers at micropipette-based liquid/liquid micro-interfaces

Dendrimers are macromolecules with well-defined three-dimensional structures, sizes and surface charges. In this work, four generations of poly(amidoamine) (PAMAM) dendrimers were investigated at the micro-interface between two immiscible electrolyte solutions (μITIES) to understand their electrochemical responses as simple models of ionised macromolecules. Cyclic voltammetry (CV) across a range of aqueous phase pH revealed that all four generations (G0-G3) presented diffusion-controlled ion-transfer from aqueous to organic phase, while the reverse transfers from organic to aqueous phase varied with both pH and the dendrimer generation. The larger dendrimers (G2 and G3) show an adsorption behaviour at pH ≤ 3.5, but show a diffusional response at pH ≥ 6. On the other hand, the smaller dendrimers (G0 and G1) always show a diffusional response and are not impacted by the pH. This indicates that more highly charged dendrimers condense at the interface. The reverse scan of CVs showed that an increased applied potential was required to remove (desorb) these polycations from the interfaces in comparison to smaller, less charged species. Diffusion coefficients (D) were estimated, showing a decrease with increasing generation. Limits of detection for these dendrimers by CV at the μITIES were 0.4, 0.2, 0.7 and 0.5 μM for G0 to G3, respectively, while differential pulse voltammetry lowered the LODs (0.07, 0.05, 0.09 and 0.08 μM, respectively). These study shows that the μITIES provides a simple way to detect and evaluate the electrochemical behaviour of ionised macromolecules, providing a simple illustration of detection mechanism with diffusion or adsorption processes.

Effect of polyphenolic dendrimers on biological and artificial lipid membranes

The use of dendrimers as nanovectors for nucleic acids or drugs requires the understanding of their interaction with biological membranes. This study investigates the impact of 1st generation polyphenolic carbosilane dendrimers on biological and model lipid membranes using several biophysical methods. While the increase in the z-average size of DMPC/DPPG liposomes correlated with the number of caffeic acid residues included in the dendrimer structure, dendrimers that contained polyethylene glycol chains generated lower zeta potential when interacting with a liposomal membrane. The increase in the fluorescence anisotropy of DPH and TMA-DPH probes incorporated into erythrocyte membranes predicted the ability of dendrimers to affect membrane fluidity in the hydrophobic interior and hydrophilic/polar region of a lipid bilayer. The presence of caffeic acid and polyethylene glycol chains in the dendrimer structure affected the thermodynamical properties of the membrane lipid matrix.

A new class of polyphenolic carbosilane dendrimers binds human serum albumin in a structure-dependent fashion

The use of dendrimers as drug and nucleic acid delivery systems requires knowledge of their interactions with objects on their way to the target. In the present work, we investigated the interaction of a new class of carbosilane dendrimers functionalized with polyphenolic and caffeic acid residues with human serum albumin, which is the most abundant blood protein. The addition of dendrimers to albumin solution decreased the zeta potential of albumin/dendrimer complexes as compared to free albumin, increased density of the fibrillary form of albumin, shifted fluorescence spectrum towards longer wavelengths, induced quenching of tryptophan fluorescence, and decreased ellipticity of circular dichroism resulting from a reduction in the albumin α-helix for random coil structural form. Isothermal titration calorimetry showed that, on average, one molecule of albumin was bound by 6-10 molecules of dendrimers. The zeta size confirmed the binding of the dendrimers to albumin. The interaction of dendrimers and albumin depended on the number of caffeic acid residues and polyethylene glycol modifications in the dendrimer structure. In conclusion, carbosilane polyphenolic dendrimers interact with human albumin changing its structure and electrical properties. However, the consequences of such interaction for the efficacy and side effects of these dendrimers as drug/nucleic acid delivery system requires further research.

Tumor-specific cytolysis by peptide-conjugated echogenic polymer micelles

Interest in multifunctional polymer nanoparticles for targeted delivery of anti-cancer drugs has grown significantly in recent years. In this study, tumor-targeting echogenic polymer micelles were prepared from poly(ethylene glycol) methyl ether-alkyl carbonate (mPEG-AC) derivatives, and their potential in cancer therapy was assessed. Various mPEG derivatives with carbonate linkages were synthesized via an alkyl halide reaction between mPEG and alkyl chloroformate. Micelle formation using polymer amphiphiles in aqueous media and the subsequent carbon dioxide (CO2) gas generation from the micelles was confirmed. Their ability to target neuroblastoma was substantially enhanced by incorporating the rabies virus glycoprotein (RVG) peptide. RVG-modified gas-generating micelles significantly inhibited tumor growth in a tumor-bearing mouse model owing to CO2 gas generation within tumor cells and resultant cytolytic effects, showing minimal side effects. The development of multifunctional polymer micelles may offer a promising therapeutic approach for various diseases, including cancer.

Recent Trends in Curcumin-Containing Inorganic-Based Nanoparticles Intended for In Vivo Cancer Therapy

Curcumin is a natural compound that has been widely investigated thanks to its various biological properties, including antiproliferative. This molecule acts on different cancers such as lung, breast, pancreatic, colorectal, etc. However, the bioactive actions of curcumin have limitations when its physicochemical properties compromise its pharmacological potential. As a therapeutic strategy against cancer, curcumin has been associated with inorganic nanoparticles. These nanocarriers are capable of delivering curcumin and offering physicochemical properties that synergistically enhance anticancer properties. This review highlights the different types of curcumin-based inorganic nanoparticles and discusses their physicochemical properties and in vivo anticancer activity in different models of cancer.

Recent advancements in the targeted delivery of etoposide nanomedicine for cancer therapy: A comprehensive review

Etoposide (ETO), a popular anticancer drug that inhibits topoisomerase II enzymes, may be administered more effectively and efficiently due to nanomedicine. The therapeutic application of ETO is constrained by its limited solubility, weak absorption, and severe side effects. This article summarizes substantial progress made in the development of ETO nanomedicine for the treatment of cancer. It discusses various organic and inorganic nanostructures used to load or affix ETOs, such as lipids, liposomes, polymeric nanoparticles (NPs), dendrimers, micelles, gold NPs, iron oxide NPs, and silica NPs. In addition, it evaluates the structural properties of these nanostructures, such as their size, zeta potential, encapsulation efficiency, and drug release mechanism, as well as their in vitro or in vivo performance. The article also emphasizes the co-delivery of ETO with other medications or agents to produce synergistic effects or combat drug resistance in the treatment of cancer. It concludes with a discussion of the challenges and potential avenues for clinical translation of ETO nanomedicine.

Dendrimer: An update on recent developments and future opportunities for the brain tumors diagnosis and treatment

A brain tumor is an uncontrolled cell proliferation, a mass of tissue composed of cells that grow and divide abnormally and appear to be uncontrollable by the processes that normally control normal cells. Approximately 25,690 primary malignant brain tumors are discovered each year, 70% of which originate in glial cells. It has been observed that the blood-brain barrier (BBB) limits the distribution of drugs into the tumour environment, which complicates the oncological therapy of malignant brain tumours. Numerous studies have found that nanocarriers have demonstrated significant therapeutic efficacy in brain diseases. This review, based on a non-systematic search of the existing literature, provides an update on the existing knowledge of the types of dendrimers, synthesis methods, and mechanisms of action in relation to brain tumours. It also discusses the use of dendrimers in the diagnosis and treatment of brain tumours and the future possibilities of dendrimers. Dendrimers are of particular interest in the diagnosis and treatment of brain tumours because they can transport biochemical agents across the BBB to the tumour and into the brain after systemic administration. Dendrimers are being used to develop novel therapeutics such as prolonged release of drugs, immunotherapy, and antineoplastic effects. The use of PAMAM, PPI, PLL and surface engineered dendrimers has proven revolutionary in the effective diagnosis and treatment of brain tumours.

Neuro-nanotechnology: diagnostic and therapeutic nano-based strategies in applied neuroscience

Artificial, de-novo manufactured materials (with controlled nano-sized characteristics) have been progressively used by neuroscientists during the last several decades. The introduction of novel implantable bioelectronics interfaces that are better suited to their biological targets is one example of an innovation that has emerged as a result of advanced nanostructures and implantable bioelectronics interfaces, which has increased the potential of prostheses and neural interfaces. The unique physical-chemical properties of nanoparticles have also facilitated the development of novel imaging instruments for advanced laboratory systems, as well as intelligently manufactured scaffolds and microelectrodes and other technologies designed to increase our understanding of neural tissue processes. The incorporation of nanotechnology into physiology and cell biology enables the tailoring of molecular interactions. This involves unique interactions with neurons and glial cells in neuroscience. Technology solutions intended to effectively interact with neuronal cells, improved molecular-based diagnostic techniques, biomaterials and hybridized compounds utilized for neural regeneration, neuroprotection, and targeted delivery of medicines as well as small chemicals across the blood-brain barrier are all purposes of the present article.

Recent advances in multifunctional dendrimer-based nanoprobes for breast cancer theranostics

Breast cancer (BC) undoubtedly is one of the most common type of cancers amongst women, which causes about 5 million deaths annually. The treatments and diagnostic therapy choices currently available for Breast Cancer is very much limited . Advancements in novel nanocarrier could be a promising strategy for diagnosis and treatments of this deadly disease. Dendrimer nanoformulation could be functionalized and explored for efficient targeting of overexpressed receptors on Breast Cancer cells to achieve targeted drug delivery, for diagnostics and to overcome the resistance of the cells towards particular chemotherapeutic. Additionally, the dendrimer have shown promising potential in the improvement of therapeutic value for Breast Cancer therapy by achieving synergistic co-delivery of chemotherapeutics and genetic materials for multidirectional treatment. In this review, we have highlighted the application of dendrimer as novel multifunctional nanoplatforms for the treatment and diagnosis of Breast Cancer.

Chlorotoxin and Lung Cancer: A Targeting Perspective for Drug Delivery

In the generational evolution of nano-based drug delivery carriers, active targeting has been a major milestone for improved and selective drug accumulation in tissues and cell types beyond the existing passive targeting capabilities. Among the various active targeting moieties, chlorotoxin, a peptide extracted from scorpions, demonstrated promising tumor cell accumulation and selection. With lung cancer being among the leading diagnoses of cancer-related deaths in both men and women, novel therapeutic methodologies utilizing nanotechnology for drug delivery emerged. Given chlorotoxin's promising biological activity, we explore its potential against lung cancer and its utilization for active targeting against this cancer's tumor cells. Our analysis indicates that despite the extensive chlorotoxin's research against glioblastoma, lung cancer research with the molecule has been limited, despite some promising early results.

Exploring the Structural Diversity of DNA Bottlebrush Polymers Using an Oligonucleotide Macromonomer Approach

Herein, we demonstrate that macromonomers consisting of organics-soluble, chemically protected oligonucleotides (protDNA) and poly(ethylene glycol) (PEG) chains can be converted into bottlebrush polymers of distinct architectures via ring-opening metathesis polymerization (ROMP). Using a custom norbornene-containing phosphoramidite, two types of macromonomers were obtained: a linear norbornene-protDNA-PEG structure and a Y-shaped structure where the polymerizable norbornene group is situated at the junction where protDNA and PEG meet. With this strategy, the PEG chains can be placed either near the backbone of the bottlebrush or on its periphery, and in principle anywhere between these two extremes by adjusting the norbornene location, which makes this strategy attractive for constructing architecturally sophisticated oligonucleotide-containing copolymers.

Prevention of Herpesviridae Infections by Cationic PEGylated Carbosilane Dendrimers

Infections caused by viruses from the Herpesviridae family produce some of the most prevalent transmitted diseases in the world, constituting a serious global public health issue. Some of the virus properties such as latency and the appearance of resistance to antiviral treatments complicate the development of effective therapies capable of facing the infection. In this context, dendrimers present themselves as promising alternatives to current treatments. In this study, we propose the use of PEGylated cationic carbosilane dendrimers as inhibitors of herpes simplex virus 2 (HSV-2) and human cytomegalovirus (HCMV)infections. Studies of mitochondrial toxicity, membrane integrity, internalization and viral infection inhibition indicated that G2-SN15-PEG, G3-SN31-PEG, G2-SN15-PEG fluorescein isothiocyanate (FITC) labeled and G3-SN31-PEG-FITC dendrimers are valid candidates to target HSV-2 and HCMV infections since they are biocompatible, can be effectively internalized and are able to significantly inhibit both infections. Later studies (including viral inactivation, binding inhibition, heparan sulphate proteoglycans (HSPG)binding and surface plasmon resonance assays) confirmed that inhibition takes place at first infection stages. More precisely, these studies established that their attachment to cell membrane heparan sulphate proteoglycans impede the interaction between viral glycoproteins and these cell receptors, thus preventing infection. Altogether, our research confirmed the high capacity of these PEGylated carbosilane dendrimers to prevent HSV-2 and HCMV infections, making them valid candidates as antiviral agents against Herpesviridae infections.

The Antibacterial Effect of PEGylated Carbosilane Dendrimers on P. aeruginosa Alone and in Combination with Phage-Derived Endolysin

The search for new microbicide compounds is of an urgent need, especially against difficult-to-eradicate biofilm-forming bacteria. One attractive option is the application of cationic multivalent dendrimers as antibacterials and also as carriers of active molecules. These compounds require an adequate hydrophilic/hydrophobic structural balance to maximize the effect. Herein, we evaluated the antimicrobial activity of cationic carbosilane (CBS) dendrimers unmodified or modified with polyethylene glycol (PEG) units, against planktonic and biofilm-forming P. aeruginosa culture. Our study revealed that the presence of PEG destabilized the hydrophilic/hydrophobic balance but reduced the antibacterial activity measured by microbiological cultivation methods, laser interferometry and fluorescence microscopy. On the other hand, the activity can be improved by the combination of the CBS dendrimers with endolysin, a bacteriophage-encoded peptidoglycan hydrolase. This enzyme applied in the absence of the cationic CBS dendrimers is ineffective against Gram-negative bacteria because of the protective outer membrane shield. However, the endolysin-CBS dendrimer mixture enables the penetration through the membrane and then deterioration of the peptidoglycan layer, providing a synergic antimicrobial effect.

Toxicity And Surface Modification Of Dendrimers: A Critical Review

As compared to other nano polymers, dendrimers have novel three dimensional, synthetic hyperbranched, nano-polymeric structures. The characteristic of these supramolecular dendritic structures has a high degree of significant surface as well as core functionality in the transportation of drugs for targeted therapy, specifically in host-guest response, gene transfer therapy and imaging of biological systems. However, there are conflicting shreds of evidence regarding biological safety and dendrimers toxicity due to their positive charge at the surface. It includes cytotoxicity, hemolytic toxicity, haematological toxicity, immunogenicity and in vivo toxicity. Therefore to resolve these problems surface modification of the dendrimer group is one of the methods. From that point, this review involves different strategies which reduce the toxicity and improve the biocompatibility of different types of dendrimers. From that viewpoint, we broaden the structural and safe characteristics of the dendrimers in the biomedical and pharmaceutical fields.

Developments in Treatment Methodologies Using Dendrimers for Infectious Diseases

Dendrimers comprise a specific group of macromolecules, which combine structural properties of both single molecules and long expanded polymers. The three-dimensional form of dendrimers and the extensive possibilities for use of additional substrates for their construction creates a multivalent potential and a wide possibility for medical, diagnostic and environmental purposes. Depending on their composition and structure, dendrimers have been of interest in many fields of science, ranging from chemistry, biotechnology to biochemical applications. These compounds have found wide application from the production of catalysts for their use as antibacterial, antifungal and antiviral agents. Of particular interest are peptide dendrimers as a medium for transport of therapeutic substances: synthetic vaccines against parasites, bacteria and viruses, contrast agents used in MRI, antibodies and genetic material. This review focuses on the description of the current classes of dendrimers, the methodology for their synthesis and briefly drawbacks of their properties and their use as potential therapies against infectious diseases.

Ferrocifen Loaded Lipid Nanocapsules: A Promising Anticancer Medication against Multidrug Resistant Tumors

Resistance of cancer cells to current chemotherapeutic drugs has obliged the scientific community to seek innovative compounds. Ferrocifens, lipophilic organometallic compounds composed of a tamoxifen scaffold covalently bound to a ferrocene moiety, have shown very interesting antiproliferative, cytotoxic and immunologic effects. The formation of ferrocenyl quinone methide plays a crucial role in the multifaceted activity of ferrocifens. Lipid nanocapsules (LNCs), meanwhile, are nanoparticles obtained by a free organic solvent process. LNCs consist of an oily core surrounded by amphiphilic surfactants and are perfectly adapted to encapsulate these hydrophobic compounds. The different in vitro and in vivo experiments performed with this ferrocifen-loaded nanocarrier have revealed promising results in several multidrug-resistant cancer cell lines such as glioblastoma, breast cancer and metastatic melanoma, alone or in combination with other therapies. This review provides an exhaustive summary of the use of ferrocifen-loaded LNCs as a promising nanomedicine, outlining the ferrocifen mechanisms of action on cancer cells, the nanocarrier formulation process and the in vivo results obtained over the last two decades.

Human Serum Albumin as Multifunctional Nanocarrier for Cancer Therapy

Human serum albumin or simply called albumin is a flexible protein employed as a carrier in the fabrication of albumin-based nanocarriers (ANCs) for the administration of cancer therapeutics. Albumin can contribute enhanced tumour specificity, reduced drug induced cytotoxicity and retain concentration of the therapeutically active agent such as drug, peptide, protein, and gene for a prolonged time duration. Nevertheless, apart from cancer management, ANCs are also employed in the diagnosis, imaging, and multimodal cancer therapy. This article figures out salient characteristics, design as well as categories of ANCs in the context of their application in cancer management. In addition, this review article discusses the fabrication methods of ANCs, use of ANCs in gene, cancer, and multimodal therapy along with cancer diagnosis and imaging. Lastly, this review also briefly discusses about (ANCs) formulations, commercial products, and those under clinical testing.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

Stereoregular cyclic p-tolyl-siloxanes with alkyl, O- and N-containing groups as promising reagents for the synthesis of functionalized organosiloxanes

Preparation methodology for a series of hydrophobic and amphiphilic well-defined stereoregular cyclic p-tolyl-substituted siloxanes has been proposed.

PEGylation of Polyethylenimine Lowers Acute Toxicity while Retaining Anti-Biofilm and β-Lactam Potentiation Properties against Antibiotic-Resistant Pathogens

Bacterial biofilms, often impenetrable to antibiotic medications, are a leading cause of poor wound healing. The prognosis is worse for wounds with biofilms of antimicrobial-resistant (AMR) bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant S. epidermidis (MRSE), and multi-drug resistant Pseudomonas aeruginosa (MDR-PA). Resistance hinders initial treatment of standard-of-care antibiotics. The persistence of MRSA, MRSE, and/or MDR-PA often allows acute infections to become chronic wound infections. The water-soluble hydrophilic properties of low-molecular-weight (600 Da) branched polyethylenimine (600 Da BPEI) enable easy drug delivery to directly attack AMR and biofilms in the wound environment as a topical agent for wound treatment. To mitigate toxicity issues, we have modified 600 Da BPEI with polyethylene glycol (PEG) in a straightforward one-step reaction. The PEG-BPEI molecules disable β-lactam resistance in MRSA, MRSE, and MDR-PA while also having the ability to dissolve established biofilms. PEG-BPEI accomplishes these tasks independently, resulting in a multifunction potentiation agent. We envision wound treatment with antibiotics given topically, orally, or intravenously in which external application of PEG-BPEIs disables biofilms and resistance mechanisms. In the absence of a robust pipeline of new drugs, existing drugs and regimens must be re-evaluated as combination(s) with potentiators. The PEGylation of 600 Da BPEI provides new opportunities to meet this goal with a single compound whose multifunction properties are retained while lowering acute toxicity.

Telodendrimers: Promising Architectural Polymers for Drug Delivery

Architectural complexity has played a key role in enhancing the efficacy of nanocarriers for a variety of applications, including those in the biomedical field. With the continued evolution in designing macromolecules-based nanoparticles for drug delivery, the combination approach of using important features of linear polymers with dendrimers has offered an advantageous and viable platform. Such nanostructures, which are commonly referred to as telodendrimers, are hybrids of linear polymers covalently linked with different dendrimer generations and backbones. There is considerable variety in selection from widely studied linear polymers and dendrimers, which can help tune the overall composition of the resulting hybrid structures. This review highlights the advances in articulating syntheses of these macromolecules, and the contributions these are making in facilitating therapeutic administration. Limited progress has been made in the design and synthesis of these hybrid macromolecules, and it is through an understanding of their physicochemical properties and aqueous self-assembly that one can expect to fully exploit their potential in drug delivery.

Nanocarriers in effective pulmonary delivery of siRNA: current approaches and challenges

Research on siRNA is increasing due to its wide applicability as a therapeutic agent in irreversible medical conditions. siRNA inhibits expression of the specific gene after its delivery from formulation to cytosol region of a cell. RNAi (RNA interference) is a mechanism by which siRNA is silencing gene expression for a particular disease. Numerous studies revealed that naked siRNA delivery is not preferred due to instability and poor pharmacokinetic performance. Nanocarriers based delivery of siRNA has the advantage to overcome physiological barriers and protect the integrity of siRNA from degradation by RNAase. Various diseases like lung cancer, cystic fibrosis, asthma, etc can be treated effectively by local lung delivery. The selective targeted therapeutic action in diseased organ and least off targeted cytotoxicity are the key benefits of pulmonary delivery. The current review highlights recent developments in pulmonary delivery of siRNA with novel nanosized formulation approach with the proven in vitro/in vivo applications.

Highlighting the impact of chitosan on the development of gastroretentive drug delivery systems

The development of gastroretentive systems have been growing lately due to the high demand for carriers that increase drug bioavailability and therapeutic effectiveness after oral administration. Most of systems reported up to now are based on chitosan (CS) due to its peculiar properties, such as cationic nature, biodegradability, biocompatibility and important mucoadhesiveness, which make CS a promising biopolymer to design effective gastroretentive systems. In light of this, we reported in this review the CS versatility to fabricate different types of nano- and microstructured gastroretentive systems. For a better understanding of the gastric retention mechanisms, we highlighted expandable, density-based, magnetic, mucoadhesive and superporous systems. The biological and chemical properties of CS, anatomophysiological aspects related to gastrointestinal tract (GIT) and some applications of these systems are also described here. Overall, this review may assist researchers to explore new strategies to design safe and efficient gastroretentive systems in order to popularize them in the treatment of diseases and clinical practices.

Dendrimers as efficient nanocarriers for the protection and delivery of bioactive phytochemicals

The genesis of dendrimers can be considered as a revolution in nano-scaled bioactive delivery systems. These structures possess a unique potential in encapsulating/entrapping bioactive ingredients due to their tree-like nature. Therefore, they could swiftly obtain a valuable statue in nutraceutical, pharmaceutical and medical sciences. Phytochemicals, as a large proportion of bioactives, have been studied and used by scholars in several fields of pharmacology, medical, food, and cosmetic for many years. But, the solubility, stability, and bioavailability issues have always been recognized as limiting factors in their application. Therefore, the main aim of this study is representing the use of dendrimers as novel nanocarriers for phytochemical bioactive compounds to deal with these problems. Hence, after a brief review of phytochemical ingredients, the text is commenced with a detailed explanation of dendrimers, including definitions, types, generations, synthesizing methods, and safety issues; then is continued with demonstration of their applications in encapsulation of phytochemical bioactive compounds and their active/passive delivery by dendrimers. Dendrimers provide a vast and appropriate surface to entrap the targeted phytochemical bioactive ingredients. Several parameters can affect the yield of nanoencapsulation by dendrimers, including their generation, type of end groups, surface charge, core structure, pH, and ambient factors. Another important issue of dendrimers is related to their toxicity. Cationic dendrimers, particularly PAMAM can be toxic to body cells through attaching to the cell membranes and disturbing their functions. However, a number of solutions have been suggested to decrease their toxicity.

Effect of PEGylation on the biological properties of cationic carbosilane dendronized gold nanoparticles

Heterofunctionalized gold nanoparticles (AuNPs) were obtained in a one pot reaction of gold precursor with cationic carbosilane dendrons (first to third generations, 1-3G) and (polyethylene)glycol (PEG) ligands in the presence of a reducing agent. The final dendron/PEG proportion on AuNPs depends on the initial dendron/PEG ratio (3/1, 1/1, 1/3) and dendron generation. AuNPs were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), ultraviolet spectroscopy (UV-VIS), thermogravimetric analysis (TGA), nuclear magnetic resonance (¹H NMR) and zeta potential (ZP). Several assays have been carried out to determine the relevance of PEG/dendron ratio and dendron generation in the biomedical properties of PEGylated AuNPs and the results have been compared with those obtained for non-PEGylated AuNPs. Finally, analyses of PEG recognition by anti-PEG antibodies were carried out. In general, haemolysis, platelet aggregation and toxicity were reduced after PEGylation of AuNPs, the effect being dependent on dendron generation and dendron/PEG ratio. Dendron generation determines the exposure of PEG ligand and the interaction of this ligand with AuNPs environment. On the other hand, increasing PEG proportion diminishes toxicity but also favors interaction with antibodies.

The potential of dendrimer in delivery of therapeutics for dentistry

Dendrimers are hyperbranched nanoparticle structures along with its surface modifications can to be used in dental biomaterials for biomimetic remineralisation of enamel and dentin. The review highlights the therapeutic applications of dendrimers in the field of dentistry. It addresses the possible mechanisms of enhancement of mechanical properties of adhesives and resins structure. Dendrimers due to its unique construction of possessing inner hydrophobic and outer hydrophilic structure can act as drug carrier for delivery of antimicrobial drugs for treatment of periodontal diseases and at peripheral dental implant areas. Dendrimers due to its hyperbranched structures can provides a unique drug delivery vehicle for delivery of a drug at specific site for sustained release for therapeutic effects. Thus, dendrimers can be one of the most important constituents which can be incorporated in dental biomaterials for better outcomes in dentistry.

Evaluating liver uptake and distribution of different poly(2-methyl-2-oxazoline) modified lysine dendrimers following intravenous administration

Residual charge and drug modification determine the cellular distribution in the liver for poly(2-methyl-2-oxazoline) modified lysine dendrimers.

'Dendrimer-Cationized-Albumin' encrusted polymeric nanoparticle improves BBB penetration and anticancer activity of doxorubicin

Glioblastoma is one of the most rapaciously growing cancer within the brain with an average lifespan of 12-15 months (5-year survival <3-4%). Doxorubicin (DOX) is clinically utilized as a first line drug in the treatment of Glioblastoma, however, its restricted entry into the brain via the blood-brain barrier (BBB), limited blood-tumor barrier (BTB) permeability, hemotoxicity, short mean half-life of 1-3 hr as well as rapid body clearance results in tremendously diminished bioactivity in glioblastoma. Dendrimer-Cationized-Albumin (dCatAlb) was synthesized following the carboxyl activation technique and the synthesized biopolymer was characterized by FTIR, MALDI-TOF and zeta potential. The prepared dCatAlb was encrusted on DOX-loaded PLGA nanoparticle core to develop a novel hybrid DOX nanoformulation (dCatAlb-pDNP; particle size: 156 ± 10.85 nm; ƺ: -10.0 ± 2.1 mV surface charge). The formulated dCatAlb-pDNP showed a unique pH-dependent DOX release profile, diminished hemolytic toxicity, higher drug uptake (<0.001) and cytotoxicity in U87MG glioblastoma cells, increase levels of caspase-3 gene in U87MG cells (approximately 5.35-fold higher) inferred that anticancer activity is primarily taking place through caspase-mediated apoptosis mechanism. The developed novel DOX nanoformulation also showed superior trans-epithelial permeation transport across monolayer bEnd.3 cells as well as notable biocompatibility and stability. The dCatAlb-pDNP showed enhanced BBB permeation efficacy as confirmed permeation assay in bEnd.3 cell-based model. The long-term formulation stability of developed nanoformulations was studied by storing them at 5 ± 2 °C and 30 ± 2 °C/60 ± 5% Relative Humidity (% RH) in the stability chamber for a period of 60 days (ICHQ1A (R2)). The outcomes of this investigation evidently indicate that dCatAlb-pDNP offers superior anticancer activity of DOX in glioblastoma cells while significantly improving its BBB permeation. The developed formulation is a biocompatible, safer and commercially viable approach to delivering DOX selectively in sustained manner glioblastoma while countering its hemolytic toxic effect, which is a major ongoing issue with conventional DOX injectable available in the market today.

Modified PAMAM vehicles for effective TRAIL gene delivery to colon adenocarcinoma: in vitro and in vivo evaluation

TRAIL (tumour necrosis factor-related apoptosis-inducing ligand) gene therapy is considered as one of the promising approaches for cancer treatment. Polyamidoamine (PAMAM) is one of the most extensively applied polymeric vector in gene delivery. In the current study, PAMAM (G4 and G5) dendrimers were modified with alkyl-carboxylate chain, PEG and cholesteryl chloroformate in order to enhance transfection efficiency through overcoming extracellular and intracellular barriers while reducing PAMAM cytotoxicity. Gene delivery efficiency of synthetized vectors was evaluated by both GFP (green fluorescent protein) reporter gene and TRAIL plasmid in colon cancer cells, in vitro and in vivo. The obtained results demonstrated that PAMAM G4-alkyl-PEG (3%)-Chol (5%)-TRAIL complexes at C/P ratio 4 could significantly increase cell death (29.45%) in comparison with unmodified PAMAM vector (15.5%). Moreover, in vivo study in C26 tumor-bearing BALB/c mice suggested that the prepared non-toxic safe vector could inhibit the tumor growth. This study represented the potent vehicle based on cholesterol-grafted PAMAM dendrimers with alkyl-PEG modification for efficient gene delivery in vitro and in vivo.

PEGylation of polypropylenimine dendrimers: effects on cytotoxicity, DNA condensation, gene delivery and expression in cancer cells

Diaminobutyric polypropylenimine (DAB) dendrimers have been shown to be highly efficient non-viral gene delivery systems for cancer therapy. However, their cytotoxicity currently limits their applications. To overcome this issue, PEGylation of DAB dendrimer, using various PEG molecular weights and dendrimer generations, has been attempted to decrease the cytotoxicity and enhance the DNA condensation, size and zeta potential, cellular uptake and transfection efficacy of these dendriplexes. Among all the PEGylated dendrimers synthesized, generation 3- and generation 4-DAB conjugated to low molecular weight PEG (2 kDa) at a dendrimer: DNA ratio of 20:1 and 10:1 resulted in an increase in gene expression on almost all tested cancer cells lines (by up to 3.2-fold compared to unmodified dendrimer in A431 cells). The highest level of β-galactosidase gene expression (10.07 × 10^-3 ± 0.09 × 10^-3 U/mL) was obtained following treatment of B16F10-Luc cells with G4-dendrimer PEGylated with PEG2K at a dendrimer: DNA ratio of 20:1. These delivery systems significantly decreased cytotoxicity on B16F10-Luc cells, by more than 3.4-fold compared to unmodified dendrimer. PEGylated generations 3- and 4-DAB dendrimers are therefore promising gene delivery systems for cancer therapy, combining low cytotoxicity and high transfection efficacy.

A triple modality BSA-coated dendritic nanoplatform for NIR imaging, enhanced tumor penetration and anticancer therapy

Functional theranostic systems for drug delivery capable of concurrent near-infrared (NIR) fluorescence imaging, active tumor targeting and anticancer therapies are desired for concise cancer diagnosis and treatment. Dendrimers with controllable size and surface functionalities are good candidates for such platforms. However, integration of active targeting ligands and imaging agents separately on the surface or encapsulation of the imaging agents in the inner core of the dendrimers will result in a more complex composition or reduced drug loading efficiency. Herein, we reported a PAMAM-based theranostic system, with a simple integrin-specific imaging ligand prepared from two motifs. One motif is a NIR carbocyanine fluorescent dye (Cyp) for precise in vivo monitoring of the system and identification of tumor or cancer cells, and the other is a novel tumor-penetrating cyclic peptide (CRGDKGPDC, abbreviated iRGD). BSA was non-covalently bonded with Cyp to reduce NIR agent fluorescence-quenching aggregates and enhance imaging signals. The chemotherapy effect of these dendritic systems was achieved by encapsulating paclitaxel into the hydrophobic interior of the dendrimers. In vitro and in vivo targeting and penetrating studies revealed that a significantly high amount of the dendritic systems was endocytosed by HepG2 cells and enhanced accumulation and penetration at tumor sites. Our safety evaluation showed that masking of cationic-end groups of PAMAM to neutral or anionic groups has resulted in decreased or even zero-toxicity. The preliminary antitumor efficacy of the dendritic system was evaluated. In vitro and in vivo studies confirmed that paclitaxel-encapsulated functionalized PAMAM can efficiently kill HepG2 cancer cells. In conclusion, our functionalized theranostic dendritic system could be a promising nanocarrier to effectively deliver drugs to deep tumor regions for anticancer therapy.

Biodegradable PEG-dendritic block copolymers: synthesis and biofunctionality assessment as vectors of siRNA

One important drawback of most of the currently used dendrimers for biomedical applications is their high stability under physiological conditions that can result in cytotoxicity or complications induced by the accumulation of non-degradable synthetic materials in the organism. Particularly in the gene therapy field, vector stability can further hinder the intracellular release of the nucleic acid from the dendriplex, consequently leading to low transfection efficiencies. Therefore, biodegradable cationic dendritic structures have been eagerly awaited. However, the development of these dendritic nanocarriers is challenging because of the undesired and/or premature degradation observed during their synthesis and/or application. Here, we report new hybrid-biodegradable, biocompatible, non-toxic, and water-soluble azide-terminated PEG-GATGE dendritic block copolymers, based on a gallic acid (GA) core and triethylene glycol (TG) butanoate arms, incorporating ester bonds (E) at the dendritic arms/shell. Their successful functionalization by "click" chemistry with unprotected alkynated amines allowed complexation and delivery of siRNA. The hydrophobic character of the GATGE building unit confers to these hydrolyzable dendritic bionanomaterials a great ability to complex, protect and mediate the cellular internalization of siRNA. Moreover, the localization of the degradation points at the dendritic periphery, close to the complexed siRNA, was found to be important for nucleic acid release from the nanoparticles, rendering a significant improvement of the transfection efficiency compared to their hydrolytically stable PEG-GATG copolymer counterparts. The present study puts forward these biodegradable PEG-dendritic block copolymers not only as suitable vectors for nucleic acids, but also as new avenues for further developments exploring their use in theranostics.

Cellular internalization and transport of biodegradable polyester dendrimers on a model of the pulmonary epithelium and their formulation in pressurized metered-dose inhalers

The purpose of this study was to evaluate the effect of generation and surface PEGylation of degradable polyester-based dendrimers nanocarriers on their interactions with an in vitro model of the pulmonary epithelium as well as to assess the ability to formulate such carriers in propellant-based, portable oral-inhalation devices to determine their potential for local and systemic delivery of drugs to and through the lungs. Hydroxyl (-OH) terminated polyester dendrimers of generation 3 and 4 (G3, and G4) were synthesized using a divergent approach. G4 was surface-modified with PEG (1,000Da). All dendrimers and their building blocks were determined to be highly compatible with the model pulmonary epithelium, with toxicity profiles much more favorable than non-degradable polyamidoamine dendrimers (PAMAM). The transport of the species from the apical to basolateral side across polarized Calu-3 monolayers showed to be generation and surface-chemistry (PEGylation) dependent. The extent of the transport is modulated by their interaction with the polarized epithelium and their transient opening of the tight junctions. G3 was the one most efficiently internalized by the epithelium, and had a small impact on the integrity of the monolayer. On the other hand, the PEGylated G4 was the one least internalized by the polarized epithelium, and at the same time had a more pronounced transient impact on the cellular junctions, resulting in more efficient transport across the cell monolayer. PEGylation of the dendrimer surface played other roles as well. PEGylation modulated the degradation profile of the dendrimer, slowing the process in a step-wise fashion - first the PEG layer is shed and then the dendrimer starts degrading. PEGylation also helped increase the solvation of the nanocarriers by the hydrofluoroalkane propellant used in pressurized metered-dose inhalers, resulting in formulations with excellent dispersibility and aerosol quality (deep lung deposition of 88.5%), despite their very small geometric diameter. The combined in vitro and formulation performance results shown here demonstrated that degradable, modified polyester dendrimers may serve as a valuable platform that can be tailored to target the lung tissue for treating local diseases, or the circulation, using the lungs as pathway to the bloodstream.