Polypeptides and polyaminoacids in drug delivery

Degradable Polymeric Bio(nano)materials and Their Biomedical Applications: A Comprehensive Overview and Recent Updates

Degradable polymers (both biomacromolecules and several synthetic polymers) for biomedical applications have been promising very much in the recent past due to their low cost, biocompatibility, flexibility, and minimal side effects. Here, we present an overview with updated information on natural and synthetic degradable polymers where a brief account on different polysaccharides, proteins, and synthetic polymers viz. polyesters/polyamino acids/polyanhydrides/polyphosphazenes/polyurethanes relevant to biomedical applications has been provided. The various approaches for the transformation of these polymers by physical/chemical means viz. cross-linking, as polyblends, nanocomposites/hybrid composites, interpenetrating complexes, interpolymer/polyion complexes, functionalization, polymer conjugates, and block and graft copolymers, are described. The degradation mechanism, drug loading profiles, and toxicological aspects of polymeric nanoparticles formed are also defined. Biomedical applications of these degradable polymer-based biomaterials in and as wound dressing/healing, biosensors, drug delivery systems, tissue engineering, and regenerative medicine, etc., are highlighted. In addition, the use of such nano systems to solve current drug delivery problems is briefly reviewed.

Peptide-Based siRNA Nanocomplexes Targeting Hepatic Stellate Cells

Liver fibrosis is the excessive accumulation of extracellular matrix (ECM) in the liver due to chronic injuries and inflammation. These injuries activate and transform quiescent hepatic stellate cells (HSCs) into proliferative myofibroblast-like cells, which are the key contributors to the secretin of ECM in the fibrotic liver. The insulin-like growth factor 2 receptor (IGF2R) is a multifunctional receptor that is overexpressed on activated HSCs and is a specific molecular marker of activated HSCs in the fibrotic liver. We recently discovered an IGF2R-specific peptide that significantly increases the binding affinity and uptake of a protein-based siRNA nanocomplex to activated HSCs. However, there is a potential concern about the immunogenicity of protein-based siRNA delivery systems. In this study, we used the IGF2R-specific peptide to modify a small peptide-based siRNA nanocomplex for HSC-specific drug delivery. We incorporated a short spacer and glutamate residues into the IGF2R peptides. The siRNA nanocomplex modified with the IGF2R-3GK6E peptide demonstrated higher HSC specificity compared to an unmodified nanocomplex. This peptide-based nanocomplex provides a promising platform to effectively deliver Pcbp2 siRNA to activated HSCs for the treatment of liver fibrosis.

A Molecular Theory of Polypeptide Adsorption at Inorganic Surfaces

A faithful description of polypeptide adsorption at ionizable surfaces remains a theoretical challenge from a molecular perspective due to the strong coupling of local thermodynamic nonideality and ionizations of both the adsorbate and substrate that are sensitive to the solution condition such as pH, ion valence, and salt concentration. Building upon a recently developed coarse-grained model for natural amino acids in bulk electrolyte solutions, here we report a molecular theory applicable to polypeptide adsorption on ionizable inorganic surfaces over a broad range of inhomogeneous conditions. Our thermodynamic model is able to account for diverse solution effects as well as the amino-acid sequence on polypeptide adsorption and surface association such as hydrogen bonding or bidentate coordination. The theoretical predictions have been validated by extensive comparison with experimental data for the adsorption isotherms of three representative polypeptides at a titanium surface.

Recent advances in biopolymer-based hemostatic materials

Hemorrhage is the leading cause of trauma-related deaths, in hospital and pre-hospital settings. Hemostasis is a complex mechanism that involves a cascade of clotting factors and proteins that result in the formation of a strong clot. In certain surgical and emergency situations, hemostatic agents are needed to achieve faster blood coagulation to prevent the patient from experiencing a severe hemorrhagic shock. Therefore, it is critical to consider appropriate materials and designs for hemostatic agents. Many materials have been fabricated as hemostatic agents, including synthetic and naturally derived polymers. However, compared to synthetic polymers, natural polymers or biopolymers, which include polysaccharides and polypeptides, have greater biocompatibility, biodegradability, and processibility. Thus, in this review, we focus on biopolymer-based hemostatic agents of different forms, such as powder, particles, sponges, and hydrogels. Finally, we discuss biopolymer-based hemostats currently in clinical trials and offer insight into next-generation hemostats for clinical translation.

Engineered polymer nanoparticles incorporating l-amino acid groups as affinity reagents for fibrinogen

Synthetic polymer hydrogel nanoparticles (NPs) were developed to function as abiotic affinity reagents for fibrinogen. These NPs were made using both temperature-sensitive N-isopropyl acrylamide (NIPAm) and l-amino acid monomers. Five kinds of l-amino acids were acryloylated to obtain functional monomers: l-phenylalanine (Phe) and l-leucine (Leu) with hydrophobic side chains, l-glutamic acid (Glu) with negative charges, and l-lysine (Lys) and l-arginine (Arg) with positive charges. After incubating the NPs with fibrinogen, γ-globulin, and human serum albumin (HSA) respectively, the NPs that incorporated N-acryloyl-Arg monomers (AArg@NPs) showed the strongest and most specific binding affinity to fibrinogen, when compared with γ-globulin and HSA. Additionally, the fibrinogen-AArg binding model had the best docking scores, and this may be due to the interaction of positively charged AArg@NPs and the negatively charged fibrinogen D domain and the hydrophobic interaction between them. The specific adsorption of AArg@NPs to fibrinogen was also confirmed by the immunoprecipitation assay, as the AArg@NPs selectively trapped the fibrinogen from a human plasma protein mixture. AArg@NPs had a strong selectivity for, and specificity to, fibrinogen and may be developed as a potential human fibrinogen-specific affinity reagent.

A Guideline for the Synthesis of Amino-Acid-Functionalized Monomers and Their Polymerizations

Amino acids have emerged as a sustainable source for the design of functional polymers. Besides their wide availability, especially their high degree of biocompatibility makes them appealing for a broad range of applications in the biomedical research field. In addition to these favorable characteristics, the versatility of reactive functional groups in amino acids (i.e., carboxylic acids, amines, thiols, and hydroxyl groups) makes them suitable starting materials for various polymerization approaches, which include step- and chain-growth reactions. This review aims to provide an overview of strategies to incorporate amino acids into polymers. To this end, it focuses on the preparation of polymerizable monomers from amino acids, which yield main chain or side chain-functionalized polymers. Furthermore, postpolymerization modification approaches for polymer side chain functionalization are discussed. Amino acids are presented as a versatile platform for the development of polymers with tailored properties.

Polyamide/Poly(Amino Acid) Polymers for Drug Delivery

Polymers have always played a critical role in the development of novel drug delivery systems by providing the sustained, controlled and targeted release of both hydrophobic and hydrophilic drugs. Among the different polymers, polyamides or poly(amino acid)s exhibit distinct features such as good biocompatibility, slow degradability and flexible physicochemical modification. The degradation rates of poly(amino acid)s are influenced by the hydrophilicity of the amino acids that make up the polymer. Poly(amino acid)s are extensively used in the formulation of chemotherapeutics to achieve selective delivery for an appropriate duration of time in order to lessen the drug-related side effects and increase the anti-tumor efficacy. This review highlights various poly(amino acid) polymers used in drug delivery along with new developments in their utility. A thorough discussion on anticancer agents incorporated into poly(amino acid) micellar systems that are under clinical evaluation is included.

Comparison of Efficacy and Peripheral Neuropathy of Solvent-based Paclitaxel with Paclitaxel Poliglumex and NK105: A Systematic Review and Metaanalysis

Background and Introduction: Peripheral neuropathy is one of the most common dose-limiting side effects of solvent-based paclitaxel. Paclitaxel poliglumex (PPX) and NK105 were developed to overcome the paclitaxel induced peripheral neuropathy. However, the incidence of peripheral neuropathy induced by PPX and NK105 was reported higher than solvent-based paclitaxel, but evidence remains inconsistent.

METHODS

The article was reported in accordance with PRISMA Guidelines (Registration number: CRD42021245313). We conducted a meta-analysis to compare the incidence and severity of peripheral neuropathy between solvent-based paclitaxel, PPX and NK105 mono-chemotherapy.

RESULTS

Results revealed that no significant difference exists between the incidence of all grade peripheral neuropathy among the solvent-based paclitaxel, PPX and NK105 treated groups. While, the incidence of high grade peripheral neuropathy induced by NK105 was lower than two other groups. Moreover, the overall survival was not improved in PPX compared with other groups. However, NK105 demonstrated significant longer overall survival in patients with cancer.

CONCLUSION

Current evidence suggests more attention should be paid to the paclitaxel poliglumex re-formulation.

Recent Advances in Polymer Nanomaterials for Drug Delivery of Adjuvants in Colorectal Cancer Treatment: A Scientific-Technological Analysis and Review

Colorectal cancer (CRC) is the type with the second highest morbidity. Recently, a great number of bioactive compounds and encapsulation techniques have been developed. Thus, this paper aims to review the drug delivery strategies for chemotherapy adjuvant treatments for CRC, including an initial scientific-technological analysis of the papers and patents related to cancer, CRC, and adjuvant treatments. For 2018, a total of 167,366 cancer-related papers and 306,240 patents were found. Adjuvant treatments represented 39.3% of the total CRC patents, indicating the importance of adjuvants in the prognosis of patients. Chemotherapy adjuvants can be divided into two groups, natural and synthetic (5-fluorouracil and derivatives). Both groups can be encapsulated using polymers. Polymer-based drug delivery systems can be classified according to polymer nature. From those, anionic polymers have garnered the most attention, because they are pH responsive. The use of polymers tailors the desorption profile, improving drug bioavailability and enhancing the local treatment of CRC via oral administration. Finally, it can be concluded that antioxidants are emerging compounds that can complement today's chemotherapy treatments. In the long term, encapsulated antioxidants will replace synthetic drugs and will play an important role in curing CRC.

Versatile protamine nanocapsules to restore miR-145 levels and interfere tumor growth in colorectal cancer cells

MicroRNAs (miRNAs) play a key role on gene expression regulation contributing to cell homeostasis, and they are highly dysregulated in cancer. Consequently, miRNA-based therapies are an attractive approach to develop novel anticancer strategies. The main objective of this work was to explore the full potential of protamine nanocapsules (Pr NCs) to develop an anticancer therapy based on the restoration of oncosuppressor miR-145, downregulated in colorectal cancer cells. The composition of Pr NCs was defined based on the selection of surfactants, and protamine that would enable an efficient association and intracellular delivery of miRNA mimics according to the layer-by-layer approach, and the encapsulation of curcumin within the oily core. After exposure of colorectal cancer cells with (i) miR-145 and (ii) curcumin-loaded Pr NCs, a strong increase in the intracellular levels of miR-145, which translated into a decreased cell proliferation rate and migration capacity of the treated cells, was observed. The potential of exploiting Pr NCs for the co-delivery of both biomolecules, miRNAs and curcumin, has also been proved. All together, here we evaluate the possibility to use Pr NCs to efficiently increase the intracellular levels of the oncosuppressor miR-145.

Hyaluronic Acid Nanocapsules as a Platform for Needle-Free Vaccination

Vaccination faces many challenges nowadays, and among them the use of adjuvant molecules and needle-free administration are some of the most demanding. The combination of transcutaneous vaccination and nanomedicine through a rationally designed new-formulation could be the solution to this problem. This study focuses on this rational design. For this purpose, new hyaluronic acid nanocapsules (HA-NCs) have been developed. This new formulation has an oily nucleus with immunoadjuvant properties (due to α tocopherol) and a shell made of hyaluronic acid (HA) and decorated with ovalbumin (OVA) as the model antigen. The resulting nanocapsules are smaller than 100 nm, have a negative superficial charge and have a population that is homogeneously distributed. The systems show high colloidal stability in storage and physiological conditions and high OVA association without losing their integrity. The elevated interaction of the novel formulation with the immune system was demonstrated through complement activation and macrophage viability studies. Ex vivo studies using a pig skin model show the ability of these novel nanocapsules to penetrate and retain OVA in higher quantities in skin when compared to this antigen in the control solution. Due to these findings, HA-NCs are an interesting platform for needle-free vaccination.

Self-Propelled and Targeted Drug Delivery of Poly(aspartic acid)/Iron-Zinc Microrocket in the Stomach

For many medical treatments, particularly cancer, it is necessary to develop a biocompatible microscale device that can carry a sufficient amount of a drug and deliver it to target sites. While chemically powered micromotors have been applied in live animal therapy, many of them are difficult to biodegrade in vivo, which might cause toxicity and side effects. Here, we report on a microdevice that consists of a poly(aspartic acid) (PASP) microtube, a thin Fe intermediate layer, and a core of Zn. This device can be propelled using gastric acid as a fuel. After adsorption of doxorubicin onto a PASP surface, the microrocket can carry drugs, magnetically locate targets, permeate the gastric mucus gel layer, and increase drug retention in the stomach without inducing an obvious toxic reaction. All materials in the microrockets are biocompatible and biodegradable and can be readily decomposed by the gastric acid or by proteases in the digestive tract. Such microrockets, made with poly(amino acid)s, will extend the practical biomedical applications of micro- and nanomotors.

Effects of nanoparticle chromium mixed with γ-polyglutamic acid on the chromium bioavailability, growth performance, serum parameters and carcass traits of pigs

Because chromium is a mineral that is difficult to absorb, nanotechnology was used to produce nanoparticle trivalent chromium, which has a reduced particle size and increased surface area to increase chromium bioavailability. The aim of the present study was to investigate the effect of dietary supplementation nanoparticle trivalent chromium with or without γ-polyglutamic acid (γ-PGA) on the chromium bioavailability, growth performance, serum parameters and carcass traits of pigs. In Trial 1, eight growing pigs (Landrace × Yorkshire × Duroc; LYD) with an initial average weight of 51.3 ± 2.0 kg were used in a 4 × 4 Latin square design as the control group (without chromium supplements), the chromium picolinate group (CrPic), the nanoparticle chromium picolinate group (NanoCrPic) and the nanoparticle chromium picolinate mixed with γ-polyglutamic acid (NanoCrPic–PGA) group. Chromium was added at a level of 200 μg/kg to a basal diet containing 728 µg Cr/kg DM, using different forms of chromium, so as to evaluate the chromium bioavailability. The results of Trial 1 indicated that the bioavailability of the supplemented chromium was as follows: NanoCrPic–PGA > NanoCrPic > CrPic (P < 0.05). In Trial 2, 64 LYD growing pigs (average bodyweight 74.46 ± 3.9 kg) were randomly allotted to the same four dietary treatment groups as in Trial 1 and the same levels of chromium were added to the diet. Each group contained four pens and there were four pigs in each pen. The experimental results indicated that the gain:feed ratio in the NanoCrPic–PGA group was better than that in the NanoCrPic group (P < 0.001). The serum chromium concentrations in the NanoCrPic–PGA group were higher than in the control group (P < 0.05), the serum insulin concentration in the chromium supplementation groups was lower than that in the control group (P < 0.05), and blood glucose in the NanoCrPic group was lower than that in the control group (P < 0.05). The carcass traits were not affected by chromium supplementation. In conclusion, nanoparticle trivalent chromium, either alone or together with γ-PGA, improved chromium bioavailability and feeding effectiveness.

Protamine Nanocapsules for the Development of Thermostable Adjuvanted Nanovaccines

One of the main challenges in the development of vaccine has been to improve their stability at room temperature and eliminate the limitations associated with the cold chain storage. In this paper, we describe the development and optimization of thermostable nanocarriers consisting of an oily core with immunostimulating activity, containing squalene or α tocopherol surrounded by a protamine shell. The results showed that these nanocapsules can efficiently associate the recombinant hepatitis B surface antigen (rHBsAg) without compromising its antigenicity. Furthermore, the freeze-dried protamine nanocapsules were able to preserve the integrity and bioactivity of the associated antigen upon storage for at least 12 months at room temperature. In vitro studies evidenced the high internalization of the nanocapsules by immunocompetent cells, followed by cytokine secretion and complement activation. In vivo studies showed the capacity of rHBsAg-loaded nanocapsules to elicit protective levels upon intramuscular or intranasal administration to mice. Overall, our data indicate that protamine nanocapsules are an innovative thermostable nanovaccine platform for improved antigen delivery.

Lower-Sized Chitosan Nanocapsules for Transcutaneous Antigen Delivery

Transcutaneous vaccination has several advantages including having a noninvasive route and needle-free administration; nonetheless developing an effective transdermal formulation has not been an easy task because skin physiology, particularly the stratum corneum, does not allow antigen penetration. Size is a crucial parameter for successful active molecule administration through the skin. Here we report a new core-shell structure rationally developed for transcutaneous antigen delivery. The resulting multifunctional carrier has an oily core with immune adjuvant properties and a polymeric corona made of chitosan. This system has a size of around 100 nm and a positive zeta potential. The new formulation is stable in storage and physiological conditions. Ovalbumin (OVA) was used as the antigen model and the developed nanocapsules show high association efficiency (75%). Chitosan nanocapsules have high interaction with the immune system which was demonstrated by complement activation and also did not affect cell viability in the macrophage cell line. Finally, ex vivo studies using a pig skin model show that OVA associated to the chitosan nanocapsules developed in this study penetrated and were retained better than OVA in solution. Thus, the physicochemical properties and their adequate characteristics make this carrier an excellent platform for transcutaneous antigen delivery.

Assessment of the permeability and toxicity of polymeric nanocapsules using the zebrafish model

Aim: To assess the capacity of a new drug delivery nanocapsule (NC) with a double shell of hyaluronic acid and protamine to overcome biological barriers using the zebrafish model. Materials & methods: NCs were prepared by the solvent displacement method, tagged with fluorescent makers and physicochemically characterized. Toxicity was evaluated according to the Fish Embryo Acute Toxicity test, and permeability was tested by exposing zebrafish, with and without chorion, to the fluorescent NCs. Results: Toxicity of NCs was very low as compared with that of a control nanoemulsion. Double-shell NCs were able to cross chorion and skin. Conclusion: Beyond the potential value of hyaluronic acid:protamine NCs for overcoming epithelial barriers, this works highlights the utility of zebrafish for fast screening of nanocarriers.

Rational design of protamine nanocapsules as antigen delivery carriers

Current challenges in global immunization indicate the demand for new delivery strategies, which could be applied to the development of new vaccines against emerging diseases, as well as to improve safety and efficacy of currently existing vaccine formulations. Here, we report a novel antigen nanocarrier consisting of an oily core and a protamine shell, further stabilized with pegylated surfactants. These nanocarriers, named protamine nanocapsules, were rationally designed to promote the intracellular delivery of antigens to immunocompetent cells and to trigger an efficient and long-lasting immune response. Protamine nanocapsules have nanometric size, positive zeta potential and high association capacity for H1N1 influenza hemagglutinin, a protein that was used here as a model antigen. The new formulation shows an attractive stability profile both, as an aqueous suspension or a freeze-dried powder formulation. In vitro studies showed that protamine nanocapsules were efficiently internalized by macrophages without eliciting significant toxicity. In vivo studies indicate that antigen-loaded nanocapsules trigger immune responses comparable to those achieved with alum, even when using significantly lower antigen doses, thus indicating their adjuvant properties. These promising in vivo data, alongside with their versatility for the loading of different antigens and oily immunomodulators and their excellent stability profile, make these nanocapsules a promising platform for the delivery of antigens.

CHEMICAL COMPOUNDS

Protamine sulphate (PubChem SID: 7849283), Sodium Cholate (PubChem CID: 23668194), Miglyol (PubChem CID: 53471835), α tocopherol (PubChem CID: 14985), Tween® 20(PubChem CID: 443314), Tween® 80(PubChem CID: 5281955), TPGS (PubChem CID: 71406).

Biodegradable polymeric nanostructures in therapeutic applications: opportunities and challenges

Biodegradable polymeric nanostructures (BPNs) have shown great promise in different therapeutic applications such as diagnosis, imaging, drug delivery, cosmetics, organ implants, and tissue engineering.

Mesomeric configuration makes polyleucine micelle an optimal nanocarrier

Mesomeric polyleucine micelle with cRGD decoration is selected as a promising targeting drug delivery system.

A computational study of the self-assembly of the RFFFR peptide

The β-amyloid peptide sequence, LVFFA, inspired the investigation of the fiber formation potential of the RFFFR peptide. The self-assembly was studied in silico by coarse grained-, atomistic molecular dynamics simulations and semi-empirical quantum mechanical calculations. The fiber formation was found to occur according to a three step process starting with the emergence of small aggregates that join together and form fiber segments that eventually form one continuous fiber. From a series of simulations the critical fiber concentration was determined to be in the interval between 70 mM and 100 mM. To obtain more structural information of the stable fiber, the final coarse grained configuration was backtransformed to atomistic detail. Based on this structure a 10 ns atomistic simulation was performed, which suggests that the fiber is stabilized by hydrogen bonds and water mediated hydrogen bonds. These stabilizing bonds are, however, reduced by competitive protein-water hydrogen bonds. Hence, π-stacking is suspected to play a larger role in fiber stabilization. The π-stacking of intermolecular Phe residues are found to favor a T-shaped stacking mode, while intramolecular π-stacking interactions assume a broad variety of modes from the parallel displaced mode to the T-shaped stacking mode and modes in between, with equal probability. Selected snapshots from the atomistic simulation were geometry optimized using semi-empirical quantum mechanical methods to validate the fiber stability and π-stacking configuration. An average Cα-RMSD was determined to be 2.68 Å. These findings indicate that the fiber may be used as a novel model system for the study of amyloid fibers or self-assembled conductive biowires, respectively.

Protamine-based nanoparticles as new antigen delivery systems

The use of biodegradable nanoparticles as antigen delivery vehicles is an attractive approach to overcome the problems associated with the use of Alum-based classical adjuvants. Herein we report, the design and development of protamine-based nanoparticles as novel antigen delivery systems, using recombinant hepatitis B surface antigen as a model viral antigen. The nanoparticles, composed of protamine and a polysaccharide (hyaluronic acid or alginate), were obtained using a mild ionic cross-linking technique. The size and surface charge of the nanoparticles could be modulated by adjusting the ratio of the components. Prototypes with optimal physicochemical characteristics and satisfactory colloidal stability were selected for the assessment of their antigen loading capacity, antigen stability during storage and in vitro and in vivo proof-of-concept studies. In vitro studies showed that antigen-loaded nanoparticles induced the secretion of cytokines by macrophages more efficiently than the antigen in solution, thus indicating a potential adjuvant effect of the nanoparticles. Finally, in vivo studies showed the capacity of these systems to trigger efficient immune responses against the hepatitis B antigen following intramuscular administration, suggesting the potential interest of protamine-polysaccharide nanoparticles as antigen delivery systems.

Competitive binding-accelerated insulin release from a polypeptide nanogel for potential therapy of diabetes

A novel core cross-linked glycopolypeptide nanogel was prepared for glucose-triggered insulin delivery.

Self-assembled micelles of amphiphilic poly(L-phenylalanine)-b-poly(L-serine) polypeptides for tumor-targeted delivery

The aim of this work was to design, synthesize, and characterize self-assembled micelles based on polypeptides as a potential antitumor drug carrier. Amphiphilic poly(l-phenylalanine)-b-poly(l-serine) (PFS) polypeptides were obtained through the polymerization of N-carboxyanhydride. As a novel hydrophilic segment, poly(l-serine) was utilized to enhance tumor targeting due to a large demand of tumors for serine. PFS could self-assemble into micelles with an average diameter of 110–240 nm and a slightly negative charge. PFS polypeptides adopted random coil in pH 7.4 phosphate-buffered saline and could partly transform to α-helix induced by trifluoroethanol. PFS micelles with a low critical micelle concentration of 4.0 μg mL⁻¹ were stable in pH 5–9 buffers and serum albumin solution. PFS micelles had a loading capacity of 3.8% for coumarin-6 and exhibited a sustained drug release. Coumarin-6 loaded rhodamine B isothiocyanate-labeled PFS micelles were incubated with Huh-7 tumor cells to study the correlation between drugs and carriers during endocytosis. The uptake of drugs was consistent with the micelles, illustrating that the intracellular transport of drugs highly depended on the micelles. PFS micelles diffused in whole cytoplasm while coumarin-6 assumed localized distribution, suggesting that the micelles could release the loaded drugs in particular areas. The internalization mechanism of PFS micelles was involved with clathrin-mediated endocytosis and macropinocytosis. Excess serine inhibited the uptake of PFS micelles, which demonstrated that serine receptors played a positive role in the internalization of PFS. The more interesting thing was that the uptake inhibition impacted on normal cells but not on tumor cells at the physiological concentration of serine. The difference in the uptake of PFS micelles was fourfold as high between the tumor cells and the normal cells, which indicated that PFS micelles had good tumor targeting in vitro. In conclusion, PFS micelles reported in this work were a promising drug delivery system for tumor targeting therapy.

Anionic nanoparticles based on Span 80 as low-cost, simple and efficient non-viral gene-transfection systems

The existing strategies in the design of non-viral vectors for gene therapy are primarily conceived for cationic systems. However, the safety concerns associated with the use of positively charged systems for nucleic acid delivery and several reports regarding the efficacy of negatively charged systems highlights the need for improved gene-delivery vectors. With these premises in mind, we investigated the development of new negatively charged nanoparticles based on Sorbitan esters (Span(®)) – extremely cheap excipients broadly used in the pharmaceutical industry – on the basis of a simple, one-step and easily scalable procedure. For their specific use in gene therapy, we have incorporated oleylamine (OA) or poly-L-arginine (PA) into these nanosystems. Thus, we used Sorbitan monooleate (Span(®) 80) to design Span(®) 80-oleylamine and Span(®) 80-poly-L-arginine nanosystems (SP-OA and SP-PA, respectively). These systems can associate with the model plasmid pEGFP-C3 and show mean particle sizes of 304 nm and 247 nm and surface charges of -13 mV and -17 mV, respectively. The nanoparticles developed were evaluated in terms of in vitro cell viability and transfection ability. Both systems exhibited an appropriate cell-toxicity profile and are able to transfect the plasmid effectively. Specifically, the nanosystems including OA among their components provided higher transfection levels than the SP-PA nanoparticles. In conclusion, anionic nanoparticles based on Span(®) 80 can be considered low-cost, simple and efficient non-viral anionic gene-transfection systems.

A new potential nano-oncological therapy based on polyamino acid nanocapsules

A critical objective in cancer therapy is to reduce the systemic toxicity through the modification of the biodistribution of anticancer drugs. Herein, we disclose a new biodegradable nanocarrier, polyglutamic acid (PGA) nanocapsules, and present the in vivo pharmacokinetics/toxicity proof-of-concept for the anticancer drug plitidepsin. These novel nanocapsules were prepared using a modified solvent displacement technique where the polyamino acid was electrostatically deposited onto the lipid core. The nanocapsules exhibited an average size of 200 nm, a negative zeta potential and a great capacity for the encapsulation of plitidepsin (encapsulation efficiency above 90%). In addition, the nanocapsules could be freeze-dried and showed an adequate stability profile upon storage. Finally, the in vivo proof-of-concept studies performed in mice indicated that the encapsulation provided the drug with a prolonged blood circulation and a significantly reduced toxicity. In fact, the maximum tolerated dose of the nanoencapsulated drug was more than 3 times that of the reference formulation (Cremophor® EL plitidepsin solution). Overall, beyond the value of this specific formulation, the work reported here represents the evidence of the potential of polyamino acid nanocapsules in nano-oncological therapy.

Polymeric micelles for multidrug delivery and combination therapy

The use of conventional therapy based on a single therapeutic agent is not optimal to treat human diseases. The concept called "combination therapy", based on simultaneous administration of multiple therapeutics is recognized as a more efficient solution. Interestingly, this concept has been in use since ancient times in traditional herbal remedies with drug combinations, despite mechanisms of these therapeutics not fully comprehended by scientists. This idea has been recently re-enacted in modern scenarios with the introduction of polymeric micelles loaded with several drugs as multidrug nanocarriers. This Concept article presents current research and developments on the application of polymeric micelles for multidrug delivery and combination therapy. The principles of micelle formation, their structure, and the developments and concept of multidrug delivery are introduced, followed by discussion on recent advances of multidrug delivery concepts directed towards targeted drug delivery and cancer, gene, and RNA therapies. The advantages of various polymeric micelles designed for different applications, and new developments combined with diagnostics and imaging are elucidated. A compilation work from our group based on multidrug-loaded micelles as carriers in drug-releasing implants for local delivery systems based on titania nanotubes is summarized. Finally, an overview of recent developments and prospective outlook for future trends in this field is given.

Redox-sensitive shell-crosslinked polypeptide-block-polysaccharide micelles for efficient intracellular anticancer drug delivery

Redox-responsive SCMs based on amphiphilic PBLG-b-dextran with good biocompatibility are synthesized and used for efficient intracellular drug delivery. The molecular structures and SCMs characteristics are characterized by (1) H NMR, FT-IR, TEM, and DLS. The hydrodynamic radius of SCMs increases gradually in PBS due to the cleavage of disulfide bond in micellar shell caused by the presence of GSH. The encapsulation efficiency and release kinetics of DOX are investigated. The fastest DOX release is observed under intracellular-mimicking reductive environments. An MTT assay demonstrates that DOX-loaded SCMs show higher cellular proliferation inhibition against GSH-OEt pretreated HeLa and HepG2 than that of the non-pretreated and BSO-pretreated ones.

Nanovaccines : nanocarriers for antigen delivery

Vaccination has become one of the most important health interventions of our times, revolutionizing health care, and improving the quality of life and life expectancy of millions all over the world. In spite of this, vaccine research remains a vast field for innovation and improvement. Indeed, the shift towards the use of sub-unit antigens, much safer but less immunogenic, and the recognized need to facilitate the access to vaccines in the global framework is currently stimulating the search for safe and efficient adjuvants and delivery technologies. Within this context, nanocarriers have gained particular attention over the last years and appear as one of the most promising strategies for antigen delivery. A number of biomaterials and technologies can be used to design nanovaccines that fulfill the requirements of new vaccination approaches, such as single-dose and transmucosal immunization, critical for achieving a widespread coverage while reducing the overall costs in relation to traditional forms of vaccination. Here we present an overview of the current state of nanocarriers for antigen delivery, developed with the perspective of contributing to the global vaccination goal.