Self-assembled nanoparticles based on modified cationic dipeptides and DNA: novel systems for gene delivery

Self-assembled and Zn(II)-coordinated dipeptide nanoparticles with membrane-rupturing action on bacteria

Metal ion-coordinated self-assembled short-chain amino acid peptide molecules with multi-photon excitation wavelengths and their photoluminescence properties are advantageous for fluorescence-based diagnostics and treatments of biological diseases based on their extra features of antibacterial agents. We have designed a novel strategy based on tryptophan molecule coordinated with Zn(II) ions in the form of biocompatible spherical nanoparticles of diameter 30-80 nm which have been used for antibacterial treatments against different kinds of pathogenic bacteria (Escherichia coli, Salmonella typhimurium, and Pseudomonas). Preferably, we have used tryptophan-phenylalanine (Trp-Phe), a dipeptide molecule having tryptophan as principal material against E. coli strains as antimicrobial agents for surface rupturing and killing purposes. Furthermore, based on single amino acid, tryptophan, self-assembled and Zn(II)-coordinated dipeptide nanoparticles (Zn-DPNPs) were studied against three types of multi-drug-resistant bacteria as an active antimicrobial agent. These antibacterial efficient nanoparticles may have best alternative of antibiotic drugs for clinical applications. The capability of self-assembled fluorescence behavior of Zn-coordinated dipeptide molecules and higher hydrophobicity against bacterial cell wall will perform as antimicrobial fluorescent agents. KEY POINTS: • Zn(II) and Cu(II) better coordinated into self-assembled NPs. • Fluorescence signals showed interaction of NPs with gram -ve cell wall. • Significant surface-damaging effects were observed in the case of Cu-DPNPs and Zn-DPNPs.

Dipeptide nanostructures: Synthesis, interactions, advantages and biomedical applications

Short peptides are important in the design of self-assembled materials due to their versatility and flexibility. Self-assembled dipeptides, a group of peptide nanostructures, have highly attractive uses in the field of biomedicine. Recently these materials have proved to be important nanostructures because of their biocompatibility, low-cost and simplicity of synthesis, functionality/easy tunability and nano dimensions. Although there are different studies on peptide and protein-based nanostructures, more information about self-assembled nanostructures for dipeptides is still required to discover the advantages, challenges, importance, synthesis, interactions, and applications. This review describes and discusses the self-assembled dipeptide nanostructures especially for biomedical applications.

Conformationally restricted, dipeptide-based, self-assembled nanoparticles for efficient vancomycin delivery

Aim: Emergence of vancomycin (Van) resistance, and usage of its higher dose and short half-life are posing a serious concern. Slow and sustained release of Van using a nanodelivery system may overcome these problems. Materials & methods: Arginine-α,β-dehydrophenylalanine (RΔF) was synthesized using solution-phase synthesis which self-assembled into nanospheres. Van was entrapped in the nanoparticles (NPs). In vitro and in vivo efficacy of Van-RΔF was determined using broth microdilution and the mouse thigh infection model, respectively. Results & conclusion: Van-RΔF NPs efficiently inhibited bacterial growth (Staphylococcus aureus), while Van alone showed limited growth inhibition in in vitro. Intravenous administration of Van-RΔF in mice with bacterial thigh infection showed enhanced efficacy (double) compared with Van alone, which indicates its high potential for further development.

Conformationally Restricted Dipeptide-Based Nanoparticles for Delivery of siRNA in Experimental Liver Cirrhosis

Liver cirrhosis is a major health problem with multiple associated complications. The presently available drug delivery systems showed moderate site-specific delivery of antifibrotic molecules to the diseased liver; therefore, research on more effective and selective delivery systems in the context of liver cirrhosis remains a necessity in clinical investigation. The aim of the present study was to develop a peptide-based targeted nanocarrier to deliver an oligonucleotide to the hepatic sinusoidal and perivascular regions of the cirrhotic liver. We have synthesized and characterized a conformationally restricted targeted pentapeptide (RΔFRGD), which contains an unnatural amino acid, α,β-dehydrophenylalanine (ΔF). The RΔFRGD self-assembled into spherical nanoparticles (NPs) and was characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Next, we investigated the delivery potential of the pentapeptide-based NPs to make a stable complex with a well-established small interference RNA and studied its site-specific delivery in experimental liver cirrhosis. We used siNR4A1 of the orphan nuclear receptor 4A1 (NR4A1), a well-known regulatory checkpoint for controlling liver fibrosis. Peptide NPs and their complex with siNR4A1 showed high biocompatibility against various mammalian cell lines. Hepatic tissue biodistribution analysis illustrated that targeted NPs predominantly accumulated in the cirrhotic liver compared to normal rats, specifically in sinusoidal and perivascular areas. A significant downregulation of the NR4A1 mRNA expression (-70%) andlower levels of the NR4A1/GAPDH ratio (-55%) were observed in the RΔFRGD-siNR4A1 nanocomplex-treated group in comparison to the RΔFRGD-vehicle group (RΔFRGD-Veh) at the gene and protein levels, respectively. In addition, in vivo inhibition of NR4A1 produced a significant aggravation in hepatic fibrosis compared with siRNA-vehicle-treated rats (+41% in the MT stain). The novel pentapeptide-based targeted delivery system can be further evaluated and validated for therapeutic purposes in various pathological conditions.

Amino Acids, Peptides, and Proteins: Implications for Nanotechnological Applications in Biosensing and Drug/Gene Delivery

Over various scientific fields in biochemistry, amino acids have been highlighted in research works. Protein, peptide- and amino acid-based drug delivery systems have proficiently transformed nanotechnology via immense flexibility in their features for attaching various drug molecules and biodegradable polymers. In this regard, novel nanostructures including carbon nanotubes, electrospun carbon nanofibers, gold nanoislands, and metal-based nanoparticles have been introduced as nanosensors for accurate detection of these organic compounds. These nanostructures can bind the biological receptor to the sensor surface and increase the surface area of the working electrode, significantly enhancing the biosensor performance. Interestingly, protein-based nanocarriers have also emerged as useful drug and gene delivery platforms. This is important since, despite recent advancements, there are still biological barriers and other obstacles limiting gene and drug delivery efficacy. Currently available strategies for gene therapy are not cost-effective, and they do not deliver the genetic cargo effectively to target sites. With rapid advancements in nanotechnology, novel gene delivery systems are introduced as nonviral vectors such as protein, peptide, and amino acid-based nanostructures. These nano-based delivery platforms can be tailored into functional transformation using proteins and peptides ligands based nanocarriers, usually overexpressed in the specified diseases. The purpose of this review is to shed light on traditional and nanotechnology-based methods to detect amino acids, peptides, and proteins. Furthermore, new insights into the potential of amino protein-based nanoassemblies for targeted drug delivery or gene transfer are presented.

From Folding to Assembly: Functional Supramolecular Architectures of Peptides Comprised of Non-Canonical Amino Acids

The engineering of biological molecules is the fundamental concept behind the design of complex materials with desirable functions. Over the last few decades, peptides and proteins have emerged as useful building blocks for well-defined nanostructures with controlled size and dimensions. Short peptides in particular have received much attention due to their inherent biocompatibility, lower synthetic cost, and ease of tunability. In addition to the diverse self-assembling properties of short peptides comprising coded amino acids and their emerging applications in nanotechnology, there is now growing interest in the properties of peptides composed of non-canonical amino acids. Such non-natural oligomers have been shown in recent years to form well-defined secondary structures similar to natural proteins, with the ability to self-assemble to generate a wide variety of nanostructures with excellent biostability. This review describes recent events in the development of supramolecular assemblies of peptides composed completely of non-coded amino acids and their hybrid analogues. Special attention is paid to understanding the supramolecular assemblies at the atomic level and to considering their potential applications in nanotechnology.

SAPdb: A database of short peptides and the corresponding nanostructures formed by self-assembly

Nanostructures generated by self-assembly of peptides yield nanomaterials that have many therapeutic applications, including drug delivery and biomedical engineering, due to their low cytotoxicity and higher uptake by targeted cells owing to their high affinity and specificity towards cell surface receptors. Despite the promising implications of this rapidly expanding field, there is no dedicated resource to study peptide nanostructures. This study endeavours to create a repository of short peptides, which may prove to be the best models to study ordered nanostructures formed by peptide self-assembly. SAPdb has a repertoire of 1049 entries of experimentally validated nanostructures formed by the self-assembly of small peptides. It consists of 328 tripeptides, 701 dipeptides, and 20 single amino acids with some conjugate partners. Each entry encompasses comprehensive information about the peptide, such as chemical modifications, the type of nanostructure formed, experimental conditions like pH, temperature, solvent required for the self-assembly, etc. Our analysis indicates that peptides containing aromatic amino acids favour the formation of self-assembling nanostructures. Additionally, we observed that these peptides form different nanostructures under different experimental conditions. SAPdb provides this comprehensive information in a hassle-free tabulated manner at a glance. User-friendly browsing, searching, and analysis modules have been integrated for easy data retrieval, data comparison, and examination of properties. We anticipate SAPdb to be a valuable repository for researchers engaged in the burgeoning arena of nanobiotechnology. It is freely available at https://webs.iiitd.edu.in/raghava/sapdb.

Dehydropeptide Supramolecular Hydrogels and Nanostructures as Potential Peptidomimetic Biomedical Materials

Supramolecular peptide hydrogels are gaining increased attention, owing to their potential in a variety of biomedical applications. Their physical properties are similar to those of the extracellular matrix (ECM), which is key to their applications in the cell culture of specialized cells, tissue engineering, skin regeneration, and wound healing. The structure of these hydrogels usually consists of a di- or tripeptide capped on the N-terminus with a hydrophobic aromatic group, such as Fmoc or naphthalene. Although these peptide conjugates can offer advantages over other types of gelators such as cross-linked polymers, they usually possess the limitation of being particularly sensitive to proteolysis by endogenous proteases. One of the strategies reported that can overcome this barrier is to use a peptidomimetic strategy, in which natural amino acids are switched for non-proteinogenic analogues, such as D-amino acids, β-amino acids, or dehydroamino acids. Such peptides usually possess much greater resistance to enzymatic hydrolysis. Peptides containing dehydroamino acids, i.e., dehydropeptides, are particularly interesting, as the presence of the double bond also introduces a conformational restraint to the peptide backbone, resulting in (often predictable) changes to the secondary structure of the peptide. This review focuses on peptide hydrogels and related nanostructures, where α,β-didehydro-α-amino acids have been successfully incorporated into the structure of peptide hydrogelators, and the resulting properties are discussed in terms of their potential biomedical applications. Where appropriate, their properties are compared with those of the corresponding peptide hydrogelator composed of canonical amino acids. In a wider context, we consider the presence of dehydroamino acids in natural compounds and medicinally important compounds as well as their limitations, and we consider some of the synthetic strategies for obtaining dehydropeptides. Finally, we consider the future direction for this research area.

Recent advances in the fabrication and bio-medical applications of self-assembled dipeptide nanostructures

Molecular self-assembly is a widespread natural phenomenon and has inspired several researchers to synthesize a compendium of nano/microstructures with widespread applications. Biomolecules like proteins, peptides and lipids are used as building blocks to fabricate various nanomaterials. Supramolecular peptide self-assembly continue to play a significant role in forming diverse nanostructures with numerous biomedical applications; however, dipeptides offer distinctive supremacy in their ability to self-assemble and produce a variety of nanostructures. Though several reviews have articulated the progress in the field of longer peptides or polymers and their self-assembling behavior, there is a paucity of reviews or literature covering the emerging field of dipeptide-based nanostructures. In this review, our goal is to present the recent advancements in dipeptide-based nanostructures with their potential applications.

Recent Progress in Ionic Coassembly of Cationic Peptides and Anionic Species

Peptide assembly has been extensively exploited as a promising platform for the creation of hierarchical nanostructures and tailor-made bioactive materials. Ionic coassembly of cationic peptides and anionic species is paving the way to provide particularly important contribution to this topic. In this review, the recent progress of ionic coassembly soft materials derived from the electrostatic coupling between cationic peptides and anionic species in aqueous solution is systematically summarized. The presentation of this review starts from a brief background on the general importance and advantages of peptide-based ionic coassembly. After that, diverse combinations of cationic peptides with small anions, macro- and/or oligo-anions, anionic polymers, and inorganic polyoxometalates are described. Emphasis is placed on the hierarchical structures, value-added properties, and applications. The molecular design of cationic peptides and the general principles behind the ionic coassembled structures are discussed. It is summarized that the combination of interesting and unique characteristics that arise both from the chemical diversity of peptides and the wide range of anionic species may contribute in a variety of output, including drug delivery, tissue engineering, gene transfection, and antibacterial activity. The emergent new phenomena and findings are illustrated. Finally, the outlook for the peptide-based ionic coassembly systems is also presented.

Ultrashort Peptide Self-Assembly: Front-Runners to Transport Drug and Gene Cargos

The translational therapies to promote interaction between cell and signal come with stringent eligibility criteria. The chemically defined, hierarchically organized, and simpler yet blessed with robust intermolecular association, the peptides, are privileged to make the cut-off for sensing the cell-signal for biologics delivery and tissue engineering. The signature service and insoluble network formation of the peptide self-assemblies as hydrogels have drawn a spell of research activity among the scientists all around the globe in the past decades. The therapeutic peptide market players are anticipating promising growth opportunities due to the ample technological advancements in this field. The presence of the other organic moieties, enzyme substrates and well-established protecting groups like Fmoc and Boc etc., bring the best of both worlds. Since the large sequences of peptides severely limit the purification and their isolation, this article reviews the account of last 5 years' efforts on novel approaches for formulation and development of single molecule amino acids, ultra-short peptide self-assemblies (di- and tri- peptides only) and their derivatives as drug/gene carriers and tissue-engineering systems.

Targeted delivery of microRNA-199a-3p using self-assembled dipeptide nanoparticles efficiently reduces hepatocellular carcinoma in mice

Hepatocellular carcinoma (HCC) is an aggressive tumor with limited systemic and locoregional modalities of treatment. Although microRNA (miRNA) based therapies have significant potential, their targeted delivery remains a major challenge. miR-199a-3p functions as an important tumor suppressor in HCC, which regulates various cellular processes. Recently, peptide-based nanoparticles (NPs) have been developed to deliver oligonucleotides including miRNA. Here, we describe the synthesis and characterization of arginine α,β-dehydrophenylalanine (RΔF) nanoparticles for the selective delivery of miR-199a-3p to restore dysregulated gene expression in HCC. Targeted delivery was achieved by conjugating lactobionic acid (LA) with RΔF NPs (RΔF-LA NPs), a ligand for the asialoglycoprotein receptor known to be overexpressed in HCC cell lines. RΔF-LA NPs condensed miR-199a-3p had an average size of ∼60nm and a zeta potential of ∼+2.54 mV. RΔF-LA/miR NPs were found to be stable in serum as well as against RNase attack. RΔF-LA/miR NPs showed an enhanced cellular uptake and an efficient delivery of miR-199a-3p leading to a significant increase in miR-199a-3p levels (over 500 fold). The increased miR-199a-3p levels remarkably suppressed cell proliferation and migration as well as induced cellular apoptosis and downregulation of the specific target gene (mTOR) in vitro. RΔF-LA/miR NPs showed high tumor/ low organ ratios after intravenous injection into HCC tumor bearing nude mice. RΔF-LA/miR NPs treated mice demonstrated>50% decline in tumor growth, which also corresponded well with suppression of mTOR protein expression, tumor cell proliferation and increased survival rate (P < 0.05).

CONCLUSION

RΔF-LA/miR NPs showed significantly enhanced delivery of the miRNA which underscores their potential for further development as a therapeutic approach for HCC. (Hepatology 2018;67:1392-1407).

Self-assembly of an amphipathic ααβ-tripeptide into cationic spherical particles for intracellular delivery

The development of molecular carriers able to carry molecules directly into the cell is an area of intensive research. Cationic nanoparticles are effective delivery systems for several classes of molecules, such as anticancer agents, oligonucleotides and antibodies. Indeed, a cationic charge on the outer surface allows a rapid cellular uptake together with the possibility of carrying negatively charged molecules. In this work, we studied the self-assembly of an ultra-short ααβ-tripeptide containing an l-Arg-l-Ala sequence and an unnatural fluorine substituted β^2,3-diaryl-amino acid. The presence of the unnatural β^2,3-diaryl-amino acid allowed us to obtain a protease stable sequence. Furthermore, an arginine guanidinium group triggered the formation of spherical assemblies that were able to load small molecules and enter cells. These spherical architectures, thus, represent interesting candidates for the delivery of exogenous entities directly into cells.

Arginine-α, β-dehydrophenylalanine Dipeptide Nanoparticles for pH-Responsive Drug Delivery

PURPOSE

Nanoparticles (NPs) exhibiting responsiveness towards pH variations in organs, tissue microenvironments and cellular compartments can significantly add on to the drug delivery potential. Here, we have developed NPs from an amphipathic dipeptide, Arginine-α, β-dehydrophenylalanine (RΔF), and tried to explore their pH responsive drug delivery potential in various cancer cells.

METHODS

RΔF-NPs were architectured by harnessing the process of molecular self-assembly followed by the assessment of effect of pH on NPs morphology using zetasizer, SEM and CD. FTIR and PXRD analysis of the dipeptide and doxorubicin (Dox) were carried out for compatibility assessment followed by encapsulation of Dox in RΔF-NPs. RΔF-Dox-NPs were evaluated for pH dependent release as well as for in-vitro cellular internalization and efficacy in cancer cells.

RESULTS

RΔF self-assembled to form monodispersed particles at pH 7. SEM analysis revealed a loss of overall particle morphology along with particle aggregation at highly acidic and basic pH respectively. The NPs demonstrated a slow and sustained release behaviour at pH 7 (97.64 ± 4.71% after 36 h) in comparison to pH 2 (90.27 ± 1.45% after 8 h) and pH 10 (96.39 ± 3.87% after 12 h). In-vitro efficacy studies carried-out in various cancer cells revealed that RΔF-Dox-NPs exhibited higher efficacy with 1.65, 1.95 and 13.34 fold lower IC₅₀ values in comparison to Dox in C6, HCT-116 and AGS cell lines.

CONCLUSIONS

RΔF-Dox-NPs with higher drug release at acidic pH, enhanced internalization in cancer cells along with higher cytotoxic potential can act as effective pH responsive drug delivery systems.

Target-specific delivery of siRNA into hepatoma cells' cytoplasm by bifunctional carrier peptide

RNA interference (RNAi) is among the most potential approach for the therapy of hepatocellular carcinoma and the major barrier hindering siRNA therapeutics is the low efficiency of delivery to the desired cells. The current study aimed at developing a novel peptide for more efficient hepatoma targeted siRNA delivery, by combining luteinizing hormone-releasing hormone with hepatoma targeting specificity and MPG^△NLS with cytoplasm-delivery tendency. The developed bifunctional peptide LHRH-MPG^△NLS and siRNA were mixed together and resulted in LHRH-MPG^△NLS/siRNA polyplexes through self-assembly. The polyplexes were characterized by agarose gel retardation and dynamic light scatting analysis. Hepatoma targeting specificity was analyzed with the GE IN Cell Analyzer 2000 High-Content Cellular Analysis System after cell transfection, and the effect of RNA interference was detected by RT-PCR. The results demonstrated that LHRH-MPG^△NLS was able to assemble with siRNA to form stable and nano-sized peptide/siRNA polyplexes, which could inhibit the expression of the target gene and was essentially non-cytotoxic, as compared with the commercial transfection reagent lipofectamine 2000.

Insight into the binding of a non-toxic, self-assembling aromatic tripeptide with ct-DNA: Spectroscopic and viscositic studies

The report describes the synthesis, self-association and DNA binding studies of an aromatic tripeptide H-Phe-Phe-Phe-OH (FFF). The peptide backbone adopts β-sheet conformation both in solid and solution. In aqueous solution, FFF self-assembles to form nanostructured aggregates. Interactions of this peptide with calf-thymus DNA (ct-DNA) have been studied using various biophysical techniques including ultraviolet (UV) absorption spectroscopy, fluorescence spectroscopy and circular dichroism (CD) spectroscopy. The value of mean binding constant calculated from UV and fluorescence spectroscopic data is (2.914 ± 0.74) x 103 M-1 which is consistent with an external binding mode. Fluorescence intercalator displacement (FID) assay, iodide quenching study, viscosity measurement and thermal denaturation study of DNA further confirm the groove binding mode of peptide, FFF with ct-DNA. MTT cell survival assay reveals very low cytotoxicity of the peptide toward human lung carcinoma cell line A549.

Nanoparticles generated from a tryptophan derivative: physical characterization and anti-cancer drug delivery

Surging reports of peptide-based nanosystems and their growing potency in terms of biological utility demand for the search of newer and simpler peptide-based systems that could serve as smart templates for the development of self-assembled nanostructures. Use of simple amino acids as monomeric building blocks for synthesizing ensembles of nanostructures have gained momentum in this direction with some reports focusing on the development of nanosystems from single or modified single amino acids. In this work, we have demonstrated self-assembly and nanoparticle formation ability of a single amino acid derivative, N-alpha-(9-fluorenylmethyloxycarbonyl)-N(in)-tert-butyloxycarbonyl-L-tryptophan [Fmoc-Trp(Boc)-OH]. The nanoparticles formed by the amino acid were found to be stable to various environmental perturbations like temperature, salts and showed responsiveness to pH change. These were capable of loading and releasing different bioactive molecules and were biocompatible. These systems demonstrated high cellular uptake and doxorubicin-loaded nanoparticles were found to be more efficient in killing glioma cells as compared to the drug alone. Thus, their simple amino acid-based origin along with the ability to ferry bioactive molecules to various cells, endows them the suitability for future applications in the field of drug delivery.

Recent advances in self-assembled peptides: Implications for targeted drug delivery and vaccine engineering

Self-assembled peptides have shown outstanding characteristics for vaccine delivery and drug targeting. Peptide molecules can be rationally designed to self-assemble into specific nanoarchitectures in response to changes in their assembly environment including: pH, temperature, ionic strength, and interactions between host (drug) and guest molecules. The resulting supramolecular nanostructures include nanovesicles, nanofibers, nanotubes, nanoribbons, and hydrogels and have a diverse range of mechanical and physicochemical properties. These molecules can be designed for cell-specific targeting by including adhesion ligands, receptor recognition ligands, or peptide-based antigens in their design, often in a multivalent display. Depending on their design, self-assembled peptide nanostructures have advantages in biocompatibility, stability against enzymatic degradation, encapsulation of hydrophobic drugs, sustained drug release, shear-thinning viscoelastic properties, and/or adjuvanting properties. These molecules can also act as intracellular transporters and respond to changes in the physiological environment. Furthermore, this class of materials has shown sequence- and structure-dependent impacts on the immune system that can be tailored to non-immunogenic for drug targeting, and immunogenic for vaccine delivery. This review explores self-assembled peptide nanostructures (beta sheets, alpha helices, peptide amphiphiles, amino acid pairing, elastin like polypeptides, cyclic peptides, short peptides, Fmoc peptides, and peptide hydrogels) and their application in vaccine delivery and drug targeting.

Efficient intravesical therapy of bladder cancer with cationic doxorubicin nanoassemblies

Nanoparticles have promising applications in drug delivery for cancer therapy. Herein, we prepared cationic 1,2-dioleoyl-3-trimethylammonium propane/methoxypoly (ethyleneglycol) (DPP) nanoparticles to deliver doxorubicin (Dox) for intravesical therapy of bladder cancer. The DPP micelles have a mean dynamic diameter of 18.65 nm and a mean zeta potential of +19.6 mV. The DPP micelles could prolong the residence of Dox in the bladder, enhance the penetration of Dox into the bladder wall, and improve cellular uptake of Dox. The encapsulation by DPP micelles significantly improved the anticancer effect of Dox against orthotopic bladder cancer in vivo. This work described a Dox-loaded DPP nanoparticle with potential applications in intravesical therapy of bladder cancer.

Short peptide based nanotubes capable of effective curcumin delivery for treating drug resistant malaria

Background

Curcumin (Ccm) has shown immense potential as an antimalarial agent; however its low solubility and less bioavailability attenuate the in vivo efficacy of this potent compound. In order to increase Ccm’s bioavailability, a number of organic/inorganic polymer based nanoparticles have been investigated. However, most of the present day nano based delivery systems pose a conundrum with respect to their complex synthesis procedures, poor in vivo stability and toxicity issues. Peptides due to their high biocompatibility could act as excellent materials for the synthesis of nanoparticulate drug delivery systems. Here, we have investigated dehydrophenylalanine (ΔPhe) di-peptide based self-assembled nanoparticles for the efficient delivery of Ccm as an antimalarial agent. The self-assembly and curcumin loading capacity of different ΔPhe dipeptides, phenylalanine–α,β-dehydrophenylalanine (FΔF), arginine-α,β-dehydrophenylalanine (RΔF), valine-α,β-dehydrophenylalanine (VΔF) and methonine-α,β-dehydrophenylalanine (MΔF) were investigated for achieving enhanced and effective delivery of the compound for potential anti-malarial therapy.

Results

FΔF, RΔF, VΔF and MΔF peptides formed different types of nanoparticles like nanotubes and nanovesicles under similar assembling conditions. Out of these, F∆F nanotubes showed maximum curcumin loading capacity of almost 68 % W/W. Ccm loaded F∆F nanotubes (Ccm-F∆F) showed comparatively higher (IC₅₀, 3.0 µM) inhibition of Plasmodium falciparum (Indo strain) as compared to free Ccm (IC₅₀, 13 µM). Ccm-F∆F nano formulation further demonstrated higher inhibition of parasite growth in malaria infected mice as compared to free Ccm. The dipeptide nanoparticles were highly biocompatible and didn’t show any toxic effect on mammalian cell lines and normal blood cells.

Conclusion

This work provides a proof of principle of using highly biocompatible short peptide based nanoparticles for entrapment and in vivo delivery of Ccm leading to an enhancement in its efficacy as an antimalarial agent.

In-vitro cytotoxicity assessment of carbon-nanodot-conjugated Fe-aminoclay (CD-FeAC) and its bio-imaging applications

We have investigated the cytotoxic assay of Fe-aminoclay (FeAC) nanoparticles (NPs) and simultaneous imaging in HeLa cells by photoluminescent carbon nanodots (CD) conjugation. Non-cytotoxic, photostable, and CD NPs are conjugated with cationic FeAC NPs where CD NPs play a role in bio-imaging and FeAC NPs act as a substrate for CD conjugation and help to uptake of NPs into cancer cells due to positively charged surface of FeAC NPs in physiological media. As increase of CD-FeAC NPs loading in HeLa cell in vitro, it showed slight cytotoxicity at 1000 μg/mL but no cytotoxicity for normal cells up to concentration of 1000 μg/mL confirmed by two 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red (NR) assays, with further observations by 4',6-diamidino-2-phenylindole (DAPI) stained confocal microscopy images, possessing that CD-FeAC NPs can be used as potential drug delivery platforms in cancer cells with simultaneous imaging. Graphical abstract CD conjugation with organo-building blocks of delaminated FeAC NPs.

Novel non-viral gene delivery systems composed of carbosilane dendron functionalized nanoparticles prepared from nano-emulsions as non-viral carriers for antisense oligonucleotides

The development of novel and efficient delivery systems is often the limiting step in fields such as antisense therapies. In this context, poly(d,l-lactide-co-glycolide) acid (PLGA) nanoparticles have been obtained by a versatile and simple technology based on nano-emulsion templating and low-energy emulsification methods, performed in mild conditions, providing good size control. O/W polymeric nano-emulsions were prepared by the phase inversion composition method at 25°C using the aqueous solution/polysorbate80/[4 wt% PLGA in ethyl acetate] system. Nano-emulsions formed at oil-to-surfactant (O/S) ratios between 10/90-90/10 and aqueous contents above 70 wt%. Nano-emulsion with 90 wt% of aqueous solution and O/S ratio of 70/30 was chosen for further studies, since they showed the appropriate characteristics to be used as nanoparticle template: hydrodynamic radii lower than 50 nm and enough kinetic stability. Nanoparticles, prepared from nano-emulsions by solvent evaporation, showed spherical shape, sizes about 40 nm, negative surface charges and high stability. The as-prepared nanoparticles were functionalized with carbosilane cationic dendrons through a carbodiimide-mediated reaction achieving positively charged surfaces. Antisense oligonucleotides were electrostatically attached to nanoparticles surface to perform gene-silencing studies. These complexes were non-haemolytic and non-cytotoxic at the concentrations required. The ability of the complexes to impart cellular uptake was also promising. Therefore, these novel nanoparticulate complexes might be considered as potential non-viral carriers in antisense therapy.

TAT-LHRH conjugated low molecular weight chitosan as a gene carrier specific for hepatocellular carcinoma cells

To develop a chitosan-based nonviral gene carrier capable of delivering genes specifically into hepatoma cells, a bifunctional peptide composed of the TAT (transactivator of transcription) peptide and luteinizing hormone-releasing hormone (LHRH) was conjugated with low molecular weight chitosan, resulting in a TAT-LHRH-chitosan conjugate (TLC). TLC/DNA nanoparticles (TLCDNPs) were characterized by agarose gel retardation, atomic force microscopy, and dynamic light scattering analysis. In vitro targeting specificity and transfection efficiency were analyzed with a GE IN Cell Analyzer 2000 High-Content Cellular Analysis System. The results demonstrated that TLC had stronger DNA condensing power than unmodified chitosan, and that TLCDNPs were of roughly round shape with average diameter of 70-85 nm and zeta potential of +30 mV and were relatively stable in solution. The in vitro study demonstrated TLC was highly selective for hepatoma cells and essentially nontoxic.

Short peptide based self-assembled nanostructures: implications in drug delivery and tissue engineering

Self-assembling peptides with many potential biomedical applications.