Tf ligand-receptor-mediated exenatide-Zn2+ complex oral-delivery system for penetration enhancement of exenatide

Safe and effective oral delivery of peptide is a challenge. Here, we used exenatide and zinc ions (Zn²⁺) to form a complex to explore a meaningful oral-targeted drug-delivery system. Polyethylene glycol-poly(lactic acid-co-glycolic acid) (PEG-PLGA) was used to prepare nanoparticles (NPs) to escape the degradation caused by gastrointestinal enzymes. Transferrin (Tf) was used as a targeting group. PEG-PLGA-NPs and Tf-modified exenatide-Zn²⁺-loaded NPs (Tf-PEG-PLGA-NPs) were uniformly sized spheres according to transmission electron microscopy. The results of pharmacodynamic and pharmacokinetic investigations in vivo were consistent with in vitro studies using Caco-2 cells. Tf enhanced NPs transport in cell-uptake and transmembrane-transport experiments. Our results showed that the relative bioavailability of Tf-exenatide-Zn²⁺-NPs was higher than that of exenatide-Zn²⁺-NPs. The relative bioavailability of Tf-exenatide-Zn²⁺-NPs versus subcutaneous injection of exenatide was 6.45%. This was a preliminary exploration of the oral administration of exenatide, that data from which can be used for future investigations.     

Modified mixed nanomicelles with collagen peptides enhanced oral absorption of Cucurbitacin B: preparation and evaluation

Polymer nanoparticles modified with collagen peptides (CPs) are an attractive strategy for the oral delivery of active ingredients from Chinese medicine. Thus, in the present study, collagen cationic CPs were simply separated using ion-exchange resin from bovine CPs, to modify mixed nanomicelles (MMs) on the surface to improve the oral bioavailability of Cucurbitacin B (CuB). The physicochemical property of micelles was characterized, which confirmed the successful modification of the nanomicelles. CPs-modified nanomicelles in vitro were found to significantly increase cellular uptake and transportation. Compared to unmodified micelles, the quantity of CPs-modified micelles internalized by Caco-2 cells were 3.74 times greater and the cumulative transportation flux (AP-BL) was 2.81 times greater. The membrane transportation process of CuB-MMs-CPs was found to be associated with energy consumption and clathrin- and caveolin-mediated endocytosis. In vivo studies performed on rats indicated that in comparison to CuB and CuB-MMs, the relative bioavailability of CuB-MMs-CPs increased by 3.43 times and 2.14 times, respectively. In addition, the tumor inhibition caused by CuB-MMs-CPs was increased significantly. Therefore, the nanomicelles co-modified with isolated CPs could act as attractive carriers for oral delivery of CuB.     

Oligoarginine-modified biodegradable nanoparticles improve the intestinal absorption of insulin

The strategy of oral administration of bioactive macromolecules using cell-penetrating peptides (CPPs) is restricted to covalent linkage or electrostatic interaction between the cargo and CPPs. In the present study, we devised an approach utilizing CPP-functionalized poly(lactic-co-glycolic acid) (PLGA) nanoparticles as a carrier for oral delivery of insulin. Pegylated PLGA nanoparticles were modified with poly(arginine)₈ enantiomers (l-R8 and d-R8) via a maleimide-mediated covalent conjugating procedure. The physical and chemical features of the nanoparticles were characterized, which confirmed the successful immobilization of R8 to the nanoparticles. Using a Caco-2 cell monolayer model, R8-modified nanoparticles were found to exhibit significantly increased cellular uptake and transportation. Pharmacokinetics and pharmacodynamics of the insulin-loaded nanoparticles were evaluated with rats by intestinal administration. Compared to the unmodified nanoparticles, l-R8 and d-R8 modified-nanoparticles increased the relative bioavailabilities of insulin by 3.2- and 4.4-times, meanwhile, improved the hypoglycemic effects by 2.5- and 3.7-times, respectively. Neither of the R8-modified nanoparticles caused perceptible histological toxicities. The results implied that surface modification of biodegradable nanoparticles with poly(arginine)₈, especially with the d-form enantiomer, showed remarkable advancement in promoting the intestinal absorption of insulin. This delivery system is also promising for the delivery of a wide variety of bioactive macromolecules by oral administration.     

Region-Dependent Role of Cell-Penetrating Peptides in Insulin Absorption Across the Rat Small Intestinal Membrane

We have reported that the cell-penetrating peptide (CPP) penetratin acts as a potential absorption enhancer in oral insulin delivery systems and that this action occurs through noncovalent intermolecular interactions. However, the region-dependent role of CPPs in intestinal insulin absorption has not been clarified. To identify the intestinal region where CPPs have the most effect in increasing insulin absorption, the region-dependent action of penetratin was investigated using in situ closed intestinal loops in rats. The order of the insulin area under the insulin concentration–time curve (AUC) increase effect by l-penetratin was ileum > jejunum > duodenum > colon. By contrast, the AUC order after coadministration of insulin with d-penetratin was colon > duodenum ≥ jejunum and ileum. We also compared the effects of the l- and d-forms of penetratin, R8, and PenetraMax on ileal insulin absorption. Along with the CPPs used in this study, l- and d-PenetraMax produced the largest insulin AUCs. An absorption study using ilea pretreated with CPPs showed that PenetraMax had no irreversible effect on the intestinal epithelial membrane. The degradation of insulin in the presence of CPPs was assessed in rat intestinal enzymatic fluid. The half-life (t_1/2) of insulin increased from 14.5 to 23.7 and 184.7 min in the presence of l- and d-PenetraMax, respectively. These enzymatic degradation-resistant effects might contribute partly to the increased ileal absorption of insulin induced by d-PenetraMax. In conclusion, this study demonstrated that the ability of the l- and d-forms of penetratin to increase intestinal insulin absorption was maximal in the ileum and the colon, respectively, and that d-PenetraMax is a powerful but transient enhancer of oral insulin absorption.KEY WORDS: absorption enhancement, cell-penetrating peptide, enzymatic degradation, insulin, intestinal membrane     

A detachable coating of cholesterol-anchored PEG improves tumor targeting of cell-penetrating peptide-modified liposomes

Cell-penetrating peptides (CPPs) have been widely used to enhance the membrane translocation of various carriers for many years, but the non-specificity of CPPs seriously limits their utility in vivo. In this study, cholesterol-anchored, reduction-sensitive PEG (first synthesized by our laboratory) was applied to develop a co-modified liposome with improved tumor targeting. Following optimization of the formulation, the in vitro and in vivo properties of the co-modified liposome were evaluated. The co-modified liposome had a much lower cellular uptake and tumor spheroid uptake, but a much higher tumor accumulation compared to CPP-modified liposome, indicating the non-specific penetration of CPPs could be attenuated by the outer PEG coating. With the addition of exogenous reducing agent, both the in vitro and in vivo cellular uptake was markedly increased, demonstrating that the reduction-sensitive PEG coating achieved a controllable detachment from the surface of liposomes and did not affect the penetrating abilities of CPPs. The present results demonstrate that the combination of cholestervsitive PEG and CPPs is an ideal alternative for the application of CPP-modified carriers in vivo.KEY WORDS: Cell penetrating peptide, Reduction-sensitive PEG, Tumor targeting, Cholesterol, Liposome     

Multifunctional targeted therapy system based on 99mTc/177Lu‐labeled gold nanoparticles‐Tat(49–57)‐Lys3‐bombesin internalized in nuclei of prostate cancer cells

Radiolabeled gold nanoparticles may function simultaneously as radiotherapy and thermal ablation systems. The gastrin‐releasing peptide receptor (GRP‐r) is overexpressed in prostate cancer, and Lys³‐bombesin is a peptide that binds with high affinity to the GRP‐r. HIV Tat(49–57) is a cell‐penetrating peptide that reaches the DNA. In cancer cells, ¹⁷⁷Lu shows efficient crossfire effect, whereas ^99mTc that is internalized in the cancer cell nuclei acts as an effective system of targeted radiotherapy because of the biological Auger effect. The aim of this research was to evaluate the in vitro potential of ^99mTc‐labeled and ¹⁷⁷Lu‐labeled gold nanoparticles conjugated to Tat(49–57)‐Lys³‐bombesin peptides (^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN) as a plasmonic photothermal therapy and targeted radiotherapy system in PC3 prostate cancer cells. Peptides were conjugated to AuNPs (5 nm) by spontaneous reaction with the thiol group of cysteine (Cys). The effect on PC3 cell viability after laser heating of the AuNP‐Tat‐BN incubated with the cancer cells was conducted using an Nd:YAG laser pulsed for 5 ns at 532 nm (0.65 W/cm²). For the ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN to be obtained, the ¹⁷⁷Lu‐DOTA‐Gly‐Gly‐Cys and ^99mTc‐HYNIC‐octreotide radiopeptides were first prepared and added simultaneously to a solution of AuNP‐Tat‐BN. ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN (20 Bq/cell) was incubated with PC3 cells, and the effect on the cell proliferation was evaluated after 3 days. Fluorescence images of ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN internalized in nuclei of PC3 were also obtained. After laser irradiation, the presence of AuNP‐Tat‐BN caused a significant increase in the temperature of the medium (46.4 vs 39.5 °C of that without AuNP) resulting in a significant decrease in PC3 cell viability down to 1.3%. After treatment with ^99mTc/¹⁷⁷Lu‐AuNP‐Tat‐BN, the PC3 cell proliferation was inhibited. The nanosystem exhibited properties suitable for plasmonic photothermal therapy and targeted radiotherapy in the treatment of prostate cancer.     

Design of Estradiol Loaded PLGA Nanoparticulate Formulations: A Potential Oral Delivery System for Hormone Therapy

Abstract Estradiol (E2), a highly lipophilic molecule with good oral absorption but poor oral bioavailability, was incorporated into poly(lactide-co-glycolide) (PLGA) nanoparticles to improve its oral bioavailability. Nanoparticles were prepared by using polyvinyl alcohol (PVA) or didodecyldimethylammonium bromide (DMAB) as stabilizer, leading to negatively (size 410.9 ± 39.4 nm) and positively (size 148.3 ± 10.7 nm) charged particles, respectively. Both preparations showed near zero order release in vitro with about 95% drug being released within 45 and 31 days for PVA and DMAB, respectively. In situ intestinal uptake studies in male Sprague–Dawley (SD) rats showed higher uptake of DMAB stabilized nanoparticles. Following oral administration to male SD rats, E2 could be detected in blood for 7 and 2 days from DMAB and PVA stabilized nanoparticles, respectively. Histopathological examination and blood counts indicated the absence of inflammatory response. These data suggest that DMAB stabilized PLGA nanoparticles have great potential as carriers for oral delivery of estradiol.     

寡聚精氨酸促进胰岛素纳米粒肠道吸收

探索一种穿膜肽寡聚精氨酸[poly(arginine)8,R8]修饰的可生物降解乳酸/羟基乙酸共聚物[poly(lactic-co-glycolic acid),PLGA]纳米粒作为胰岛素(insulin,INS)口服给药载体的可行性。采用复乳-溶剂挥发法制备包载胰岛素的PLGA纳米粒(INS-NP),R8经聚乙二醇桥联修饰于该纳米粒表面(R8-INS-NP)。对纳米粒进行理化性状表征及体外释放特性考察,并进行正常大鼠在体灌肠给药的药动学与药效学评价。所得纳米粒平均粒径为(179.0±5.2)nm,多分散系数为0.152±0.042,胰岛素包封率为(29.10±2.59)%,载药量为(5.05±0.50)%,体外释放呈先快后慢的两相模式。给药剂量为10 U.kg—1时,R8-INS-NP的降血糖效果显著优于同剂量的INS-NP,而且D-构型R8修饰的纳米粒(D-R8-INS-NP)吸收优于L-构型R8修饰的纳米粒(L-R8-INS-NP)。与皮下注射相比,INS-NP、L-R8-INS-NP和D-R8-INS-NP在体灌肠给药的相对生物利用度分别为0.52%、4.78%和8.39%,药理相对生物利用度分别为2.07%、3.90%和8.24%。纳米粒表面经R8修饰可促进其包载的胰岛素经肠道吸收,为实现多肽、蛋白类生物大分子口服给药提供了新思路。     

Synergistic effects of cell-penetrating peptide Tat and fusogenic peptide HA2-enhanced cellular internalization and gene transduction of organosilica nanoparticles

The nonviral gene delivery system is an attractive alternative to cancer therapy. A new kind of gelatin-silica nanoparticles (GSNPs) was developed through a two-step sol-gel procedure. To improve the transfection efficacy, GSNPs modified with different fusion peptides (Tat, HA2, R8, Tat/HA2, and Tat/R8) were prepared for particle size, zeta potential, cellular uptake, hemolysis activity at physiological pH (7.0) or acidic pH (5.0), and condensation of plasmid DNA. The results suggest that the sizes and zeta potentials of GS-peptide conjugates were 147 - 161 nm and 19 - 33 mV, respectively; GS-peptide conjugates exhibited low cytotoxicity; the plasmid DNA was readily entrapped at a GS-peptide/pDNA weight ratio of 50 - 200. The in vitro and in vivo studies demonstrated that the synergistic effects of cell-penetrating peptide Tat and fusogenic peptide HA2 could promote the efficient cellular internalization, endosome escape, and nucleus targeting, hence delivering the therapeutic nucleic acid efficiently.     

The role of chitosan on oral delivery of peptide-loaded nanoparticle formulation

Therapeutic peptides are conventionally administered via subcutaneous injection. Chitosan-based nanoparticles are gaining increased attention for their ability to serve as a carrier for oral delivery of peptides and vaccination. They offered superior biocompatibiltiy, controlled drug release profile and facilitated gastrointestinal (GI) absorption. The encapsulated peptides can withstand enzymatic degradation and various pH. Chitosan-based nanoparticles can also be modified by ligand conjugation to the surface of nanoparticle for transcellular absorption and specific-targeted delivery of macromolecules to the tissue of interest. Current research suggests that chitosan-based nanoparticles can deliver therapeutic peptide for the treatment of several medical conditions such as diabetes, bacterial infection and cancer. This review summarises the role of chitosan in oral nanoparticle delivery and identifies the clinical application of peptide-loaded chitosan-based nanoparticles.     

Penetratin-Mediated Transepithelial Insulin Permeation: Importance of Cationic Residues and pH for Complexation and Permeation

Penetratin is a widely used carrier peptide showing promising potential for mucosal delivery of therapeutic proteins. In the present study, the importance of specific penetratin residues and pH was investigated with respect to complexation with insulin and subsequent transepithelial insulin permeation. Besides penetratin, three analogues were studied. The carrier peptide-insulin complexes were characterized in terms of size and morphology at pH 5, 6.5, and 7.4 by dynamic light scattering (DLS) and transmission electron microscopy (TEM), respectively. At pH 7.4 mainly very large complexes were present, while much smaller complexes dominated at pH 5. Presence of arginine residues in the carrier peptide proved to be a prerequisite for complexation with insulin as well as for enhanced transepithelial insulin permeation in vitro. Rearrangement of tryptophan residues resulted in significantly increased insulin permeation as compared to that of the parent penetratin. In general, pre-complexation with penetratin and its analogues at pH 5 gave rise to increased insulin permeation as compared to that observed at pH 7.4; this finding was further supported by a preliminary in vivo study using the parent penetratin.

Electronic supplementary material

The online version of this article (doi:10.1208/s12248-015-9747-3) contains supplementary material, which is available to authorized users.KEY WORDS: Caco-2 cell culture model, carrier peptide, insulin, penetratin, transepithelial permeation     

Investigation of lectin-modified insulin liposomes as carriers for oral administration

The aim of this study was to design and characterize lectin-modified liposomes containing insulin and to evaluate the potential of these modified colloidal carriers for oral administration of peptide and protein drugs. Wheat germ agglutinin (WGA), tomato lectin (TL), or Ulex europaeus agglutinin 1 (UEA1) were conjugated by coupling their amino groups to carbodiimide-activated carboxylic groups of N-glutaryl-phosphatidylethanolamine (N-glut-PE). Insulin liposomes dispersions were prepared by the reverse-phase evaporation technique and modified with the lectin-N-glut-PE conjugates. Lectin-modified liposomes were characterized according to particles size, zeta potential and entrapment efficiency. The hypoglycemic effect indicated by pharmacological bioavailability of insulin liposomes modified with WGA, TL and UEA1 were 21.40, 16.71 and 8.38% in diabetic mice as comparison with abdominal cavity injection of insulin, respectively. After oral administration of the insulin liposomes modified with WGA, TL and UEA1 to rats, the relative pharmacological bioavailabilities were 8.47, 7.29 and 4.85%, the relative bioavailability were 9.12, 7.89 and 5.37% in comparison with subcutaneous injection of insulin, respectively. In the two cases, no remarkable hypoglycemic effects were observed with the conventional insulin liposomes. These results confirmed that lectin-modified liposomes promote the oral absorption of insulin due to the specific-site combination on GI cell membrane.     

Antimicrobial and Cytolytic Activities and Plausible Mode of Bactericidal Action of the Cell Penetrating Peptide Penetratin and Its Lys‐linked Two‐Stranded Peptide

The cell penetrating peptide, penetratin (RQIKIWFQNRRMKWKK‐NH₂) showed potent antimicrobial activity (MIC: 0.5–4 μm ) without any cytotoxicity against mammalian cells. This study investigated the effect of linking together two peptide chains of penetratin on antimicrobial and cytolytic activities and plausible mode of bactericidal action. Two‐stranded penetratin was prepared by a simultaneous solid‐phase synthesis of the two strands of a single lysine residue attached to the solid support. Two‐stranded penetratin markedly increased cytolytic activity against human erythrocytes and NIH‐3T3 mouse fibroblast cells without a significant effect on antimicrobial activity. This finding suggested that penetratin is active as a monomer to bacterial cells but as an oligomer to mammalian cells. Circular dichroism analysis revealed that the α‐helical content of the membrane‐bound penetratin was unaffected by two‐stranded Lys‐linkage. Penetratin had very weak ability in the depolarization of membrane potential of intact Staphylococcus aureus cells and the fluorescent dye leakage of calcein‐entrapped negatively charged bacterial membrane‐mimicking vesicles. In contrast, two‐stranded penetratin significantly caused membrane depolarization and dye leakage. These results suggest that the two‐stranded penetratin induces a significant change in its mode of bactericidal action from the intracellular‐target mechanism to the membrane‐targeting mechanism.     

Effects of Non-Covalent Self-Association on the Subcutaneous Absorption of a Therapeutic Peptide

Purpose. To utilize an acylated peptide as a model system to investigate the relationships among solution peptide conformation, non-covalent self-association, subcutaneous absorption and bioavailability under pharmaceutically relevant solution formulation conditions. Methods. CD spectroscopy, FTIR spectroscopy, equilibrium sedimentation, dynamic light scattering, and size exclusion chromatography were employed to characterize the effects of octanoylation on conformation and self-association of the 31 amino acid peptide derivative des-amino-histidine(7) arginine(26) human glucagon-like peptide (7-37)-OH (IP(7)R(26)GLP-1). Hyperglycemic clamp studies were performed to compare the bioavailability, pharmacokinetics, and pharmacodynamics of solution formulations of oct-IP(7)R(26)GLP-l administered subcutaneously to normal dogs. Results. Octanoylation of IP(7)R(26)GLP-1 was shown to confer the propensity for a major solvent-induced conformational transition with an accompanying solvent- and temperature-dependent self-association behavior. Formulations were characterized that give rise to remarkably different pharmacodynamics and pharmacokinetics that correlate with distinct peptide conformational and self-association states. These states correspond to: (i) a minimally associated -helical form (apparent molecular weight = 14 kDa), (ii) a highly associated, predominantly -sheet form (effective molecular diameter 20 nm), and (iii) an unusually large, micelle-like soluble -sheet aggregate (effective molecular diameter 50 nm). Conclusions. Bioavailability and pharmacokinetics of a self-associating peptide can be influenced by aggregate size and the ease of disruption of the non-covalent intermolecular interactions at the subcutaneous site. Hydrophobic aggregation mediated by seemingly innocuous solution formulation conditions can have a dramatic effect on the subcutaneous bioavailability and pharmacokinetics of a therapeutic peptide and in the extreme, can totally preclude its absorption. A size exclusion chromatographic method is identified that distinguishes subcutaneously bioavailable aggregated oct-IP(7)R(26)GLP-1 from non-bioavailable aggregated oct-IP(7)R(26)GLP-1.     

Effect of different intestinal conditions on the intermolecular interaction between insulin and cell-penetrating peptide penetratin and on its contribution to stimulation of permeation through intestinal epithelium

Our recent studies have shown that the coadministration of cell-penetrating peptides (CPPs) is a potential strategy for oral delivery of peptide- and protein-based biopharmaceuticals. The intermolecular interaction between drug and CPP is an essential factor in the effective delivery of these drugs, but the characteristics of the interaction under the conditions of the intestinal lumen remain unknown. In this study, therefore, we examined the characteristics of binding of the amphipathic CPP penetratin to insulin and the efficiency of its enhancement of epithelial insulin transport at different pH and in simulated intestinal fluids (SIFs). The binding between insulin and penetratin was pH dependent and particularly decreased at pH 5.0. In addition, we clarified that the sodium taurocholate (NaTC) present in two types of SIF (fasted-state SIF [FaSSIF] and fed-state SIF [FeSSIF]) affected binding efficiency. However, the permeation of insulin through a Caco-2 cell monolayer was significantly facilitated by coincubation with l- or d-penetratin at various pH values. Moreover, the permeation-stimulating effect of l-penetratin was observed in FaSSIF containing NaTC and lecithin, but not in 3 mM NaTC solution, suggesting that the presence of lecithin was the key factor in maintaining the ability of penetratin to enhance the intestinal absorption of biopharmaceuticals. This report describes the essential considerations for in vivo use and clinical application of a CPP-based oral delivery strategy.     

Chitosan Reduced Gold Nanoparticles as Novel Carriers for Transmucosal Delivery of Insulin

Purpose Colloidal metallic systems have been recently investigated in the area of nanomedicine. Gold nanoparticles have found themselves useful for diagnostic and drug delivery applications. Herein we have reported a novel method for synthesis of gold nanoparticles using a natural, biocompatible and biodegradable polymer; chitosan. Use of chitosan serves dual purpose by acting as a reducing agent in the synthesis of gold nanoparticles and also promotes the penetration and uptake of peptide hormone insulin across the mucosa. To demonstrate the use of chitosan reduced gold nanoparticles as carriers for drug delivery, we report herein the transmucosal delivery of insulin loaded gold nanoparticles. Materials and Methods Gold nanoparticles were prepared using different concentrations of chitosan (from 0.01% w/v up to 1% w/v). The gold nanoparticles were characterized for surface plasmon band, zeta potential, surface morphology, in vitro diffusion studies and fluorescence spectroscopy. The in vivo studies in diabetic male Wistar rats were carried out using insulin loaded chitosan reduced gold nanoparticles. Results Varying concentrations of chitosan used for the synthesis of gold nanoparticles demonstrated that the nanoparticles obtained at higher chitosan concentrations (>0.1% w/v) were stable showing no signs of aggregation. The nanoparticles also showed long term stability in terms of aggregation for about 6 months. Insulin loading of 53% was obtained and found to be stable after loading. Blood glucose lowering at the end of 2 h following administration of insulin loaded gold nanoparticles to diabetic rats was found to be 30.41 and 20.27% for oral (50 IU/kg) and nasal (10 IU/kg), respectively. Serum gold level studies have demonstrated significant improvement in the uptake of chitosan reduced gold nanoparticles. Conclusions The synthesis of gold nanoparticles using a biocompatible polymer, chitosan would improve its surface properties for binding of biomolecules. Our studies indicate that oral and nasal administration of insulin loaded chitosan reduced gold nanoparticles has led to improved pharmacodynamic activity. Thus, chitosan reduced gold nanoparticles loaded with insulin prove to be promising in controlling the postprandial hyperglycemia.     

Nanostructured lipid (NLCs) carriers as a bioavailability enhancement tool for oral administration

ABSTRACT

Context: Nanostructured lipid carrier (NLCs) is the second generation solid lipid nanoparticles (NPs) made up of physiological, biocompatible, biodegradable, non-sensitizing and non-irritating lipids.

Objective: The main objective of this review is to explore the role of NLCs system for delivering drugs by oral route and thus increasing the oral bioavailability.

Methods: The present review article highlights the definition and types of NLCs and their importance as colloidal carriers including the production techniques and their formulation. This review article also deals with the fate of lipids used in the NLCs formulation and the NLCs toxicity.

Conclusion: On the basis of the literature survey done, it was concluded that the NLCs enhances the oral bioavailability of the drug and may decrease the side effects and toxicity of the lipids used in other polymeric NPs as NLCs uses physiological and biodegradable lipids.     

A modified Tat peptide for selective intracellular delivery of macromolecules

Objectives The Tat peptide has been widely used for the intracellular delivery of macromolecules. The aim of this study was to modify the peptide to enable regulation of cellular uptake through a dependency on activation by proteases present in the local environment. Methods The native Tat peptide sequence was altered to inhibit the initial interaction of the peptide with the cell membrane through the addition of the consensus sequence for urokinase plasminogen activator (uPA). uPA expression was characterised and semi‐quantitatively rated in three cell lines (U251mg, MDA‐MB‐231 and HeLa). The modified peptide was incubated with both recombinant enzyme and with cells varying in uPA activity. Cellular uptake of the modified Tat peptide line was compared with that of the native peptide and rated according to uPA activity measured in each cell line. Key findings uPA activity was observed to be high in U251mg and MDA‐MB‐231 and low in HeLa. In MDA‐MB‐231 and HeLa, uptake of the modified peptide correlated with the level of uPA expression detected (93 and 52%, respectively). In U251mg, however, the uptake of the modified peptide was much less (19% observed reduction) than the native peptide despite a high level of uPA activity detected. Conclusions Proteolytic activation represents an interesting strategy for the targeted delivery of macromolecules using peptide‐based carriers and holds significant potential for further exploitation.     

Bovine serum albumin nanoparticles improve the antitumour activity of curcumin in a murine melanoma model

Abstract

Curcumin is a natural compound presenting important antitumour activity. However, due to its low aqueous solubility, instability at physiological pH, and low oral bioavailability, its clinical use is limited. Bovine serum albumin (BSA) nanoparticles have been used as drug carriers to improve the drug properties. In this work, curcumin-loaded BSA nanoparticles were developed and the in vitro cytotoxicity over murine melanoma cells and the in vivo antitumour activity in a murine melanoma model were assessed. Nanoparticles presented 150?nm, polydispersity index of 0.16, negative zeta potential, and 45% of curcumin encapsulation efficiency. Curcumin release from nanoparticles was slow and diffusion dependent. In the cytotoxicity assay, free curcumin was more efficient than curcumin-loaded nanoparticles, probably due to the prolonged curcumin release from nanoparticles. However, in a murine melanoma model, curcumin-loaded nanoparticles presented higher antitumour efficiency than free curcumin. BSA nanoparticles are efficient curcumin carriers that may have relevant applications in melanoma treatment.