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The cell membrane is a highly selective barrier. This limits the cellular uptake of molecules including DNA, oligonucleotides, peptides and proteins used as therapeutic agents. Different approaches have been employed to increase the membrane permeability and intracellular delivery of these therapeutic molecules. One such approach is the use of Cell Penetrating Peptides (CPPs). CPPs represent a new and innovative concept, which bypasses the problem of bioavailability of drugs. The success of CPPs lies in their ability to unlock intracellular and even intranuclear targets for the delivery of agents ranging from peptides to antibodies and drug-loaded nanoparticles. This review highlights the development of cell penetrating peptides for cell-specific delivery strategies involving biomolecules that can be triggered spatially and temporally within a cell transport pathway by change in physiological conditions. The review also discusses conjugations of therapeutic agents to CPPs for enhanced intracellular delivery and bioavailability that are at the clinical stage of development.

Purpose: Lactoferrin (Lf), a mammalian cationic iron-binding glycoprotein belonging to the transferrin (Tf) family, has been widely used in a variety of fields ranging from treating infant diarrhea and supporting newborn growth to food and pharmaceutical applications. In this study, Lf nanoparticles were firstly used as carriers of gambogic acid (GA) to enhance oral absorption and anti-cancer activity, hence reducing the related toxic effect. Methods: Gambogic acid-lactoferrin nanoparticles (GL-NPs) were prepared by the nanoparticle albumin-bound (NAB) technology. The formed nanoparticles were characterized by DSC, TEM, etc. In situ intestinal perfusion experiment was performed to clarify the absorption mechanism of GL-NPs. Furthermore in vivo and in vitro anti-tumor activities of GL-NPs were also investigated. Results: GL-NPs was successfully prepared with about 150 nm mean size, þ20 mV z potential, 92.3 AE 7.2% encapsulation efficiency and 9.04 AE 0.7% DL; GL-NPs also exhibited a better stability and a desirable slow release in vitro experiment. The results of in situ intestinal perfusion showed a transformation of GA absorption from passive diffusion into active transport or facilitated diffusion by GL-NPs. MTT assay of GL-NPs showed almost an equal antiproliferative effect with arginine solution of GA (Arg-GA) in HepG2 cell. The inhibitory rate against S180 tumor mice after oral administration of GL-NPs was up to 86.01% which was1.39-folds of intravenous injection of Arg-GA. Conclusion: The in vitro results showed that the NAB technology was feasible for industrial production of Lf nanoparticles and the in vivo results proved that the effective GL-NPs is a promising approach for the oral delivery of GA. These obtained research works have also paved the preliminary way for the study of Lf as an oral drug delivery carrier.

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OACS provided excellent ability of drug loading, increasing solubility and enhanced absorption for GA, which indicated that OACS micelles as an oral drug delivery carrier may have potential research and application values.

The purpose of this research was to prepare floating calcium alginate beads of berberine for targeting the gastric mucosa and prolonging their gastric residence time. The floating beads were prepared by suspending octodecanol and berberine in sodium alginate (SA) solution. The suspension was then dripped into a solution of calcium chloride. The hydrophobic and low-density octodecanol enhanced the sustained-release properties and floating ability of the beads. The bead formulation was optimized for different weight ratios of octodecanol and SA and evaluated in terms of diameter, floating ability and drug loading, entrapment and release. In vitro release studies showed that the floating and sustained release time were effectively increased in gastric media by addition of octodecanol. In vivo studies with rats showed that a significant increase in gastric residence time of beads had been achieved.

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Mixed micelles were designed to increase oral bioavailability of Apigenin (Ap). The phospholipid (Ph) complex technology was exploited alongside TPGS' stabilizing effect by PEG chain sterical hindrance of the phase II enzymes. This prevented extensive metabolism of Ap while inhibiting P-glycoprotein's exocytosis. TPGS modified micelles of Ap-Ph complex (TPGS-Ap-Ph) were prepared by thin film hydration method. Ap-Ph complex was confirmed by FTIR and NMR spectroscopy while Ap, Ph and TPGS interactions were studied by surface tensiometry. TPGS-Ap-Ph micelles achieved 87.35% drug encapsulation and 12.6% drug loading showing spherical morphology 137.1 +/- 3.4 nm particle size and -12.94 mV surface charge. The negative zeta potential confirmed computer simulation predictions that PEG moieties of TPGS were at micelles surface, while hydrophobic part inserted to the phospholipid hydrophobic core by electrostatic interactions. TPGS-Ap-Ph micelles were found to be stable for more than 90 days after lyophilization. Comparing to free drug, the micelles increased intestinal absorption of Ap 2.4 fold, illustrating apparent permeation (P(app)) and absorption constant (K(a)) of 7.9 x 10(-4) and 2.05 x 10(-4) (p < 0.001) respectively. Moreover, cell culture studies showed high cellular uptake with sufficient intracellular trafficking in A549 cells. MTT assays revealed a significant cytotoxic effect by TPGS-Ap-Ph micelles. In vivo, an effective inhibition of 72.9% was achieved upon oral administration to S180 carcinoma mice compared to 19.5% by Ap-Ph complex. Altogether reflect that orally administered mixed micelles of TPGS-Ap-Ph could effectively inhibit cancer. The results present the designed micelles as a new way to improve oral bioavailability of sparingly soluble and poorly absorbed drugs.