Cell-penetrating peptide-functionalized quantum dots for intracellular delivery

Experimental Evaluation of Quantum Dots and Antibodies Conjugation by Surface Plasmon Resonance Spectroscopy

The application of antibody-functionalized quantum dots (QDs) in different areas has been widely described in the literature. However, a standard routine method for obtaining information on the conjugation efficiency of QDs with antibodies in terms of the interaction of the functionalized QDs with a specific antigen is still lacking. Herein, surface plasmon resonance (SPR) spectroscopy is proposed for this purpose. Gold-coated SPR sensor disks were modified with a self-assembled monolayer of 11-mercaptoundecanoic acid, and carbodiimide cross-linker chemistry was used to covalently immobilize the CD44 biomarker on the premodified surface (Au/CD44). Meanwhile, QDs functionalized with amine-derivatized polyethylene glycol (PEG) (QDs-NH₂) were chosen for conjugation with antibodies because of their low non-specific adsorption on the Au/CD44 surface. Prior to conjugation, the surface binding capacity (B_max) and equilibrium dissociation constant (K_D) of the specific antibodies against CD44 (anti-CD44) were found to be 263.32 ± 2.44 m° and 1.00 × 10⁻⁷ ± 2.29 × 10⁻⁹ M, respectively. QDs-NH₂ and anti-CD44 were conjugated at their initial molar ratios of 1:3, 1:5, 1:10 and 1:12. SPR measurements showed that the conjugates (QDs-anti-CD44) prepared using 1:10 and 1:12 molar ratios interacted comparably with immobilized CD44 biomarkers. The equilibrium angles in the case of 10- and 12-fold concentrations of anti-CD44 were calculated to be 60.43 ± 4.51 and 61.36 ± 4.40 m°, respectively. This could be explained by the QDs-NH₂ and anti-CD44 having a similar surface loading (about four molecules per QDs-NH₂) and similar hydrodynamic diameters, which were 46.63 ± 3.86 and 42.42 ± 0.80 nm for the 1:10 and 1:12 ratios, respectively. An initial QDs-NH₂: anti-CD44 molar ratio of 1:10 was chosen as being optimal. SPR spectroscopy proved to be the right choice for QDs-anti-CD44 conjugation optimization, and can be used for the evaluation of conjugation efficiency for other nanostructures with various bio-recognition molecules.

Fluorescent Polymerase Chain Reaction Nanokit for the Detection of DNA Sequence in Single Living Cells

Here, a fluorescent polymerase chain reaction (PCR) nanokit is established to detect the specific DNA sequence in a single living cell. Different from well-developed protocols to load cell-permeable probes into single cell for recognition, the DNA sequence in a cellular nucleus is sorted into a nanopipette in our strategy. The target DNA sequence is reacted with the PCR kit components in the nanopipette to complete a PCR amplification reaction. SYBR Green prefilled in the nanopipette is intercalated into double-stranded DNA to induce fluorescence emission for real-time detection down to a single copy. An obvious increase in the fluorescence is observed that validates the detection of the target DNA sequence in single living cells. The established real-time fluorescent PCR nanokit could adapt the PCR kit for single cell analysis and thus offers an alternatively general and highly sensitive strategy for the detection of specific DNA sequences in single living cells.

Cell-Penetrating Peptides as a Potential Drug Delivery System for Effective Treatment of Diabetes

BACKGROUND/PURPOSE

Type 2 diabetes (T2D) is characterized by hyperglycemia resulting from the body's inability to produce and/or use insulin. Patients with T2D often have hyperinsulinemia, dyslipidemia, inflammation, and oxidative stress, which then lead to hypertension, chronic kidney disease, cardiovascular disease, and increased risk of morbidity and mortality (9th leading cause globally). Insulin and related pharmacological therapies are widely used to manage T2D, despite their limitations. Efficient drug delivery systems (DDS) that control drug kinetics may decrease side effects, allow for efficient targeting, and increase the bioavailability of drugs to achieve maximum therapeutic benefits. Thus, the development of effective DDS is crucial to beat diabetes.

METHODS

Here, we introduced a highly bioavailable vector, cell-penetrating peptides (CPPs), as a powerful DDS to overcome limitations of free drug administration.

RESULTS

CPPs are short peptides that serve as a potent tool for delivering therapeutic agents across cell membranes. Various cargoes, including proteins, DNA, RNA, liposomes, therapeutic molecules, and nanomaterials, generally retain their bioactivity upon entering cells. The mechanisms of CPPs/cargoes intracellular entry are classified into two parts: endocytic pathways and direct membrane translocation. In this article, we focus on the applications of CPPs/therapeutic agents in the treatment of diabetes. Hypoglycemic drugs with CPPs intervention can enhance therapeutic effectiveness, and CPP-mediated drug delivery can facilitate the actions of insulin. Numerous studies indicate that CPPs can effectively deliver insulin, produce synergistic effects with immunosuppressants for successful pancreatic islet xenotransplantation, prolong pharmacokinetics, and retard diabetic nephropathy.

CONCLUSION

We suggest that CPPs can be a new generation of drug delivery systems for effective treatment and management of diabetes and diabetes-associated complications.

Intracellular Delivery by Membrane Disruption: Mechanisms, Strategies, and Concepts

Intracellular delivery is a key step in biological research and has enabled decades of biomedical discoveries. It is also becoming increasingly important in industrial and medical applications ranging from biomanufacture to cell-based therapies. Here, we review techniques for membrane disruption-based intracellular delivery from 1911 until the present. These methods achieve rapid, direct, and universal delivery of almost any cargo molecule or material that can be dispersed in solution. We start by covering the motivations for intracellular delivery and the challenges associated with the different cargo types-small molecules, proteins/peptides, nucleic acids, synthetic nanomaterials, and large cargo. The review then presents a broad comparison of delivery strategies followed by an analysis of membrane disruption mechanisms and the biology of the cell response. We cover mechanical, electrical, thermal, optical, and chemical strategies of membrane disruption with a particular emphasis on their applications and challenges to implementation. Throughout, we highlight specific mechanisms of membrane disruption and suggest areas in need of further experimentation. We hope the concepts discussed in our review inspire scientists and engineers with further ideas to improve intracellular delivery.

Cationic cell-penetrating peptides as vehicles for siRNA delivery

RNA interference mediated gene silencing has tremendous applicability in fields ranging from basic biological research to clinical therapy. However, delivery of siRNA across the cell membrane into the cytoplasm, where the RNA silencing machinery is located, is a significant hurdle in most primary cells. Cell-penetrating peptides (CPPs), peptides that possess an intrinsic ability to translocate across cell membranes, have been explored as a means to achieve cellular delivery of siRNA. Approaches using CPPs by themselves or through incorporation into other siRNA delivery platforms have been investigated with the intent of improving cytoplasmic delivery. Here, we review the utilization of CPPs for siRNA delivery with a focus on strategies developed to enhance cellular uptake, endosomal escape and cytoplasmic localization of CPP/siRNA complexes.

Inhibition of regulated cell death by cell-penetrating peptides

Development of the means to efficiently and continuously renew missing and non-functional proteins in diseased cells remains a major goal in modern molecular medicine. While gene therapy has the potential to achieve this, substantial obstacles must be overcome before clinical application can be considered. A promising alternative approach is the direct delivery of non-permeant active biomolecules, such as oligonucleotides, peptides and proteins, to the affected cells with the purpose of ameliorating an advanced disease process. In addition to receptor-mediated endocytosis, cell-penetrating peptides are widely used as vectors for rapid translocation of conjugated molecules across cell membranes into intracellular compartments and the delivery of these therapeutic molecules is generally referred to as novel prospective protein therapy. As a broad coverage of the enormous amount of published data in this field is unrewarding, this review will provide a brief, focused overview of the technology and a summary of recent studies of the most commonly used protein transduction domains and their potential as therapeutic agents for the treatment of cellular damage and the prevention of regulated cell death.

Nanoparticles and DNA - a powerful and growing functional combination in bionanotechnology

Functionally integrating DNA and other nucleic acids with nanoparticles in all their different physicochemical forms has produced a rich variety of composite nanomaterials which, in many cases, display unique or augmented properties due to the synergistic activity of both components. These capabilities, in turn, are attracting greater attention from various research communities in search of new nanoscale tools for diverse applications that include (bio)sensing, labeling, targeted imaging, cellular delivery, diagnostics, therapeutics, theranostics, bioelectronics, and biocomputing to name just a few amongst many others. Here, we review this vibrant and growing research area from the perspective of the materials themselves and their unique capabilities. Inorganic nanocrystals such as quantum dots or those made from gold or other (noble) metals along with metal oxides and carbon allotropes are desired as participants in these hybrid materials since they can provide distinctive optical, physical, magnetic, and electrochemical properties. Beyond this, synthetic polymer-based and proteinaceous or viral nanoparticulate materials are also useful in the same role since they can provide a predefined and biocompatible cargo-carrying and targeting capability. The DNA component typically provides sequence-based addressability for probes along with, more recently, unique architectural properties that directly originate from the burgeoning structural DNA field. Additionally, DNA aptamers can also provide specific recognition capabilities against many diverse non-nucleic acid targets across a range of size scales from ions to full protein and cells. In addition to appending DNA to inorganic or polymeric nanoparticles, purely DNA-based nanoparticles have recently surfaced as an excellent assembly platform and have started finding application in areas like sensing, imaging and immunotherapy. We focus on selected and representative nanoparticle-DNA materials and highlight their myriad applications using examples from the literature. Overall, it is clear that this unique functional combination of nanomaterials has far more to offer than what we have seen to date and as new capabilities for each of these materials are developed, so, too, will new applications emerge.

Precise quantification of cellular uptake of cell-penetrating peptides using fluorescence-activated cell sorting and fluorescence correlation spectroscopy

Cell-penetrating peptides (CPPs) have emerged as a potentially powerful tool for drug delivery due to their ability to efficiently transport a whole host of biologically active cargoes into cells. Although concerted efforts have shed some light on the cellular internalization pathways of CPPs, quantification of CPP uptake has proved problematic. Here we describe an experimental approach that combines two powerful biophysical techniques, fluorescence-activated cell sorting (FACS) and fluorescence correlation spectroscopy (FCS), to directly, accurately and precisely measure the cellular uptake of fluorescently-labeled molecules. This rapid and technically simple approach is highly versatile and can readily be applied to characterize all major CPP properties that normally require multiple assays, including amount taken up by cells (in moles/cell), uptake efficiency, internalization pathways, intracellular distribution, intracellular degradation and toxicity threshold. The FACS-FCS approach provides a means for quantifying any intracellular biochemical entity, whether expressed in the cell or introduced exogenously and transported across the plasma membrane.

Aptamer mediated niosomal drug delivery

Development of nanoscale carrier systems for targeted drug delivery is crucial for cancer treatment.

Delivery of nucleic acids and nanomaterials by cell-penetrating peptides: opportunities and challenges

Many viral and nonviral systems have been developed to aid delivery of biologically active molecules into cells. Among these, cell-penetrating peptides (CPPs) have received increasing attention in the past two decades for biomedical applications. In this review, we focus on opportunities and challenges associated with CPP delivery of nucleic acids and nanomaterials. We first describe the nature of versatile CPPs and their interactions with various types of cargoes. We then discuss in vivo and in vitro delivery of nucleic acids and nanomaterials by CPPs. Studies on the mechanisms of cellular entry and limitations in the methods used are detailed.

Study on nanocomposite construction based on the multi-functional biotemplate self-assembled by the recombinant TMGMV coat protein for potential biomedical applications

Nowadays there is a growing interest in bio-scaffolded nanoarchitectures. Rapid progress in nanobiotechnology and molecular biology has allowed the engineering of inorganic-binding peptides termed as genetically engineered polypeptides for inorganics (GEPIs) into self-assembling biological structures to facilitate the design of novel biomedical or bioimaging devices. Here we introduce a novel nanocomposite comprising a self-assembled protein scaffold based on a recombinant tobacco mild green mosaic tobamovirus (TMGMV) coat protein (CP) and the photocatalytic TiO2 nanoparticles attached to it, which may provide a generic method for materials engineering. A template containing a modified TMGMV CP (mCP) gene, with the first six C-terminal amino acid residues deleted to accommodate more foreign peptides and expressing a site-directed mutation of A123C for bioconjugation utility, and two genetically engineered mutants, Escherichia coli-based P-mCP-Ti7 containing a C-terminal TiO2 GEPI sequence of seven peptides (Ti7) and Hi5 insect cells-derived E-CP-Ti7-His6 C-terminally fused with Ti7+His6 tag were created. Expression vectors and protocols for enriching of the two CP variants were established and the resultant proteins were identified by western blot analysis. Their RNA-free self-assembling structures were analyzed by transmission electron microscopy (TEM) and immuno-gold labeling TEM analysis. Adherence of nanoparticles to the P-mCP-Ti7 induced protein scaffold was visualized by TEM analysis. Also discussed is the Cysteine thiol reactivity in bioconjugation reactions with the maleimide-functionalized porphyrin photosensitizers which can function as clinical photodynamic therapy agents. This study introduced a novel approach to producing an assembly-competent recombinant TMGMV CP, examined its ability to serve as a novel platform for the multivalent display of surface ligands and demonstrated an alternative method for nanodevice synthesis for nanobiotechnological applications by combining GEPIs-mediated immobilization with the controllability of self-assembling recombinant TMGMV CP.

Delivery of nucleic acids, proteins, and nanoparticles by arginine-rich cell-penetrating peptides in rotifers

Cell-penetrating peptides (CPPs) are a group of short, membrane-permeable cationic peptides that represent a nonviral technology for delivering nanomaterials and macromolecules into live cells. In this study, two arginine-rich CPPs, HR9 and IR9, were found to be capable of entering rotifers. CPPs were able to efficiently deliver noncovalently associated with cargoes, including plasmid DNAs, red fluorescent proteins (RFPs), and semiconductor quantum dots, into rotifers. The functional reporter gene assay demonstrated that HR9-delivered plasmid DNAs containing the enhanced green fluorescent protein and RFP coding sequences could be actively expressed in rotifers. The 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan assay further confirmed that CPP-mediated cargo delivery was not toxic to rotifers. Thus, these two CPPs hold a great potential for the delivery of exogenous genes, proteins, and nanoparticles in rotifers.

Peptide-lipid interactions: experiments and applications

The interactions between peptides and lipids are of fundamental importance in the functioning of numerous membrane-mediated cellular processes including antimicrobial peptide action, hormone-receptor interactions, drug bioavailability across the blood-brain barrier and viral fusion processes. Moreover, a major goal of modern biotechnology is obtaining new potent pharmaceutical agents whose biological action is dependent on the binding of peptides to lipid-bilayers. Several issues need to be addressed such as secondary structure, orientation, oligomerization and localization inside the membrane. At the same time, the structural effects which the peptides cause on the lipid bilayer are important for the interactions and need to be elucidated. The structural characterization of membrane active peptides in membranes is a harsh experimental challenge. It is in fact accepted that no single experimental technique can give a complete structural picture of the interaction, but rather a combination of different techniques is necessary.

Endocytic Trafficking of Nanoparticles Delivered by Cell-penetrating Peptides Comprised of Nona-arginine and a Penetration Accelerating Sequence

Cell-penetrating peptides (CPPs) can traverse cellular membranes and deliver biologically active molecules into cells. In this study, we demonstrate that CPPs comprised of nona-arginine (R9) and a penetration accelerating peptide sequence (Pas) that facilitates escape from endocytic lysosomes, denoted as PR9, greatly enhance the delivery of noncovalently associated quantum dots (QDs) into human A549 cells. Mechanistic studies, intracellular trafficking analysis and a functional gene assay reveal that endocytosis is the main route for intracellular delivery of PR9/QD complexes. Endocytic trafficking of PR9/QD complexes was monitored using both confocal and transmission electron microscopy (TEM). Zeta-potential and size analyses indicate the importance of electrostatic forces in the interaction of PR9/QD complexes with plasma membranes. Circular dichroism (CD) spectroscopy reveals that the secondary structural elements of PR9 have similar conformations in aqueous buffer at pH 7 and 5. This study of nontoxic PR9 provides a basis for the design of optimized cargo delivery that allows escape from endocytic vesicles.

Intracellular delivery of nanoparticles and DNAs by IR9 cell-penetrating peptides

Cell-penetrating peptides (CPPs) comprised of basic amino residues are able to cross cytoplasmic membranes and are able to deliver biologically active molecules inside cells. However, CPP/cargo entrapment in endosome limits biomedical utility as cargoes are destroyed in the acidic environment. In this study, we demonstrate protein transduction of a novel CPP comprised of an INF7 fusion peptide and nona-arginine (designated IR9). IR9 noncovalently interacts with quantum dots (QDs) and DNAs to form stable IR9/QD and IR9/DNA complexes which are capable of entering human A549 cells. Zeta-potentials were a better predictor of transduction efficiency than gel shift analysis, emphasizing the importance of electrostatic interactions of CPP/cargo complexes with plasma membranes. Mechanistic studies revealed that IR9, IR9/QD and IR9/DNA complexes may enter cells by endocytosis. Further, IR9, IR9/QD and IR9/DNA complexes were not cytotoxic at concentrations below 30, 5 and 20.1 µM, respectively. Without labor intensive production of fusion proteins from prokaryotes, these results indicate that IR9 could be a safe carrier of genes and drugs in biomedical applications.

Mechanistic studies of intracellular delivery of proteins by cell-penetrating peptides in cyanobacteria

Background

The plasma membrane plays an essential role in selective permeability, compartmentalization, osmotic balance, and cellular uptake. The characteristics and functions of cyanobacterial membranes have been extensively investigated in recent years. Cell-penetrating peptides (CPPs) are special nanocarriers that can overcome the plasma membrane barrier and enter cells directly, either alone or with associated cargoes. However, the cellular entry mechanisms of CPPs in cyanobacteria have not been studied.

Results

In the present study, we determine CPP-mediated transduction efficiency and internalization mechanisms in cyanobacteria using a combination of biological and biophysical methods. We demonstrate that both Synechocystis sp. PCC 6803 and Synechococcus elongatus PCC 7942 strains of cyanobacteria possess red autofluorescence. Green fluorescent protein (GFP), either alone or noncovalently associated with a CPP comprised of nine arginine residues (R9/GFP complexes), entered cyanobacteria. The ATP-depleting inhibitor of classical endocytosis, N-ethylmaleimide (NEM), could block the spontaneous internalization of GFP, but not the transduction of R9/GFP complexes. Three specific inhibitors of macropinocytosis, cytochalasin D (CytD), 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), and wortmannin, reduced the efficiency of R9/GFP complex transduction, indicating that entry of R9/GFP complexes involves macropinocytosis. Both the 1-(4,5-dimethylthiazol-2-yl)-3,5-diphenylformazan (MTT) and membrane leakage analyses confirmed that R9/GFP complexes were not toxic to the cyanobacteria, nor were the endocytic and macropinocytic inhibitors used in these studies.

Conclusions

In summary, we have demonstrated that cyanobacteria use classical endocytosis and macropinocytosis to internalize exogenous GFP and CPP/GFP proteins, respectively. Moreover, the CPP-mediated delivery system is not toxic to cyanobacteria, and can be used to investigate biological processes at the cellular level in this species. These results suggest that both endocytic and macropinocytic pathways can be used for efficient internalization of regular protein and CPP-mediated protein delivery in cyanobacteria, respectively.

Protein transduction in human cells is enhanced by cell-penetrating peptides fused with an endosomolytic HA2 sequence

Endocytosis has been proposed as one of the primary mechanisms for cellular entry of cell-penetrating peptides (CPPs) and their cargoes. However, a major limitation of endocytic pathway is entrapment of the CPP-cargo in intracellular vesicles from which the cargo must escape into the cytoplasm to exert its biological activity. Here we demonstrate that a CPP tagged with an endosomolytic fusion peptide derived from the influenza virus hemagglutinin-2 (HA2) remarkably enhances the cytosolic delivery of proteins in human A549 cells. To determine the endosome-disruptive effects, recombinant DNA plasmids containing coding sequences of HA2, CPPs and red fluorescent proteins (RFPs) were constructed. The fusion proteins were purified from plasmid-transformed Escherichia coli, and their effects on protein transduction were examined using live cell imaging and flow cytometry. Our data indicate that endocytosis is the major route for cellular internalization of CPP-HA2-tagged RFP. Mechanistic studies revealed that the fusogenic HA2 peptide dramatically facilitates CPP-mediated protein entry through the release of endocytosed RFPs from endosomes into the cytoplasm. Furthermore, incorporating the HA2 fusion peptide of the CPP-HA2 fusion protein improved cytosolic uptake without causing cytotoxicity. These findings strongly suggest that the CPP-HA2 tag could be an efficient and safe carrier that overcomes endosomal entrapment of delivered therapeutic drugs.

Polymer coated inorganic nanoparticles: tailoring the nanocrystal surface for designing nanoprobes with biological implications

The use of inorganic nanoparticles in biomedicine, in particular in the field of diagnosis and therapy of human diseases, has rapidly grown in the last few decades. Water solubilisation of the nanoparticles, especially for particles synthesized in non-polar solvents, is an essential prerequisite for their biological exploitation. The encapsulation of surfactant coated nanoparticles into polymer shells represents one of the most suitable and most popular methods to make them water soluble. Herein we provide an overview of the amphiphilic polymer molecules used and the efforts undertaken to further tailor the surface of polymer coated nanoparticles with fluorescent dyes, chemical sensor molecules and small or large biomolecules for the preparation of bio-functional nanoprobes. Their biological implications, highlighting limitations and challenges, are also discussed.

Arginine-rich cell-penetrating peptides deliver gene into living human cells

Transgenesis is a process that introduces exogenous nucleic acids into the genome of an organism to produce desired traits or evaluate function. Improvements of transgenic technologies are always important pursuit in the last decades. Recently, cell-penetrating peptides (CPPs) were studied as shuttles that can internalize into cells directly and serve as carriers to deliver different cargoes into cells. In the present study, we evaluate whether arginine-rich CPPs can be used for gene delivery into human cells in a noncovalent fashion. We demonstrate that three arginine-rich CPPs (SR9, HR9, and PR9) are able to transport plasmid DNA into human A549 cells. For the functional gene assay, the CPP-delivered plasmid DNA containing the enhanced green fluorescent protein (EGFP) coding sequence could be actively expressed in cells. The treatment of calcium chloride did not facilitate the CPP-mediated transfection efficiency, but enhance the gene expression intensity. Mechanistic studies further revealed that HR9/DNA complexes mediate the direct membrane translocation pathway for gene delivery. Our results suggest that arginine-rich CPPs, especially HR9, appear to be a high efficient and promising tool for gene transfer.

In vitro and in vivo studies on gelatin-siloxane nanoparticles conjugated with SynB peptide to increase drug delivery to the brain

BACKGROUND

Nanobiotechnology can provide more efficient tools for diagnosis, targeted and personalized therapy, and increase the chances of brain tumor treatment being successful. Use of nanoparticles is a promising strategy for overcoming the blood-brain barrier and delivering drugs to the brain. Gelatin-siloxane (GS) nanoparticles modified with Tat peptide can enhance plasmid DNA transfection efficiency compared with a commercial reagent.

METHODS

SynB-PEG-GS nanoparticles are membrane-penetrable, and can cross the blood-brain barrier and deliver a drug to its target site in the brain. The efficiency of delivery was investigated in vivo and in vitro using brain capillary endothelial cells, a cocultured blood-brain barrier model, and a normal mouse model.

RESULTS

Our study demonstrated that both SynB-PEG-GS and PEG-GS nanoparticles had a spherical shape and an average diameter of 150-200 nm. It was shown by MTT assay that SynB-PEG-GS nanoparticles had good biocompatibility with brain capillary endothelial cells. Cellular uptake by SynB-PEG-GS nanoparticles was higher than that for PEG-GS nanoparticles for all incubation periods. The amount of SynB-PEG-GS nanoparticles crossing the cocultured blood-brain barrier model was significantly higher than that of PEG-GS nanoparticles at all time points measured (P < 0.05). In animal testing, SynB-PEG-GS nanoparticle levels in the brain were significantly higher than those of PEG-GS nanoparticles at all time points measured (P < 0.01). In contrast with localization in the brain, PEG-GS nanoparticle levels were significantly higher than those of SynB-PEG-GS nanoparticles (P < 0.01) in the liver.

CONCLUSION

This study indicates that SynB-PEG-GS nanoparticles have favorable properties with regard to morphology, size distribution, and toxicity. Moreover, the SynB-PEG-GS nanoparticles exhibited more efficient brain capillary endothelial cell uptake and improved crossing of the blood-brain barrier. Further, biodistribution studies of rhodamine-loaded nanoparticles demonstrated that modification with the SynB peptide could not only improve the ability of PEG-GS nanoparticles to evade capture in the reticuloendothelial system but also enhance their efficiency in crossing the blood-brain barrier.

Sendai virus-based liposomes enable targeted cytosolic delivery of nanoparticles in brain tumor-derived cells

Background

Nanotechnology-based bioassays that detect the presence and/or absence of a combination of cell markers are increasingly used to identify stem or progenitor cells, assess cell heterogeneity, and evaluate tumor malignancy and/or chemoresistance. Delivery methods that enable nanoparticles to rapidly detect emerging, intracellular markers within cell clusters of biopsies will greatly aid in tumor characterization, analysis of functional state and development of treatment regimens.

Results

Experiments utilized the Sendai virus to achieve in vitro, cytosolic delivery of Quantum dots in cells cultured from Human brain tumors. Using fluorescence microscopy and Transmission Electron Microscopy, in vitro experiments illustrated that these virus-based liposomes decreased the amount of non-specifically endocytosed nanoparticles by 50% in the Human glioblastoma and medulloblastoma samples studied. Significantly, virus-based liposome delivery also facilitated targeted binding of Quantum dots to cytosolic Epidermal Growth Factor Receptor within cultured cells, focal to the early detection and characterization of malignant brain tumors.

Conclusions

These findings are the first to utilize the Sendai virus to achieve cytosolic, targeted intracellular binding of Qdots within Human brain tumor cells. The results are significant to the continued applicability of nanoparticles used for the molecular labeling of cancer cells to determine tumor heterogeneity, grade, and chemotherapeutic resistivity.

A gene delivery system for insect cells mediated by arginine-rich cell-penetrating peptides

Most bioactive macromolecules, such as protein, DNA and RNA, basically cannot permeate into cells freely from outside the plasma membrane. Cell-penetrating peptides (CPPs) are a group of short peptides that possess the ability to traverse the cell membrane and have been considered as candidates for mediating gene and drug delivery into living cells. In this study, we demonstrate that three arginine-rich CPPs (SR9, HR9 and PR9) are able to form stable complexes with plasmid DNA and deliver DNA into insect Sf9 cells in a noncovalent manner. The transferred plasmid DNA containing enhanced green fluorescent protein (EGFP) and red fluorescent protein (RFP) coding regions could be expressed in cells functionally assayed at both the protein and RNA levels. Furthermore, treatment of cells with CPPs and CPP/DNA complexes resulted in a viability of 84-93% indicating these CPPs are not cytotoxic. These results suggest that arginine-rich CPPs appear to be a promising tool for insect transgenesis.

Beauty is skin deep: a surface monolayer perspective on nanoparticle interactions with cells and bio-macromolecules

Surface recognition of biosystems is a critical component in the development of novel biosensors and delivery vehicles, and for the therapeutic regulation of biological processes. Monolayer-protected nanoparticles present a highly versatile scaffold for selective interaction with bio-macromolecules and cells. Through the engineering of the monolayer surface, nanoparticles can be tailored for surface recognition of biomolecules and cells. This review highlights recent progress in nanoparticle-bio-macromolecule/cellular interactions, emphasizing the effect of the surface monolayer structure on the interactions with proteins, DNA, and cell surfaces. The extension of these tailored interactions to hybrid nanomaterials, biosensing platforms, and delivery vehicles is also discussed.

A gene delivery system for human cells mediated by both a cell-penetrating peptide and a piggyBac transposase

The piggyBac (PB) transposable element has recently accumulated enormous attention as a tool for the transgenesis in various eukaryotic organisms. Arginine-rich cell-penetrating peptides (CPPs) are protein transduction domains containing a large amount of basic amino acids that were found to be capable of delivering biologically active macromolecules into living cells. In this study, we demonstrate a strategy, which we called "transposoduction", which is a one-plasmid gene delivery system mediated by the nontoxic CPP-piggyBac transposase (CPP-PBase) fusion protein to accomplish both protein transduction and transposition. CPPs were proven to be able to synchronously deliver covalently linked PBase and noncovalently linked a cis plasmid into human cells. The expression of promoterless reporter genes coding for red (dTomato) and yellow (mOrange) fluorescent proteins (RFP and YFP) with PB elements could be detected in cells treated with the PBase-expressing plasmid after 3 days indicating transposition of coding regions to downstream of endogenous promoter sequences. An enhanced green fluorescent protein (EGFP) plasmid-based excision assay further confirmed the efficiency of the bifunctional CPP-PBase fusion protein. In conclusion, this strategy representing a combinational concept of both protein transduction and mobile transposition may provide tremendous potential for safe and efficient cell line transformation, gene therapy and functional genomics.

Intracellular delivery of quantum dots mediated by a histidine- and arginine-rich HR9 cell-penetrating peptide through the direct membrane translocation mechanism

Functional peptides that transfer biomaterials, such as semiconductor quantum dots (QDs), into cells in biomaterial research have been developed in recent years. Delivery of QDs conjugated with cell-penetrating peptides (CPPs) into cells by the endocytic pathway was problematic in biomedical applications because of lysosomal trapping. Here, we demonstrate that histidine- and arginine-rich CPPs (HR9 peptides) stably and noncovalently combined with QDs are able to enter into cells in an extremely short period (4 min). Interrupting both F-actin polymerization and active transport did not inhibit the entry of HR9/QD complexes into cells, indicating that HR9 penetrates cell membrane directly. Subcellular colocalization studies indicated that QDs delivered by HR9 stay in cytosol without any organelle capture. Dimethyl sulphoxide, ethanol and oleic acid, but not pyrenebutyrate, enhanced HR9-mediated intracellular delivery of QDs by promoting the direct membrane translocation pathway. HR9 and HR9/QDs were not cytotoxic. These findings suggest that HR9 could be an efficient carrier to deliver drugs without interfering with their therapeutic activity.