Cellular Uptake Capability Research Articles

Effect of Degree of Substitution and Molecular Weight on Transfection Efficacy of Starch-Based siRNA Delivery System

RNA interference (RNAi) is a promising approach for gene therapy in cancers, but it requires carriers to protect and deliver therapeutic small interfering RNA (siRNA) molecules to cancerous cells. Starch-based carriers, such as quaternized starch (Q-Starch), have been shown to be biocompatible and are able to form nanocomplexes with siRNA, but significant electrostatic interactions between the carrier and siRNA prevent its release at the target site. In this study, we aim to characterize the effects of the degree of substitution (DS) and molecular weight (Mw) of Q-Starch on the gene silencing capabilities of the Q-Starch/siRNA transfection system. We show that reducing the DS reduces the electrostatic interactions between Q-Starch and siRNA, which now decomplex at more physiologically relevant conditions, but also affects additional parameters such as complex size while mostly maintaining cellular uptake capabilities. Notably, reducing the DS renders Q-Starch more susceptible to enzymatic degradation by α-amylase during the initial Q-Starch pretreatment. Enzymatic cleavage leads to a reduction in the Mw of Q-Starch, resulting in a 25% enhancement in its transfection capabilities. This study provides a better understanding of the effects of the DS and Mw on the polysaccharide-based siRNA delivery system and indicates that the polysaccharide Mw may be the key factor in determining the transfection efficacy of this system.

Tumor microenvironment activated mussel-inspired hollow mesoporous nanotheranostic for enhanced synergistic photodynamic/chemodynamic therapy

Anti-tumor therapies reliant on reactive oxygen species (ROS) as primary therapeutic agents face challenges due to a limited oxygen substrate. Photodynamic therapy (PDT) is particularly hindered by inherent hypoxia, while chemodynamic therapy (CDT) encounters obstacles from insufficient endogenous hydrogen peroxide (H2O2) levels. In this study, we engineered biodegradable tumor microenvironment (TME)-activated hollow mesoporous MnO2-based nanotheranostic agents, designated as HAMnO2A. This construct entails loading artemisinin (ART) into the cavity and surface modification with a mussel-inspired polymer ligand, namely hyaluronic acid-linked poly(ethylene glycol)-diethylenetriamine-conjugated (3,4-dihydroxyphenyl) acetic acid, and the photosensitizer Chlorin e6 (mPEG-HA-Dien-(Dhpa/Ce6)), facilitating dual-modal imaging-guided PDT/CDT synergistic therapy. In vitro experimentation revealed that HAMnO2A exhibited ideal physiological stability and enhanced cellular uptake capability via CD44-mediated endocytosis. Additionally, it was demonstrated that accelerated endo-lysosomal escape through the pH-dependent protonation of Dien. Within the acidic and highly glutathione (GSH)-rich TME, the active component of HAMnO2A, MnO2, underwent decomposition, liberating oxygen and releasing both Mn2+ and ART. This process alleviates hypoxia within the tumor region and initiates a Fenton-like reaction through the combination of ART and Mn2+, thereby enhancing the effectiveness of PDT and CDT by generating increased singlet oxygen (1O2) and hydroxyl radicals (•OH). Moreover, the presence of Mn2+ ions enabled the activation of T1-weighted magnetic resonance imaging. In vivo findings further validated that HAMnO2A displayed meaningful tumor-targeting capabilities, prolonged circulation time in the bloodstream, and outstanding efficacy in restraining tumor growth while inducing minimal damage to normal tissues. Hence, this nanoplatform serves as an efficient all-in-one solution by facilitating the integration of multiple functions, ultimately enhancing the effectiveness of tumor theranostics.

Carboxymethyl Tamarind seed polysaccharide nanoparticles as a potent mucomimetic and biocompatible oral nanocarrier

A novel mucomimetic and biocompatible nanocarrier, carboxymethyl tamarind seed polysaccharide (CMTSP) nanoparticles, were synthesized using ionic gelation. The nanoparticles were spherical, with a narrow size distribution (175 ± 10.3 nm), as demonstrated by electron microscopy. Furthermore, the nanoparticles were physicochemically characterized by Fourier-transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and X-ray powder diffraction (XRD) analysis, which illustrated the free state of the encapsulated drug (Amphotericin B) and amorphous nature of the nanoformulation. The well-optimized nanoparticles showed an encapsulation efficiency of 83.98 ± 0.92% and a drug loading of 15.63 ± 3.61%. In-vitro drug release experiments showed the biphasic pattern of drug release from CMTSP nanoparticles, with an initial burst release of 10% and a sustained release up to the next 48 hours. The CMTSP modification conferred the orally administered nanoparticles with hydrophilicity (50% reduction in contact angle) and exceptional antioxidant ability (57.4% free radical scavenging activity). The nanoparticles exhibited pH-dependent swelling behavior and were stable in simulated gastrointestinal fluids. Moreover, the nanoparticles exhibited superior cell viability and excellent cellular uptake capability. With these unique properties of the natural water-soluble polysaccharide of tamarind, CMTSP provides nanoparticles with hydrophilicity, biocompatibility, mucus-mimicking behavior, and stability.

In-depth study of anticancer drug diffusion through a cross-linked ­pH-responsive polymeric vesicle membrane

Post-encapsulation and release of the anticancer drug doxorubicin hydrochloride (DOX·HCl) through cell-like transmission functions of polymeric vesicles were studied using cross-linked pH-responsive polymeric vesicles. The vesicles were fabricated for the first time via the redox-initiated reversible addition-fragmentation chain transfer dispersion polymerization in ethanol-water mixture, using 2-(diisopropylamino)ethyl methacrylate and glycidyl methacrylate, and the vesicle membrane was modified post-cross-linking by using ethylenediamine. A phase diagram was constructed for reproducible fabrication of the polymeric vesicles, and well-shaped vesicles were formed when the target degree of polymerization of the hydrophobic polymer chains was equal to or higher than 50 with solid content in the range of 10–30 wt%. The cross-linked vesicle membrane served as a gate enabling “open” and “closed” states in response to pH stimulation. Up to 50% drug loading efficiency and 39% drug loading content could be achieved, and in vitro release of the DOX-loaded vesicles in aqueous buffer solutions showed a much faster DOX release rate at pH 5.0 than at pH 6.5. The polymeric vesicles were of very low cytotoxicity to A549 cells up to the concentration of 2 mg/mL, and the IC50 of DOX-loaded vesicles were higher than that of the free DOX. The intracellular DOX release study indicated higher cellular uptake capability for DOX-loaded vesicles than that of free DOX.

Photoreactive Cytosine-Functionalized Self-Assembled Micelles with Enhanced Cellular Uptake Capability for Efficient Cancer Chemotherapy.

Design, fabrication, and control of photoreactive supramolecular macromers─which are composed of a thermoresponsive polymer backbone and photoreactive nucleobase end-groups─to achieve the desired physical-chemical performance and provide the high efficiency required for chemotherapy drug delivery purposes still present challenges. Herein, a difunctional cytosine-terminated supramolecular macromer was successfully obtained at high yield. UV-irradiation induces the formation of cytosine photodimers within the structure. The irradiated macromer can self-assemble into nanosized spherical micelles in water that possess a number of interesting and unique features, such as desired micellar size and morphology, tunable drug-loading capacity, and excellent structural stability in serum-containing medium, in addition to well-controlled drug-release behaviors in response to changes in environmental temperature and pH; these extremely desirable, rare features are required to augment the functions of polymeric nanocarriers for drug delivery. Importantly, a series of in vitro studies demonstrated that photodimerized cytosine moieties within the drug-loaded micelles substantially enhance their internalization and accumulation inside cells via endocytosis and subsequently lead to induction of massive apoptotic cell death compared with the corresponding nonirradiated micelles. Thus, this newly developed "photomodified" nanocarrier system could provide a potentially fruitful route to enhance the drug delivery performance of nanocages without the need to introduce targeting moieties or additional components.

Self-Delivery Nanomedicine for Glutamine-Starvation Enhanced Photodynamic Tumor Therapy.

Glutamine metabolism of tumor cells plays a crucial role in maintaining cell homeostasis and reducing oxidative damage. Herein, a valid strategy of inhibiting glutamine metabolism is proposed to amplify the oxidative damage of photodynamic therapy (PDT) to tumor cells. Specifically, the authors develop a drug co-delivery system (designated as CeV) based on chlorine e6 (Ce6) and V9302 via the self-assembly technology. In spite of the strong hydrophobicity of therapeutic agents, the assembled CeV holds a favorable dispersibility in water and an improved cellular uptake capability. Under light irradiation, the internalized CeV is capable of generating abundant reactive oxygen species (ROS) for PDT. More importantly, CeV can reduce the uptake of glutamine through V9302-mediated alanine-serine-cysteine transporter of type-2 (ASCT2) inhibition, leading to a reduced glutathione (GSH) production and an amplified oxidative stress. As a result, CeV has a robust PDT efficacy on tumor inhibition by the blockade of glutamine transport. Notably, CeV exhibits a superiority on tumor suppression over the single treatment as well as the combined administration of Ce6 and V9302, which indicates the advantage of CeV for synergistic treatment. It may serve as a novel nanoplatform for developing a drug co-delivery system to improve PDT efficiency by inhibiting cell metabolism.

Aggregation-Induced Emission-Active Poly(phenyleneethynylene)s for Fluorescence and Raman Dual-Modal Imaging and Drug-Resistant Bacteria Killing.

Poly(phenyleneethynylene) (PPE) is a widely used functional conjugated polymer with applications ranging from organic optoelectronics and fluorescence sensors to optical imaging and theranostics. However, the fluorescence efficiency of PPE in aggregate states is generally not as good as their solution states, which greatly compromises their performance in fluorescence-related applications. Herein, a series of PPE derivatives with typical aggregation-induced emission (AIE) properties is designed and synthesized. In these PPEs, the diethylamino-substituted tetraphenylethene units function as the long-wavelength AIE source and the alkyl side chains serve as the functionalization site. The obtained AIE-active PPEs with large π-conjugation show strong aggregate-state fluorescence, interesting self-assembly behaviors, inherently enhanced alkyne vibrations in the Raman-silent region of cells, and efficient antibacterial activities. The PPE nanoparticles with good cellular uptake capability can clearly and sensitively visualize the tumor region and residual tumors via their fluorescence and Raman signals, respectively, to benefit the precise tumor resection surgery. After post-functionalization, the obtained PPE-based polyelectrolyte can preferentially image bacteria over mammalian cells and possesses efficient photodynamic killing capability against Gram-positive and drug-resistant bacteria. This work provides a feasible design strategy for developing functional conjugated polymers with multimodal imaging capability as well as photodynamic antimicrobial ability.

Acylation of antimicrobial peptide-plasmid DNA vectors formulation for efficient gene delivery in cancer therapy

Antimicrobial peptides/DNA complexes were designed based on AMPs chensinin-1b and its corresponding lipo-chensinin-1b conjugated with an aliphatic acid with different chain lengths and therapeutic genes. The main goal of such a complex includes two aspects: first, antimicrobial peptides deliver therapeutic genes to cancer cells and genes expressed in targeted tissue for cancer gene therapy, and, second, the antimicrobial peptide kills cancer cells when used alone as an anticancer agent. This study presents a model composed of chensinin-1b and its lipo-chensinin-1b and eGFP plasmids, which were used as reporter genes, and the final peptide/eGFP plasmid complexes were analyzed by TEM and DLS. The gene transfection efficiency of the complex was evaluated by a microplate reader, FACS and CLSM. Compared with Lipo2000, the antimicrobial peptide showed specific selectivity for transfection against cancer cells and mammalian cells. The peptides chensinin-1b and lipo-chensinin-1b binding with the eGFP plasmid displayed optimal transfection efficiencies at a mass ratio of 8. In addition, PA-C1b can deliver p53-eGFP plasmids into MCF-7 cancer cells, and the proliferation of cells was inhibited and even caused cell death. Overall, PA-C1b was screened and found to have the highest transfection efficiency for gene delivery and good cellular uptake capability. The in vivo transfection ability of PA-C1b was investigated using a tumor-bearing mouse model, and the transfection efficiency reflected by the fluorescence of expressed GFP was determined by in vivo imaging. Conclusively, the antimicrobial peptide PA-C1b could be used as the nonviral vector with high efficiency for cancer gene therapy.

Tumor acid microenvironment-activated self-targeting & splitting gold nanoassembly for tumor chemo-radiotherapy

Low accumulation and penetration of nanomedicines in tumor severely reduce therapeutic efficacy. Herein, a pH-responsive gold nanoassembly is designed to overcome these problems. Polyethylene glycol linked raltitrexed (RTX, target ligand and chemotherapy drug) and two tertiary amine molecules (1-(2-aminoethyl) pyrrolidine and N,N-dibutylethylenediamine) are modified on the surface of the 6-nm gold nanoparticles by lipoic acid to form gold nanoassembly defined as Au-NNP(RTX). The Au-NNP (RTX) nanoassembly could remain at about 160 nm at the blood circulation (pH 7.4), while split into 6-nm gold nanoparticles due to tertiary amine protonation at tumor extracellular pH (pH 6.8). This pH-responsive disassembly behavior endows Au-NNP(RTX) better tumor tissue permeability through the better diffusion brought by the size reduction. Meanwhile, after disassembly, more RTXs on the surface of gold nanoparticles are exposed from the shielded state of assembly along with 2.25-fold augment of cellular uptake capability. Most importantly, the results show that Au-NNP(RTX) possesses of high tumor accumulation and effective tumor penetration, thereby enhancing the tumor chemo-radiotherapy efficiency.

Multi-stimuli responsive hollow MnO2-based drug delivery system for magnetic resonance imaging and combined chemo-chemodynamic cancer therapy

The exploration and application of hollow manganese dioxide nanoparticle (HMDN) for biosensing and biomedicine has gained significant research attention in the past decade. In this study, a type of biodegradable HMDN is prepared for multi-stimuli responsive tumor-targeted drug delivery, which was successfully loaded with doxorubicin hydrochloride (DOX). Then, the drug-loaded HMDN is functionalized with polyethyleneimine (PEI) as a gatekeeper followed by citraconic anhydride (cit) functionalized poly-L-lysine (PLL(cit)) as a charge reversal moiety successively to yield the resultant DOX@HMDN-PEI-PLL(cit) nanoparticles. In vitro study showed that DOX@HMDN-PEI-PLL(cit) exhibited a ‘‘stealthy’’ property under physiological conditions and enhanced cellular uptake activity in response to the mild acidic tumor microenvironment due to the departure of cit. In vitro release profiles proved that the decomposition of HMDN to Mn2+ under acidic condition/high glutathione (GSH) concentration triggered the release of DOX and Fenton-like reaction for improved therapeutic effect. And Mn2+ could also act as a T1-weighted magnetic resonance imaging (MRI) contrast agent. In vivo studies further proved with both the charge reversal and combined therapy properties, DOX@HMDN-PEI-PLL(cit) showed a good tumor enrichment ability and therapeutic effect with few side effects to the mice. These results demonstrate that DOX@HMDN-PEI-PLL(cit) nanoparticles are promising drug delivery systems for targeted cancer therapy. Statement of significanceTraditional chemotherapy based on anticancer drugs such as doxorubicin hydrochloride (DOX) shows limited efficacy with serious side effects. We employed hollow manganese dioxide nanoparticle (HMDN) to loaded DOX and coated it with polyethyleneimine and then citraconic anhydride functionalized poly-L-lysine to endow it with a charge reversal property to obtain a multi-stimuli responsive drug delivery system named DOX@HMDN-PEI-PLL(cit). It was ‘‘stealthy’’ with low cellular uptake capability by normal cells, but could be “acid-activated” in tumors for endocytosis by cancer cells to reduce side effects. HMDN could be decomposed to Mn2+ under acidic conditions/high glutathione concentration to release DOX intracellular. DOX and Mn2+ catalyzed Fenton-like reaction could achieve a combined chemo-chemodynamic therapy. And Mn2+ could be used for T1-weighted magnetic resonance imaging.

Rambutan-like silica nanoparticles at tailored particle sizes for plasmid DNA delivery

Silica nanoparticles (SNPs) have attracted widespread attention as biocompatible and efficient nanocarriers for gene delivery. The physicochemical properties of SNPs such as particle size, pore size, nanotopography and surface chemistry play important roles in regulating the intracellular delivery performance of genetic molecules. SNPs engineered with a rambutan-like spiky surface (Ram-SNPs) have shown significantly enhanced transfection efficiency for plasmid DNA (pDNA). However, the impact of the particle size of Ram-SNPs on their pDNA delivery performance has not been reported. Here, we synthesized Ram-SNPs with tailored nanoparticles sizes of 180, 330 and 520 nm by controlling the polymerization of resorcinol–formaldehyde and silica in a surfactant-free synthesis system. The polyethylenimine modified Ram-SNPs were loaded with pDNA molecules for intracellular delivery. Smaller sized Ram-SNPs demonstrated slightly weaker binding with pDNA, enhanced cellular uptake and significantly higher transfection efficiency than the larger particles. This structure–function relationship is different from other SNPs used for pDNA delivery. The cellular uptake mechanism by Ram-SNPs was also investigated. These findings provide useful guidance for the rational design of silica-based non-viral vectors for efficient gene delivery applications. A series of bioinspired rambutan-like silica nanoparticles with varied particle sizes were developed for plasmid DNA delivery, where smaller sized nanoparticles promoted the gene transfection efficiency due to enhanced cellular uptake capability.

Preparation and In Vitro Cellular Uptake Assessment of Multifunctional Rubik-Like Magnetic Nano-Assemblies.

Through self-assembly of nanoparticles into high-order and stable structures of cubic clusters, high drug-loading rubik-like magnetic nano-assemblies (MNAs), possessing folic acid targeting and strong magnetism-enhanced cellular uptake capabilities, were built. In this study, the core of the cubic drug assemblies consisted of four monodisperse superparamagnetic iron oxide nanoparticles coated with layers of oleic acid (Fe₃O₄@OA), simultaneously encapsulating fluorescein, and Paclitaxol (Flu-MNAs and PTX-MNAs) for imaging and therapeutic applications. To enable preferential tumor cellular uptake by the nanocarriers, the outermost layer of Fe₃O₄ was functionalized with the new dual-oleic acid-polyethylene glycol-folic acid polymer (FA-PEG-Lys-OA₂) as a "shell." The drug carriers exhibited excellent stability and biocompatibility, and showed high drug loading and excellent magnetic response In Vitro. Furthermore, preliminary evaluations of the drug carriers with Hela cells showed effective cellular targeting capability. In addition, the cubic assemblies enhanced anticancer efficiency for Hela cells compared to bare drugs. Especially, the applied external magnetic field further improved the uptake of the vectors, and thereby enhanced the inhibitory effect. In brief, all these results suggested that cubic assemblies could serve as potential strategies for targeted anticancer therapies.

Time-lapse live cell imaging to monitor doxorubicin release from DNA origami nanostructures.

Self-assembled DNA nanostructures have attracted significant research interest in biomedical applications because of their excellent programmability and biocompatibility. To develop multifunctional drug delivery from DNA nanostructures, considerable key information is still needed for clinical application. Traditional fixed endpoint assays do not reflect the dynamic and heterogeneous responses of cells with regard to drugs, and may lead to the misinterpretation of experimental results. For the first time, an integrated time-lapse live cell imaging system was used to study the cellular internalization and controlled drug release profile of three different shaped DNA origami/doxorubicin (DOX) complexes for three days. Our results demonstrated the dependence of DNA nanostructures on shape for drug delivery efficiency, while the rigid 3D DNA origami triangle frame exhibited enhanced cellular uptake capability, as compared with flexible 2D DNA structures. In addition, the translocation of released DOX into the nucleus was proved by fluorescence microscopy, in which a DOX-loaded 3D DNA triangle frame displayed a stronger accumulation of DOX in nuclei. Moreover, given the facile drug loading and auto fluorescence of the anti-cancer drug, DOX, our results suggest that the DNA nanostructure is a promising candidate, as a label-free nanocarrier, for DOX delivery, with great potential for anticancer therapy as well.

Liposome-modified titanium surface: A strategy to locally deliver bioactive molecules

Titanium and its alloys are widely employed materials for implants in orthopedic or dental surgery due to their mechanical properties, resistance to corrosion and osseointegration capability. However adverse reactions at the tissue/implant interface may occur, which limit the success of the osseointegration process. Therefore, different strategies have to be used to overcome these drawbacks. In this work, we developed two different liposome-based coatings on titanium surfaces as drug or bioactive molecule deposits for dental/orthopedic implant applications. The first one is a supported vesicular layer (SVL), obtained by liposome adhesion on passivated Ti surface, the second one is a covalently bonded vesicular layer (CBVL) grafted on properly functionalized Ti. Photoluminescence spectroscopy and atomic force microscopy investigations demonstrated the effective anchoring of intact liposomes in both systems. Cytotoxicity assays, performed after 48h, showed a MG63 cell viability higher than 75% and 70% on SVLs and CBVLs, respectively. Scanning electron microscopy investigation revealed numerous and spread MG63 cells after 48h on SVL modified Ti surface and a lower cell adhesion on samples coated with CBVL. The cellular uptake capability of liposome content was proved by fluorescence microscopy using carboxyfluorescein loaded SVLs and CBVLs. Finally, we demonstrated that these liposome-modified Ti surfaces were able to deliver a model bioactive molecule (phosphatidylserine) to adherent cells, confirming the potentiality of developed systems in bone related prosthetic applications.

γ-PGA-coated mesoporous silica nanoparticles with covalently attached prodrugs for enhanced cellular uptake and intracellular GSH-responsive release.

Poor cellular uptake of drug delivery carriers and uncontrolled drug release remain to be the major obstacles in cancer therapy due to their low delivery efficiency. In this study, a multifunctional intracellular GSH (glutathione)-responsive silica-based drug delivery system with enhanced cellular uptake capability is developed. Uniform 50 nm colloidal mesoporous silica nanoparticles (MSNs) with mercaptopropyl-functionalized core and silanol-contained silica surface (MSNs-SHin ) are designed and fabricated as a platform for drug covalent attachment and particle surface modification. Doxorubicin (DOX) with primary amine group as an anticancer model drug is covalently conjugated to the mesopores of MSNs-SHin via disulfide bonds in the presence of a heterobifunctional linker (N-Succinimidyl 3-(2-pyridyldithio) propionate). Poly(γ-glutamic acid) (γ-PGA) can be coated onto the particle surface by sequential electrostatic adsorption of polyethyleneimine (PEI) and γ-PGA. The constructed delivery system exhibits enhanced cellular uptake via a speculated γ-glutamyl transpeptidase (GGT)-mediated endocytosis pathway and controlled drug release capacity via intracellular GSH-responsive disulfide-bond cleavage, and thus significantly inhibits the growth of cancer cells. The multifunctional delivery system paves a new way for developing high-efficient particle-based nanotherapeutic approach for cancer treatment.

Gold nanoparticle-based drug delivery platform for antineoplastic chemotherapy.

Gold nanoparticles (AuNPs) have demonstrated increasingly wide applications in drug delivery due to their unique physicochemical and optical properties as well as low toxicity. Compared to the organic nanocarriers for therapeutic agents, AuNPs have shown superior performance as drug delivery vectors, including the inert nature, well-developed synthesis strategies, tunable size, and flexible and easy surface modification with various chemical and biological molecules. In this review, we emphasize on the applications of AuNPs in the aspect of improving pharmaceutical property and therapeutic efficacy of drugs, especially those covalently and noncovalently connected to the surface of AuNPs. Acting as a solid core to link drugs and their derivatives, AuNPs provide the nano-prodrug system with compressed size, high loading efficiency, three-dimension structure, and enhanced cellular uptake capability. With the intensive and systematical investigation of the drug-connected AuNPs, several important issues will become the hot but emergent topics for future research in this field, such as the toxicity in live human subjects, ultimate destination, and possible pathways and mechanisms for their absorption, circulation, distribution, metabolism, and excretion.

Bioreducible Polypeptide Containing Cell-Penetrating Sequence for Efficient Gene Delivery

To design excellent polypeptide-based gene vectors and determine the gene delivery efficiency. Polypeptides (designated as xPolyK6, xPolyK6-R81 and xPolyK6-R82), comprising the DNA condensing and buffering peptide HK6H as well as cell penetrating peptide (CPP) R8 were obtained by the oxidative polymerization of CHK6HC and CR8C at different molar ratios in 4 mL phosphate-buffered saline (PBS) containing 30% (v/v) DMSO at room temperature for 96 h. The cytotoxicity of vectors was studied by MTT assay. Moreover, particle size, zeta potential and morphology along with the in vitro transfection efficiency and cellular uptake of vector/plasmid DNA (pDNA) complexes were characterized at various w/w ratios to determine their potential in gene therapy. All the vectors presented excellent ability of binding and condensing pDNA, additionally with low cytotoxicity. Simultaneously, transfection efficiency of the vectors appeared apparent dependence on the vector composition. The distinct correlation between the content of CR8C with the transfection efficiency demonstrated the effective improvement in transfection efficacy by the oxidative polymerization. Particularly, xPolyK6-R82 possessed the highest transfection efficiency at a w/w ratio of 50. Furthermore, xPolyK6-R82 also presented the best cellular uptake capability demonstrated by confocal microscopy and flow cytometry. Bioreducible polypeptides incorporating with proper amount of CPP are promising as effective non-viral gene vectors in gene therapy.

Supramolecular Polymers as Dynamic Multicomponent Cellular Uptake Carriers

Supramolecular synthesis represents a flexible approach to the generation of dynamic multicomponent materials with tunable properties. Here, cellular uptake systems based on dynamic supramolecular copolymers have been developed using a combination of differently functionalized discotic molecules. Discotics featuring peripheral amine functionalities that endow the supramolecular polymer with cellular uptake capabilities were readily synthesized. This enabled the uptake of otherwise cell-impermeable discotics via cotransport as a function of supramolecular coassembly. Dynamic multicomponent and multifunctional supramolecular polymers represent a novel and unique platform for modular cellular uptake systems.

Assessment of Water-Soluble π-Extended Squaraines as One- and Two-Photon Singlet Oxygen Photosensitizers: Design, Synthesis, and Characterization

Singlet oxygen sensitization by organic molecules is a topic of major interest in the development of both efficient photodynamic therapy (PDT) and aerobic oxidations under complete green chemistry conditions. We report on the design, synthesis, biology, and complete spectroscopic characterization (vis-NIR linear and two-photon absorption spectroscopy, singlet oxygen generation efficiencies for both one- and two-photon excitation, electrochemistry, intrinsic dark toxicity, cellular uptake, and subcellular localization) of three classes of innovative singlet oxygen sensitizers pertaining to the family of symmetric squaraine derivatives originating from pi-excessive heterocycles. The main advantage of pi-extended squaraine photosensitizers over the large number of other known photosensitizers is their exceedingly strong two-photon absorption enabling, together with sizable singlet oxygen sensitization capabilities, for their use at the clinical application relevant wavelength of 806 nm. We finally show encouraging results about the dark toxicity and cellular uptake capabilities of water-soluble squaraine photosensitizers, opening the way for clinical small animal PDT trials.

The cyto- and genotoxicity of organotin compounds is dependent on the cellular uptake capability

Organotin compounds have been widely used as stabilizers and anti-fouling agents with the result that they are ubiquitously distributed in the environment. Organotins accumulate in the food chain and potential effects on human health are disquieting. It is not known as yet whether cell surface adsorption or accumulation within the cell, or indeed both is a prerequisite for the toxicity of organotin compounds. In this study, the alkylated tin derivatives monomethyltin trichloride (MMT), dimethyltin dichloride (DMT), trimethyltin chloride (TMT) and tetramethyltin (TetraMT) were investigated for cyto- and genotoxic effects in CHO-9 cells in relation to the cellular uptake. To identify genotoxic effects, induction of micronuclei (MN), chromosome aberrations (CA) and sister chromatid exchanges (SCE) were analyzed and the nuclear division index (NDI) was calculated. The cellular uptake was assessed using ICP-MS analysis. The toxicity of the tin compounds was also evaluated after forced uptake by electroporation. Our results show that uptake of the organotin compounds was generally low but dose-dependent. Only weak genotoxic effects were observed after exposure of cells to DMT and TMT. MMT and TetraMT were negative in the test systems. After forced uptake by electroporation MMT, DMT and TMT induced significant DNA damage at non-cytotoxic concentrations. The results presented here indicate a considerable toxicological potential of some organotin species but demonstrate clearly that the toxicity is modulated by the cellular uptake capability.