New Water-Soluble Oxyamino Chitosans as Biocompatible Vectors for Efficacious Anticancer Therapy via Co-Delivery of Gene and Drug

Context-Responsive Nanoparticle Derived from Synthetic Zwitterionic Ionizable Phospholipids in Targeted CRISPR/Cas9 Therapy for Basal-like Breast Cancer

The majority of triple negative breast cancers (TNBCs) are basal-like breast cancers (BLBCs), which tend to be more aggressive, proliferate rapidly, and have poor clinical outcomes. A key prognostic biomarker and regulator of BLBC is the Forkhead box C1 (FOXC1) transcription factor. However, because of its functional placement inside the cell nucleus and its structural similarity with other related proteins, targeting FOXC1 for therapeutic benefit, particularly for BLBC, continues to be difficult. We envision targeted nonviral delivery of CRISPR/Cas9 plasmid toward the efficacious knockdown of FOXC1. Keeping in mind the challenges associated with the use of CRISPR/Cas9 in vivo, including off-targeting modifications, and effective release of the cargo, a nanoparticle with context responsive properties can be designed for efficient targeted delivery of CRISPR/Cas9 plasmid. Consequently, we have designed, synthesized, and characterized a zwitterionic amino phospholipid-derived transfecting nanoparticle for delivery of CRISPR/Cas9. The construct becomes positively charged only at low pH, which encourages membrane instability and makes it easier for nanoparticles to exit endosomes. This has enabled effective in vitro and in vivo downregulation of protein expression and genome editing. Following this, we have used EpCAM aptamer to make the system targeted toward BLBC cell lines and to reduce its off-target toxicity. The in vivo efficacy, biodistribution, preliminary pharmacokinetics, and biosafety of the optimized targeted CRISPR nanoplatform is then validated in a rodent xenograft model. Overall, we have attempted to knockout the proto-oncogenic FOXC1 expression in BLBC cases by efficient delivery of CRISPR effectors via a context-responsive nanoparticle delivery system derived from a designer lipid derivative. We believe that the nonviral approach for in vitro and in vivo delivery of CRISPR/Cas9 targeted toward FOXC1, studied herein, will greatly emphasize the therapeutic regimen for BLBC.

A review of chitosan in gene therapy: Developments and challenges

Gene therapy, as a revolutionary treatment, has been gaining more and more attention. The key to gene therapy is the selection of suitable vectors for protection of exogenous nucleic acid molecules and enabling their specific release in target cells. While viral vectors have been widely used in researches, non-viral vectors are receiving more attention due to its advantages. Chitosan (CS) has been widely used as non-viral organic gene carrier because of its good biocompatibility and its ability to load large amounts of nucleic acids. This paper summarizes and evaluates the potential of chitosan and its derivatives as gene delivery vector materials, along with factors influencing transfection efficiency, performance evaluation, ways to optimize infectious efficiency, and the current main research development directions. Additionally, it provides an outlook on its future prospects.

Controllable Drug-Release Ratio and Rate of Doxorubicin-Loaded Natural Composite Films Based on Polysaccharides: Evaluation of Transdermal Permeability Potential

In drug delivery systems, it is crucial to develop a drug carrier capable of regulating both the drug-release rate and the drug-release ratio. This study proposes a method for controlling the drug-release ratio/rate using doxorubicin-loaded natural composite films composed of polysaccharides (cellulose, chitin, chitosan, or cellulose nanocrystal) and mineral substances (MMT: montmorillonite). We succeeded in controlling the doxorubicin release ratio from 25 to 88% depending on the natural polysaccharide. Likewise, the reduction rate differed depending on the type of natural polysaccharide, whereas the reduction in release was achieved by mixing MMT. Cellulose had the largest reduction in the drug release ratio, approximately 30%, and cellulose nanocrystals showed little change. Furthermore, we conducted a skin permeation test on the natural polysaccharide film with the highest release rate to confirm its transdermal permeability potential. The polysaccharide doxorubicin-loaded film sustainably released doxorubicin for 2 days, which indicated the potential of a carrier for DDS applications.

Structure-activity relationship of drug conjugated polymeric materials against uropathogenic bacteria colonization under in vitro and in vivo settings

The human world has been plagued with different kinds of bacterial infections from time immemorial. The increased development of resistance towards commercial antibiotics has made these bacterial infections an even more critical challenge. Bacteria have modified their mode of interactions with different types of commercial drugs by bringing changes to the receptor proteins or by other resisting mechanisms like drug efflux. Various chemical approaches have been made to date to fight against these smart adapting species. Towards this, we hypothesize chemically modifying the commercial antibacterial drugs in order to deceive the bacteria and destroy the bacterial biomass. In this study, different molecular weight polyethyleneimines are taken and conjugated with some well-known commercial drugs like penicillin and chloramphenicol to explore their antibacterial properties against some of the laboratory and uro-pathogenic strains of Gram-positive and Gram-negative bacteria. A detailed structure-activity relationship of these polymeric prodrug-like materials has been evaluated to determine the optimum formulation. The standardized system not only shows significant ∼90% bacterial killing in liquid broth culture, but also demonstrates promising bacterial inhibition towards biofilm formation for the pathogenic strains on inanimate surfaces like urinary catheters and on an in vivo mouse skin abrasion model. The reported bioactive polymeric materials can be successfully used for widespread therapeutic applications with promising medical relevance.

Current and emerging applications of saccharide-modified chitosan: a critical review

Chitin, as the main component of the exoskeleton of Arthropoda, is a highly available natural polymer that can be processed into various value-added products. Its most important derivative, i.e., chitosan, comprising β-1,4-linked 2-amino-2-deoxy-β-d-glucose (deacetylated d-glucosamine) and N-acetyl-d-glucosamine units, can be prepared via alkaline deacetylation process. Chitosan has been used as a biodegradable, biocompatible, non-antigenic, and nontoxic polymer in some in-vitro applications, but the recently found potentials of chitosan for in-vivo applications based on its biological activities, especially antimicrobial, antioxidant, and anticancer activities, have upgraded the chitosan roles in biomaterials. Chitosan approval, generally recognized as a safe compound by the United States Food and Drug Administration, has attracted much attention toward its possible applications in diverse fields, especially biomedicine and agriculture. Even with some favorable characteristics, the chitosan's structure should be customized for advanced applications, especially due to its drawbacks, such as low drug-load capacity, low solubility, high viscosity, lack of elastic properties, and pH sensitivity. In this context, derivatization with relatively inexpensive and highly available mono- and di-saccharides to soluble branched chitosan has been considered a "game changer". This review critically reviews the emerging technologies based on the synthesis and application of lactose- and galactose-modified chitosan as two important chitosan derivatives. Some characteristics of chitosan derivatives and biological activities have been detailed first to understand the value of these natural polymers. Second, the saccharide modification of chitosan has been discussed briefly. Finally, the applications of lactose- and galactose-modified chitosan have been scrutinized and compared to native chitosan to provide an insight into the current state-of-the research for stimulating new ideas with the potential of filling research gaps.

Core-Shell Structured Chitosan-Polyethylenimine Nanoparticles for Gene Delivery: Improved Stability, Cellular Uptake, and Transfection Efficiency

The delivery of nucleic acids relies on vectors that condense and encapsulate their cargo. Especially nonviral gene delivery systems are of increasing interest. However, low transgene expression levels and limited tolerability of these systems remain a challenge. The improvement of nucleic acid delivery using depolymerized chitosan-polyethylenimine DNA complexes (dCS-PEI/DNA) is investigated. The secore complexes are further combined with chitosan-based shells and functionalized with polyethylene glycol (PEG) and cell penetrating peptides. This modular approach allows to evaluate the effect of functional shell components on physicochemical particle characteristics and biological effects. The optimized ternary complex combines a core-dCS-linear PEI/DNA complex with a shell consisting of dCS-PEG-COOH, which results in improved nucleic acid encapsulation, cellular uptake and transfection potency in human hepatoma HuH-7cells and murine primary hepatocytes. Effects on transgene expression are confirmed in wild-type mice following retrograde intrabiliary infusion. After administration of only 100 ng complexed DNA, ternary complexes induced a high reporter gene signal for three days. It is concluded that ternary coreshell structured nanoparticles comprising functionalized chitosan can be used for in vitro andin vivo gene delivery.

Antioxidant Stress of Transdermal Gene Delivery by Non-Viral Gene Vectors Based on Chitosan-Oligosaccharide

Oxidative stress initiated by reactive oxygen species (ROS) is the cause of many acquired or congenital skin diseases. Oral antioxidants or using topical antioxidants preparations may bring the nonspecific distribution of drugs or anaphylaxis due to repeated use. In this study, a biocompatible gene vector by cross-linking of chitosan-oligosaccharide (CSO) and N,N'-cystamine-bis-acrylamide (CBA) was synthesized (CSO-CBA), which could carry therapeutic genes into the skin, express functional proteins in epidermal cells, and play an efficient antioxidant effect. Infrared and ¹H NMR spectrum data showed that CSO-CBA was successfully synthesized. Gel electrophoresis results showed that the gene could be successfully compressed by the carrier and can be released in a reducing environment. Hemolysis experiments showed that the carrier had good biocompatibility. Transdermal gene delivery experiments proved that the vector can bring genes into the skin, express functional proteins, and protect the skin from reactive oxygen species damage after 7 days of administration. Skin compatibility experiments show that our therapy is biocompatible. Our study provides a minimally invasive and painless, high-biocompatibility, and long-term effective treatment for skin damage caused by reactive oxygen species, which has a potential application.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2019-2020

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2020. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. The review is basically divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of arrays. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other areas such as medicine, industrial processes and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. The reported work shows increasing use of incorporation of new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented nearly 40 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show little sign of diminishing.

Synthesis of NMOF-5 Using Microwave and Coating with Chitosan: A Smart Biocompatible pH-Responsive Nanocarrier for 6-Mercaptopurine Release on MCF-7 Cell Lines

Cancer is one of the most difficult diseases to treat, threatening the lives of millions of people today. So far, various methods have been used to treat cancer, each having its drawbacks. One of these methods is treatment with anticancer drugs, which unfortunately have severe side effects. One of the causes of these complications is the nonspecific effects of anticancer drugs, which attack normal cells in addition to cancer cells and damage healthy tissues. In this study, we are trying to reduce the side effects and increase the efficacy of the drug by providing smart drug delivery. The metal-organic framework (MOF) was rapidly synthesized using a microwave method and at the nanoscale. The particle size of NMOF-5 was 18-20 nm, and its surface area was 2690 m²·g^-1. A chitosan polymer coating was formed on the nanocarrier after 6-mercaptopurine was introduced. The biocompatible nanocarrier exhibited a high capacity to adsorb the drug. The biocompatible nanocarrier slowly and uniformly released 96.78% of the drug in a simulated solution at pH 5 and 20.52% at pH 7.4. This showed that CS-6-MP-NMOF-5 released the drug smartly and pH-sensitively. The stability of the biocompatible nanocarrier was studied at different pH values and remained stable at pH 5 for up to 48 h. The toxicity study of the MCF-7 cell line at different concentrations for 24 h showed the excellent performance of the biocompatible nanocarrier compared to the free drug in terms of toxicity to breast cancer cells.

Multistage pH-responsive codelivery liposomal platform for synergistic cancer therapy

Background

Small interfering RNA (siRNA) is utilized as a potent agent for cancer therapy through regulating the expression of genes associated with tumors. While the widely application of siRNAs in cancer treatment is severely limited by their insufficient biological stability and its poor ability to penetrate cell membranes. Targeted delivery systems hold great promise to selectively deliver loaded drug to tumor site and reduce toxic side effect. However, the elevated tumor interstitial fluid pressure and efficient cytoplasmic release are still two significant obstacles to siRNA delivery. Co-delivery of chemotherapeutic drugs and siRNA represents a potential strategy which may achieve synergistic anticancer effect. Herein, we designed and synthesized a dual pH-responsive peptide (DPRP), which includes three units, a cell-penetrating domain (polyarginine), a polyanionic shielding domain (ehG)n, and an imine linkage between them. Based on the DPRP surface modification, we developed a pH-responsive liposomal system for co-delivering polo-like kinase-1 (PLK-1) specific siRNA and anticancer agent docetaxel (DTX), D-Lsi/DTX, to synergistically exhibit anti-tumor effect.

Results

In contrast to the results at the physiological pH (7.4), D-Lsi/DTX lead to the enhanced penetration into tumor spheroid, the facilitated cellular uptake, the promoted escape from endosomes/lysosomes, the improved distribution into cytoplasm, and the increased cellular apoptosis under mildly acidic condition (pH 6.5). Moreover, both in vitro and in vivo study indicated that D-Lsi/DTX had a therapeutic advantage over other control liposomes. We provided clear evidence that liposomal system co-delivering siPLK-1 and DTX could significantly downregulate expression of PLK-1 and inhibit tumor growth without detectable toxic side effect, compared with siPLK-1-loaded liposomes, DTX-loaded liposomes, and the combinatorial administration.

Conclusion

These results demonstrate great potential of the combined chemo/gene therapy based on the multistage pH-responsive codelivery liposomal platform for synergistic tumor treatment.

Graphical Abstract

Rational Design of Surface-State Controlled Multicolor Cross-Linked Carbon Dots with Distinct Photoluminescence and Cellular Uptake Properties

We disclose for the first time a facile synthetic methodology for the preparation of multicolor carbon dots (CDs) from a single source barring any chromatographic separations. This was achieved via sequential intraparticle cross-linking of surface abundant carboxylic acid groups on the CDs synthesized from a precursor to control their photoluminescence (PL) spectra as well as affect their degree of cellular internalization in cancer cells. The change in PL spectra with sequential cross-linking was projected by theoretical density functional theory (DFT) studies and validated by multiple characterization tools such as X-ray photoelectron spectroscopy (XPS), PL spectroscopy, ninhydrin assay, etc. The variation in cellular internalization of these cross-linked CDs was demonstrated using inhibitor assays, confocal microscopy, and flow cytometry. We supplemented our findings with high-resolution dark-field imaging to visualize and confirm the colocalization of these CDs into distinct intracellular compartments. Finally, to prove the surface-state controlled PL mechanisms of these cross-linked CDs, we fabricated a triple-channel sensor array for the identification of different analytes including metal ions and biologically relevant proteins.

Preparation of Cationic Amphiphilic Nanoparticles with Modified Chitosan Derivatives for Doxorubicin Delivery

Polymeric micelle-like nanoparticles have demonstrated effectiveness for the delivery of some poorly soluble or hydrophobic anticancer drugs. In this study, a hydrophobic moiety, deoxycholic acid (DCA) was first bonded on a polysaccharide, chitosan (CS), for the preparation of amphiphilic chitosan (CS-DCA), which was further modified with a cationic glycidyltrimethylammounium chloride (GTMAC) to form a novel soluble chitosan derivative (HT-CS-DCA). The cationic amphiphilic HT-CS-DCA was easily self-assembled to micelle-like nanoparticles about 200 nm with narrow size distribution (PDI 0.08–0.18). The zeta potential of nanoparticles was in the range of 14 to 24 mV, indicating higher positive charges. Then, doxorubicin (DOX), an anticancer drug with poor solubility, was entrapped into HT-CS-DCA nanoparticles. The DOX release test was performed in PBS (pH 7.4) at 37 °C, and the results showed that there was no significant burst release in the first two hours, and the cumulative release increased steadily and slowly in the following hours. HT-CS-DCA nanoparticles loaded with DOX could easily enter into MCF-7 cells, as observed by a confocal microscope. As a result, DOX-loaded HT-CS-DCA nanoparticles demonstrated a significant inhibition activity on MCF-7 growth without obvious cellular toxicity in comparison with blank nanoparticles. Therefore, the anticancer efficacy of these cationic HT-CS-DCA nanoparticles showed great promise for the delivery of DOX in cancer therapy.

Novel α-tocopherol-ferrocene conjugates for the specific delivery of transgenes in liver cancer cells under high serum conditions

The delivery of therapeutic genes to a specific organ has drawn significant research attention. Among the pool of various delivery vectors, cationic liposomes (non-viral) are potential candidates for delivering therapeutic genes due to their low immunogenic response. Here, we have developed novel ferrocene-conjugated cationic tocopheryl aggregates as non-viral vectors. These formulations can transfer a reporter gene (pGL3; encoded for luciferase protein) specifically to liver cancer cells (HepG2 and Huh7) instead of non-hepatic cancer cells, such as Caco-2 (human colon carcinoma) and HeLa (cervical cancer) cells. The transfection efficiency (TE) of the optimum liposomal formulation is more significant than commercially available Lipofectamine 2000 (L2K). Notably, it retains its TE under high serum conditions (up to 50% FBS). A coupled effect from conjugated ferrocene and tocopherol in the cationic liposomal formulation might be responsible for the cell-specific delivery and higher serum compatibility. Therefore, the present proposed delivery system may provide a platform for further progress in terms of developing hepatotropic gene delivery systems.

Highly Efficient Encapsulation of Doxorubicin Hydrochloride in Metal-Organic Frameworks for Synergistic Chemotherapy and Chemodynamic Therapy

Iron-based metal-organic frameworks (MOFs) have been reported to have great potential for encapsulating doxorubicin hydrochloride (DOX), which is a frequently used anthracycline anticancer drug. However, developing a facile approach to realize high loading capacity and efficiency as well as controlled release of DOX in MOFs remains a huge challenge. Herein, we synthesized water-stable MIL-101(Fe)-C₄H₄ through a microwave-assisted method. It was found the nano-MOFs acted as nanosponges when soaked in a DOX alkaline aqueous solution with a loading capacity experimentally up to 24.5 wt %, while maintaininga loading efficiency as high as 98%. The mechanism of the interaction between DOX and nanoMOFs was investigated by absorption spectra and density functional theory (DFT) calculations, which revealed that the deprotonated DOX was electrostatically adsorbed to the unsaturated Fe₃OCl(COO)₆·H₂O (named Fe₃ trimers). In addition, the as-designed poly(ethylene glycol-co-propylene glycol) (F127) modified nanoparticles (F127-DOX-MIL) could be decomposed under the stimulation of glutathione (GSH) and ATP. As a result, DOX and Fe(III) ions were released, and they could undergo a Fenton-like reaction with the endogenous H₂O₂ to generate the highly toxic hydroxyl radical (·OH). The in vitro experiments indicated that F127-DOX-MIL could cause remarkable Hela cells inhibition through chemotherapy and chemodynamic therapy. Our study provides a new strategy to design a GSH/ATP-responsive drug-delivery nanosystem for chemo/chemodynamic therapy.

Application of Non-Viral Vectors in Drug Delivery and Gene Therapy

Vectors and carriers play an indispensable role in gene therapy and drug delivery. Non-viral vectors are widely developed and applied in clinical practice due to their low immunogenicity, good biocompatibility, easy synthesis and modification, and low cost of production. This review summarized a variety of non-viral vectors and carriers including polymers, liposomes, gold nanoparticles, mesoporous silica nanoparticles and carbon nanotubes from the aspects of physicochemical characteristics, synthesis methods, functional modifications, and research applications. Notably, non-viral vectors can enhance the absorption of cargos, prolong the circulation time, improve therapeutic effects, and provide targeted delivery. Additional studies focused on recent innovation of novel synthesis techniques for vector materials. We also elaborated on the problems and future research directions in the development of non-viral vectors, which provided a theoretical basis for their broad applications.

RNA-extraction-free nano-amplified colorimetric test for point-of-care clinical diagnosis of COVID-19

The global pandemic of coronavirus disease 2019 (COVID-19) highlights the shortcomings of the current testing paradigm for viral disease diagnostics. Here, we report a stepwise protocol for an RNA-extraction-free nano-amplified colorimetric test for rapid and naked-eye molecular diagnosis of COVID-19. The test employs a unique dual-prong approach that integrates nucleic acid (NA) amplification and plasmonic sensing for point-of-care detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with a sample-to-assay response time of <1 h. The RNA-extraction-free nano-amplified colorimetric test utilizes plasmonic gold nanoparticles capped with antisense oligonucleotides (ASOs) as a colorimetric reporter to detect the amplified nucleic acid from the COVID-19 causative virus, SARS-CoV-2. The ASOs are specific for the SARS-CoV-2 N-gene, and binding of the ASOs to their target sequence results in the aggregation of the plasmonic gold nanoparticles. This highly specific agglomeration step leads to a change in the plasmonic response of the nanoparticles. Furthermore, when tested using clinical samples, the accuracy, sensitivity and specificity of the test were found to be >98.4%, >96.6% and 100%, respectively, with a detection limit of 10 copies/μL. The test can easily be adapted to diagnose other viral infections with a simple modification of the ASOs and primer sequences. It also provides a low-cost, rapid approach requiring minimal instrumentation that can be used as a screening tool for the diagnosis of COVID-19 at point-of-care settings in resource-poor situations. The colorimetric readout of the test can even be monitored using a handheld optical reader to obtain a quantitative response. Therefore, we anticipate that this protocol will be widely useful for the development of biosensors for the molecular diagnostics of COVID-19 and other infectious diseases.

Mussel-inspired in situ fabrication of a photothermal composite hydrogel for MR-guided localized tumor ablation

Photothermal ablation could be considered an effective treatment for tumors, but accurate administration and enrichment of photothermal agents remain a huge challenge. Herein, a mussel-inspired photothermal polymeric hydrogel (PPH) was synthesized through a ferric iron-triggered simultaneous metal–catechol coordination reaction and oxidative polymerization of covalently linked pyrrole. The PPH with rapid gelation (less than 10 s) exhibited high photothermal conversion efficiency (49.3%), which enabled effective hyperthermal therapy in situ. Besides, the introduced iron could be used as a T₂-weighted contrast agent for real-time MR imaging to explore the retention and bio-degradation of PPH in vivo. Overall, our findings evidence that the resultant PPH, which possesses potential application in tumor ablation in situ, and metal–catechol coordination strategy inspired by mussel adhesion may stimulate biomedical hydrogel development.

A mussel-inspired photothermal polymeric hydrogel (PPH) was synthesized has been successfully used in tumor ablation in situ.

Evaluation of Chitosan Derivatives Modified Mesoporous Silica Nanoparticles as Delivery Carrier

Chitosan is a non-toxic biological material, but chitosan is insoluble in water, which hinders the development and utilization of chitosan. Chitosan derivatives N-2-Hydroxypropyl trimethyl ammonium chloride (N-2-HACC) and carboxymethyl chitosan (CMCS) with good water solubility were synthesized by our laboratory. In this study, we synthesized mesoporous SiO₂ nanoparticles by the emulsion, and then the mesoporous SiO₂ nanoparticles were modified with γ-aminopropyltriethoxysilane to synthesize aminated mesoporous SiO₂ nanoparticles; CMCS and N-2-HACC was used to cross-link the aminated mesoporous SiO₂ nanoparticles to construct SiO₂@CMCS-N-2-HACC nanoparticles. Because the aminated mesoporous SiO₂ nanoparticles with positively charged can react with the mucous membranes, the virus enters the body mainly through mucous membranes, so Newcastle disease virus (NDV) was selected as the model drug to evaluate the performance of the SiO₂@CMCS-N-2-HACC nanoparticles. We prepared the SiO₂@CMCS-N-2-HACC nanoparticles loaded with inactivated NDV (NDV/SiO₂@CMCS-N-2-HACC). The SiO₂@CMCS-N-2-HACC nanoparticles as delivery carrier had high loading capacity, low cytotoxicity, good acid resistance and bile resistance and enteric solubility, and the structure of NDV protein encapsulated in the nano vaccine was not destroyed. In addition, the SiO₂@CMCS-N-2-HACC nanoparticles could sustain slowly released NDV. Therefore, the SiO₂@CMCS-N-2-HACC nanoparticles have the potential to be served as delivery vehicle for vaccine and/or drug.

Cancer Stem Cell-Targeted Gene Delivery Mediated by Aptamer-Decorated pH-Sensitive Nanoliposomes

A new pH-responsive cationic co-liposomal formulation was prepared in this study using the twin version of the amphiphile palmitoyl homocysteine, TPHC; natural zwitterionic lipid, DOPE; and cholesterol-based twin cationic lipid, C5C, at specified molar ratios. This co-liposome was further decorated with a newly designed fluorescently tagged, cholesterol-tethered EpCAM-targeting RNA aptamer for targeted gene delivery. This aptamer-guided nanoliposomal formulation, C5C/DOPE/TPHC at 8:24:1 molar ratio, could efficiently transport the genes in response to low pH of cellular endosomes selectively to the EpCAM overexpressing cancer stem cells. This particular observation was extended using siRNA against GFP to validate their transfection capabilities in response to EpCAM expression. Overall, the aptamer-guided nanoliposomal formulation was found to be an excellent transfectant for in vitro siRNA gene delivery.

[12]aneN3-Based Gemini-Type Amphiphiles with Two-Photon Absorption Properties for Enhanced Nonviral Gene Delivery and Bioimaging

Although a plethora of nonviral gene vectors have been developed for potential gene therapy, imageable gemini surfactants with stimuli-responsiveness and high transfection efficiency are still scarce for gene delivery. Herein, three gemini amphiphiles (DEDPP-4/8/12) consisting of an aggregation-induced emission (AIE) central fluorophore: 5,6-diphenylpyrazine-2,3-diester (DEDPP), decorated with triazole-[12]aneN₃ as the hydrophilic moiety and alkyl chains of various lengths as the hydrophobic moiety, were designed and synthesized for trackable gene delivery via optical imaging. All three amphiphiles exhibited ultralow critical micelle concentrations (CMCs) (up to 3.40 × 10^-6 M), prominent two-photon absorption properties, and solvatochromic fluorescence. Gel electrophoresis assays demonstrated that the migration of plasmid DNA was completely retarded after condensation with these gemini amphiphiles at low concentrations (up to 10 μM). In addition, the ester bond in these amphiphiles may facilitate vector degradation and DNA release, in response to esterase and the acidic environment inside cells. Upon self-assembly with DOPE to form liposomes, DEDPP-8/DOPE achieved the best transfection efficiency in four cell lines, and the transfection efficiency of DEDPP-8/DOPE in HeLa cell lines was 23.5-fold higher than that of Lipo2000, which is unusually high for small organic molecule-based nonviral vectors. Furthermore, excellent transfection efficiency of DEDPP-8/DOPE was obtained in the presence of serum, and the red fluorescence protein (RFP) gene was successfully transfected in zebrafish embryos. Both one- and two-photon fluorescence imaging clearly demonstrated the delivery process of plasmid DNA. This study demonstrated that gemini-type amphiphiles composed of a two-photon fluorophore core conjugated with triazole-[12]aneN₃ via an ester bond afforded an unprecedentedly high transfection efficiency with excellent biocompatibility, which may provide new insights for the design and development of multifunctional nonviral gene vectors for imageable gene delivery.

Chitosan Derivatives and Their Application in Biomedicine

Chitosan is a product of the deacetylation of chitin, which is widely found in nature. Chitosan is insoluble in water and most organic solvents, which seriously limits both its application scope and applicable fields. However, chitosan contains active functional groups that are liable to chemical reactions; thus, chitosan derivatives can be obtained through the chemical modification of chitosan. The modification of chitosan has been an important aspect of chitosan research, showing a better solubility, pH-sensitive targeting, an increased number of delivery systems, etc. This review summarizes the modification of chitosan by acylation, carboxylation, alkylation, and quaternization in order to improve the water solubility, pH sensitivity, and the targeting of chitosan derivatives. The applications of chitosan derivatives in the antibacterial, sustained slowly release, targeting, and delivery system fields are also described. Chitosan derivatives will have a large impact and show potential in biomedicine for the development of drugs in future.

Natural tripeptide capped pH-sensitive gold nanoparticles for efficacious doxorubicin delivery both in vitro and in vivo

Nanobiotechnology has been gaining ever-increasing interest for the successful implementation of chemotherapy based treatment of cancer. Gold nanoparticles (AuNPs) capped with a natural pH-responsive short tripeptide (Lys-Phe-Gly or KFG) sequence are presented herein for significant intracellular delivery of an anti-cancer drug, doxorubicin (DOX). A particularly increased apoptotic response has been observed for DOX treatments mediated by KFG-AuNPs when compared with drug alone treatments in various cell lines (BT-474, HeLa, HEK 293 T and U251). Furthermore, KFG-AuNP mediated DOX treatment significantly decreases cell proliferation and tumor growth in a BT-474 cell xenograft model in nude mice. In addition, KFG-AuNPs demonstrate efficacious drug delivery in DOX-resistant HeLa cells (HeLa-DOXR).