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α-Amino Acid Pendant Polymers as Endosomal pH-Responsive Gene Carriers
Takuya Wada,Atsushi Maruyama,Arihiro Kano,Naohiko Shimada 한국고분자학회 2012 Macromolecular Research Vol.20 No.3
In order to prepare gene carriers responsive to an endosomal pH, amino groups of linear poly(allylamine)(PAA) or poly(L-lysine) (PLL) were coupled with a-carboxyl groups of α-amino acids (Gly, His, Lys, Arg, and Orn). Acid-base titration indicated that Lys-, Arg-, and Orn-pendant polymers had both strongly basic groups and endosomal pH-responsive α-amino groups. These polymers, like PAA and PLL, formed stable complexes with DNA. Lys-,Arg-, and Orn-pendant polymers were effective transfection reagents independent of the backbone polymers. The pH-responsive α-amino groups enhanced transfection activity as shown by the observation that acetylation of the α-amino group resulted in a considerable loss in transfection activity. These results strongly suggested a lysosomotropic activity of the α-amino groups. Among the α-amino acid-pendant polymers tested, the Orn-pendant polymer exhibited the highest transfection activity/toxicity index. Since PLL with α-amino acid-pendants is composed of naturally occurring amino acids, it is expected to be biodegradable, and these reagents have promise as gene carriers.
Development of Biocompatible Copolymers for Biomedical Application of Controlled Release Systems
김원종,성용길,Atsushi Maruyama,Toshihiro Akaike 한국생체재료학회 2004 생체재료학회지 Vol.8 No.2
The recent development of biocompatible polymers for drug and gene delivery system has been investigated. The use of polymeric drug carriers may extend the retention of drugs in the circulation, which is the main goal in drug design and delivery systems. With the copolymerization of two or three different polymers, the enhanced polymeric drug delivery system shows the physiological properties and targeting efficiency. Even polymeric gene carriers may also overcome the current problems associated with viral vectors in immunogenicity and mutagenesis, there are many obstacles to be overcome for effective polymer-based gene therapy. The recent uses of the copolymeric system to enhance the effectiveness of drug and gene delivery systems have been reported.
Probing the Charge-Transfer Dynamics in DNA at the Single-Molecule Level
Kawai, Kiyohiko,Matsutani, Eri,Maruyama, Atsushi,Majima, Tetsuro American Chemical Society 2011 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.133 No.39
<P>Photoinduced charge-transfer fluorescence quenching of a fluorescent dye produces the nonemissive charge-separated state, and subsequent charge recombination makes the reaction reversible. While the information available from the photoinduced charge-transfer process provides the basis for monitoring the microenvironment around the fluorescent dyes and such monitoring is particularly important in live-cell imaging and DNA diagnosis, the information obtainable from the charge recombination process is usually overlooked. When looking at fluorescence emitted from each single fluorescent dye, photoinduced charge-transfer, charge-migration, and charge recombination cause a “blinking” of the fluorescence, in which the charge-recombination rate or the lifetime of the charge-separated state (τ) is supposed to be reflected in the duration of the off time during the single-molecule-level fluorescence measurement. Herein, based on our recently developed method for the direct observation of charge migration in DNA, we utilized DNA as a platform for spectroscopic investigations of charge-recombination dynamics for several fluorescent dyes: TAMRA, ATTO 655, and Alexa 532, which are used in single-molecule fluorescence measurements. Charge recombination dynamics were observed by transient absorption measurements, demonstrating that these fluorescent dyes can be used to monitor the charge-separation and charge-recombination events. Fluorescence correlation spectroscopy (FCS) of ATTO 655 modified DNA allowed the successful measurement of the charge-recombination dynamics in DNA at the single-molecule level. Utilizing the injected charge just like a pulse of sound, such as a “ping” in active sonar systems, information about the DNA sequence surrounding the fluorescent dye was read out by measuring the time it takes for the charge to return.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2011/jacsat.2011.133.issue-39/ja206325m/production/images/medium/ja-2011-06325m_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja206325m'>ACS Electronic Supporting Info</A></P>
Hiroki Sato,Naohiko Shimada,Atsushi Maruyama 한국고분자학회 2017 Macromolecular Research Vol.25 No.6
We previously reported that graft copolymers comprised of a cationic backbone and abundant grafts of hydrophilic dextran formed soluble interpolyelectrolyte complexes with anionic biopolymers and facilitated self-assembly and folding of the biopolymers, such as duplex formation of DNA and helical folding of a peptide. In this study, effects of the cationic graft copolymers on assembly of gold nanoparticles (AuNPs) and that of DNA on AuNPs were explored. While polylysine homopolymer caused aggregation of AuNP, the graft copolymer did not induce the aggregation as monitored by adsorption spectra. The highly-grafted copolymer at nano molar concentration was capable of suppressing AuNP aggregation induced by 3 M NaCl. Moreover, the copolymer did not cause aggregation of AuNPs whose surface were modified with oligonucleotides (ODN) having highly negative charges. In the presence of copolymer, melting temperature of DNA duplex formed between AuNP-ODN and its complementary ODN was increased about 10 °C, indicating that the copolymer enhanced stability of DNA duplex on the surface of AuNPs. It was concluded that the copolymer selectively promoted assembly of negatively charged DNA but inhibited aggregation of negatively charged AuNPs.
Lee, Yuhan,Lee, Soo Hyeon,Kim, Jee Seon,Maruyama, Atsushi,Chen, Xuesi,Park, Tae Gwan Elsevier 2011 Journal of controlled release Vol.155 No.1
<P><B>Abstract</B></P><P>Development of nano-sized gene delivery vehicles for small interfering RNA (siRNA) delivery is of great importance for their clinical applications such as cancer therapy. Herein, we demonstrate the controlled synthesis of polyethyleneimine (PEI)-coated gold nanoparticles (AuNPs) using catechol-conjugated PEI (PEI-C) for siRNA delivery. Since the conjugated catechol groups are reductive and moderately hydrophobic, PEI-C formed spherical multi-cored micelles in aqueous solution and served as reductive templates for the growth and synthesis of spherical AuNPs with tunable sizes and surface charges. PEI-C was stably anchored on the surface of growing crystal gold seeds with crosslinking, resulting in robust cationic AuNPs. The fabricated PEI-coated AuNPs formed stable complexes with siRNA, and the complexes showed an excellent gene silencing effect in cancer cells. Size and surface charge values of the synthesized AuNPs had a great influence on intracellular uptake and unpacking of siRNA, and the resultant gene silencing efficiency. The PEI-coated AuNPs exhibited an extremely low cytotoxicity due to the reduced density of primary amine groups and the absence of uncomplexed PEI fraction in aqueous solution.</P> <P><B>Graphical Abstract</B></P><P><ce:figure id='f0035'></ce:figure></P>