The advent of genome editing has transformed the therapeutic landscape for several debilitating diseases, and the clinical outlook for gene therapeutics has never been more promising. The therapeutic ...potential of nucleic acids has been limited by a reliance on engineered viral vectors for delivery. Chemically defined polymers can remediate technological, regulatory, and clinical challenges associated with viral modes of gene delivery. Because of their scalability, versatility, and exquisite tunability, polymers are ideal biomaterial platforms for delivering nucleic acid payloads efficiently while minimizing immune response and cellular toxicity. While polymeric gene delivery has progressed significantly in the past four decades, clinical translation of polymeric vehicles faces several formidable challenges. The aim of our Account is to illustrate diverse concepts in designing polymeric vectors towards meeting therapeutic goals of in vivo and ex vivo gene therapy. Here, we highlight several classes of polymers employed in gene delivery and summarize the recent work on understanding the contributions of chemical and architectural design parameters. We touch upon characterization methods used to visualize and understand events transpiring at the interfaces between polymer, nucleic acids, and the physiological environment. We conclude that interdisciplinary approaches and methodologies motivated by fundamental questions are key to designing high-performing polymeric vehicles for gene therapy.
Antisense oligonucleotides (ASOs) are an important emerging therapeutic; however, they struggle to enter cells without a delivery vehicle, such as a cationic polymer. To understand the role of ...polymer architecture for ASO delivery, five linear polymers and five diblock polymers (capable of self-assembly into micelles) were synthesized with varying cationic groups. After complexation of each polymer/micelle with ASO, it was found that less bulky cationic moieties transfected the ASO more effectively. Interestingly, however the ASO internalization trend was the opposite of the transfection trend for cationic moiety, indicating internalization is not the major factor in determining transfection efficiency for this series. Micelleplexes (micelle-ASO complexes) generally enable higher transfection efficacy as compared to polyplexes (linear polymer-ASO complexes). Additionally, the order of addition of cells and complexes was explored. Linear polyplexes showed better transfection efficiency in adhered cells, whereas micelleplexes delivered the ASO more efficiently when the cells and micelleplexes were added simultaneously. This phenomenon may be due to increased cell-complex interactions as micelleplexes have increased colloidal stability compared to polyplexes. These findings emphasize the importance of polymer composition and architecture in governing the cellular interactions necessary for transfection, thus allowing advancement in the design principles for nonviral nucleic acid delivery formulations.
Here, a novel melt electrospinning method to produce few‐micron and nanometer thick fibers is presented, in which a polymer‐coated wire with a sharp tip is used as the polymer source. The polymer ...coating is melted via Joule heating of the source wire and extracted toward the target via electrostatic forces. The high viscosity and low charge density of polymer melts lower their stretchability in melt. The method relies on confining the Taylor cone and reducing initial jet diameter via concentrated electrostatic fields as a means to reduce the diameter of fibers. As a result, the initial jet diameter and the final fiber diameter are reduced by an order of magnitude of three to ten times, respectively, using wire melt electrospinning compared to syringe‐ and edge‐based electrospinning. The fiber diameter melt electrospun via this novel method is 1.0 ± 0.9 µm, considerably thinner than conventional melt electrospinning techniques. The generation of thin fibers are explained in terms of the electrostatic field around the wire tip, as obtained from finite element analysis (FEA), which controls the size and shape of the melt electrospun jet.
A novel melt electrospinning approach to produce few‐micron and sub‐micron thick fibers from polymer melt is presented. The method relies on confining the Taylor cone and electrospinning jet via concentrated electrostatic fields as a means to reduce the diameter of fibers. The fiber diameter spun via this novel method is 1.0 ± 0.9 µm, considerably thinner than conventional melt electrospinning techniques.
The bacterial cell envelope provides a protective barrier that is challenging for small molecules and biomolecules to cross. Given the anionic nature of both Gram-positive and Gram-negative bacterial ...cell envelopes, negatively charged molecules are particularly difficult to deliver into these organisms. Many strategies have been employed to penetrate bacteria, ranging from reagents such as cell-penetrating peptides, enzymes, and metal-chelating compounds to physical perturbations. While cationic polymers are known antimicrobial agents, polymers that promote the permeabilization of bacterial cells without causing high levels of toxicity and cell lysis have not yet been described. Here, we investigate four polymers that display a cationic poly(2-(dimethylamino)ethyl methacrylate (
) block for the internalization of an anionic adenosine triphosphate (ATP)-based chemical probe into
and
. We evaluated two polymer architectures, linear and micellar, to determine how shape and hydrophobicity affect internalization efficiency. We found that, in addition to these reagents successfully promoting probe internalization, the probe-labeled cells were able to continue to grow and divide. The micellar structures in particular were highly effective for the delivery of the negatively charged chemical probe. Finally, we demonstrated that these cationic polymers could act as general permeabilization reagents, promoting the entry of other molecules, such as antibiotics.
It works ether way: Labile adducts of dialkyl ethers with the electrophilic borane B(C6F5)3 are shown to scramble HD to H2 and D2 and catalyze the hydrogenation of 1,1‐diphenylethylene.
The timing of definitive fixation for major fractures in patients with multiple injuries is controversial. To address this gap, we randomized patients with blunt multiple injuries to either initial ...definitive stabilization of the femur shaft with an intramedullary nail or an external fixateur with later conversion to an intermedullary nail and documented the postoperative clinical condition.
Multiply injured patients with femoral shaft fractures were randomized to either initial (<24 hours) intramedullary femoral nailing or external fixation and later conversion to an intramedullary nail. Inclusion: New Injury Severity Score >16 points, or 3 fractures and Abbreviated Injury Scale score > or =2 points and another injury (Abbreviated Injury Scale score > or =2 points), and age 18 to 65 years. Exclusion: patients in unstable or critical condition. Patients were graded as stable or borderline (increased risk of systemic complications).
: Incidence of acute lung injuries.
Ten European Centers, 165 patients, mean age 32.7 +/- 11.7 years. Group intramedullary nailing, n = 94; group external fixation, n = 71. Preoperatively, 121 patients were stable and 44 patients were in borderline condition. After adjusting for differences in initial injury severity between the 2 treatment groups, the odds of developing acute lung injury were 6.69 times greater in borderline patients who underwent intramedullary nailing in comparison with those who underwent external fixation, P < 0.05.
Intramedullary stabilization of the femur fracture can affect the outcome in patients with multiple injuries. In stable patients, primary femoral nailing is associated with shorter ventilation time. In borderline patients, it is associated with a higher incidence of lung dysfunctions when compared with those who underwent external fixation and later conversion to intermedullary nail. Therefore, the preoperative condition should be when deciding on the type of initial fixation to perform in patients with multiple blunt injuries.
A series of unsaturated long‐chain‐bridged diferrocenes Fc‐(CH2)n‐CHCH‐(CH2)n‐Fc (4 a–e) was synthesized by means of olefin metathesis. Subsequent catalytic hydrogenation furnished the saturated ...α,ω‐bis‐ferrrocenyl oligoethylene products Fc‐(CH2)m‐Fc (5). Members of both series formed highly ordered laminar structures at the highly oriented pyrolytic graphite (HOPG) solid/liquid interface or on the Ag(110) surface, which were characterized by STM. Details of the structural features of these ordered physisorbed surface assemblies of 4 and 5 were analyzed by comparison with DFT calculations on model systems and with the characteristic packing modes of these systems in the crystal.
Hydrocarbon‐bridged diferrocenes Fc‐(CH2)n‐CHCH‐(CH2)nFc (1) and Fc‐(CH2)m‐Fc (2) with unsaturated and saturated chains have been prepared by olefin metathesis coupling and subsequent catalytic hydrogenation, respectively. Both these series of compounds form highly ordered physisorbed structures at solid/liquid and solid/gas interfaces. The picture shows an STM image of trans‐1 (n=6) on Ag(110).
It works ether way: Labile adducts of dialkyl ethers with the electrophilic borane B(C sub(6)F sub(5)) sub(3) are shown to scramble HD to H sub(2) and D sub(2) and catalyze the hydrogenation of ...1,1-diphenylethylene.
Ether mal ganz anders: Labile Addukte von Dialkylethern und dem elektrophilen Boran B(C6F5)3 bewirken ein Isotopen‐Scrambling von HD zu H2 und D2. Die Addukte katalysieren die Hydrierung von ...1,1‐Diphenylethylen.
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