Release Of Small Molecules Research Articles

Multimechanophore Polymers for Mechanically Triggered Small Molecule Release with Ultrahigh Payload Capacity.

Polymers that release small molecules in response to mechanical force are promising for a variety of applications including drug delivery, catalysis, and sensing. While a number of mechanophores have been developed for the release of covalently bound payloads, existing strategies are either limited in cargo scope or, in the case of more general mechanophore designs, are restricted to the release of one or two cargo molecules per polymer chain. Herein, we introduce a nonscissile mechanophore based on a masked 2-furylcarbinol derivative that enables the preparation of multimechanophore polymers with ultrahigh payload capacity. We demonstrate that polymers prepared via ring-opening metathesis polymerization are capable of releasing hundreds of small-molecule payloads per polymer chain upon ultrasound-induced mechanochemical activation. This nonscissile masked 2-furylcarbinol mechanophore overcomes a major challenge in cargo loading capacity associated with previous 2-furylcarbinol mechanophore designs, enabling applications that benefit from much higher concentrations of delivered cargo.

Development and biological evaluation of smart powder bandage for wound healing and dressing applications

Cutaneous wounds are one of the pressing concerns for healthcare systems globally. With large amounts of water, conventional hydrogels encounter obstacles in effectively delivering small molecules and peptides for wound healing. The surplus water content challenges the stability and sustained release of small molecules and peptides, diminishing their therapeutic efficacy. Our pioneering smart powder bandage, fabricated through freeze-drying, ensures a water content of <1 % during storage. Upon contact with wound exudate, it forms hydrogel layers, thereby optimizing the delivery of peptides. Tailored for thermosensitive peptides such as EGF, this strategy surmounts the limitations of conventional hydrogels, providing a robust platform for efficacious therapeutic delivery in wound healing applications. Developing multifunctional wound dressings with antibacterial, anti-inflammatory, hemostatic, and healing properties is essential to promote wound healing. Therefore, the current investigation reports the development of multifunctional EGF@Silnanom SPB with the above-mentioned properties to promote wound healing using silver nanomix (Silnanom) and bioactive epidermal growth factors (EGF) as active therapeutics. The characterization of smart powder bandage (SPB) revealed that Silnanom were homogeneously dispersed in the entangled polymer network. The multifunctional smart powder bandage exhibited high bacterial inhibition rates against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and rigorous hemocompatibility, cell compatibility, and in vivo studies also confirmed its biocompatibility. Furthermore, multifunctional EGF@Silnanom SPB effectively reduced pro-inflammatory markers, enhanced collagen deposition, promoted angiogenesis, and accelerated wound healing in a full-thickness mouse wound model through the sustained release of Silnanom and EGF. Additionally, the results of hemostasis analysis on the tail amputation mouse model confirmed the hemostasis properties of the EGF@Silnanom SPB. Overall, the multifunctional EGF@Silnanom SPB shows promising potential for skin wound repair, offering a potent and effective solution to the challenges posed by conventional wound dressings.

New Approach to Encapsulation for Controlled Release of Chemical Additives

Summary A new approach for the synthesis of bio-inspired polymer microcapsules used to encapsulate chemical additives and designed for small molecule release and delivery is shown here. The flexibility to design different microcapsules using an emulsion template results in various encapsulated additives for a new polymer technology platform. The base materials for encapsulation are polyaramids that are highly crosslinked membrane shells around an empty core. These empty capsules provide a carefully designed space to site-isolate chemical additives, various encapsulants for encapsulation, and delivery where needed. These microcapsules have demonstrated that after being formed from a simple one-pot synthesis between two immiscible solutions, a new method for encapsulation for applications in ordinary Portland cement is possible. The final product is a free-flowing solid that can be easily added to any fluid application. Experimental results show that when added to a basic cement slurry design, cement responds to the release of a salt accelerant as measured using standard oilfield equipment, like the pressurized consistometer, which measures changes in viscosity and thickening times. In one of many applications, the consistency of cement remains favorable at 20 Bc after adding encapsulated calcium chloride for up to 5 hours, for example. Over time, various capsules caused cement slurries to set at right angles at various thickening times with the controlled release of encapsulated calcium chloride. This new approach for encapsulation is promising for the chemical and energy field.

Fluorinated Iron Metal-Organic Frameworks for Activatable 19F Magnetic Resonance Imaging and Synergistic Therapy of Tumors.

Due to their appealing physiochemical properties, metal-organic frameworks (MOFs) have been widely employed in biomedical fields. In this study, we utilize ferric ions and fluorine-containing organic ligands as both structural and functional units to develop a stimulus-responsive nanoagent, 19FIMOF-TA nanoparticles, for activatable 19F magnetic resonance imaging (MRI) and synergistic therapy of tumors. This nanoagent could respond to excess GSH in a tumor microenvironment, discharging fluorinated organic ligands and reduced ferrous ions. The release of these fluorine-containing small molecules results in boosting of the 19F MRI signals, which could be further enhanced by the photothermal effect of this nanoagent to achieve a responsive cascaded amplification of 19F MRI signals for tumor visualization. Meanwhile, ferroptosis promoted by the ferrous ions leads to significant tumor cell death, which is synergistically aggravated by the photothermal effect. The encouraging results illustrate the promising potential of our nanoagent for effective tumor imaging and combinative cancer therapy.

Plasma S-Evs Mirnas in Pediatric B Lineage Leukemia: Transforming Factors of Bone Marrow Niche

BACKGROUND Pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) and mature B-cell leukemia are characterized by dismal prognosis in case of relapse. Exosomes are crucial small extracellular vesicles (S-EVs) used by cells for intercellular communication, capable to modulate recipient cells through the release of small biological molecules (DNA, RNA, proteins). Tumor derived exosomes play an important role in leukemogenesis, disease progression, and organ invasion, due to their ability to induce molecular and functional changes within the bone marrow microenvironment (BME). Since little is known behind the mechanism used by leukemic cells to sustain tumor progression through exosomes release, this has become an exciting area to be investigated. OBJECTIVES This study aimed to provide novel insight about S-EVs-mediated small-RNA (sRNA) transfer within tumor niche and clarify how the crosstalk between tumor cells and cells from the microenvironment promote leukemia cells survival and progression. The characterization of leukemic S-EVs cargo led to the identification of new potential biomarkers of disease progression and treatments efficacy. DESIGN/METHODS RNA from plasma S-EVs samples of 17 mature B-cell leukemia, 16 BCP-ALL at diagnosis and 8 healthy donors (HD) were isolated and small-RNA sequencing on Illumina platform was performed; data were analyzed by miR&amp;moRe2 pipeline. MiRNAs levels were quantified by qRT-PCR in an extended cohort including HDs and patients both at diagnosis and during treatment. Mesenchymal stroma cells (MSCs) derived from healthy BM were co-cultured with tumor cell lines by using transwell. MSCs were also directly treated with S-EVs isolated from mature B-cell leukemia and BCP-ALL cell lines. S-EVs exchange was detected by confocal microscopy. Cell viability, migration and adipocyte differentiation assays were then assessed. Finally, pharmacological treatment of tumor cells co-cultured or not with adipocytes was administered. RESULTS Analysis of the profile of sRNAs contained in plasma exosomes according to sRNA-sequencing showed a peculiar miRNA cargo in both BCP-ALL and mature B cell leukemia groups compared to HD, and revealed 15 and 40 sRNAs significantly deregulated, respectively. We prioritized and validated the upregulation of 6 miRNAs (3 in BCP-ALL and 3 in mature B-cell leukemia) in an enlarged cohort patients' S-EVs obtained at diagnosis and in reference cell lines. Of note, the expression of these miRNAs during follow-up significantly decreases, suggesting their tumor origin and corroborating their usefulness as tumor biomarkers. To sustain this hypothesis sRNA-seq data were integrated with gene expression profiles obtained from leukemia blasts, underlining the tumor origin of these miRNAs. The prediction analysis of the miRNAs-target genes highlighted the alteration of specific networks related to cell survival, migration and cell differentiation. Furthermore, we demonstrated the communication via exosome release between leukemic cells and the surrounding cells and how S-EVs play a crucial role in the modulation of BME components. In particular, treatment with tumor derived S-EVs increases MSCs migration ability and prompts their adipogenic differentiation. These results were also confirmed by prioritized miRNAs transfection in MSCs. Co-culture of leukemic cells with adipocytes demonstrated their ability to protect BCP-ALL and mature B-cell leukemia cell lines from chemotherapy: leukemia cells showed a decrease in cell proliferation and a reduction of apoptosis. In line, poor responders BCP-ALL patients showed at diagnosis a positive enrichment in their transcriptome of mechanisms related to adipogenesis and lipids beta-oxidations. CONCLUSIONS Our data demonstrated that leukemic cells and BM niche cells efficiently communicate between each other through S-EVs release and uptake, inducing MSCs rewiring, with enhanced migratory and differentiative properties in vitro. We noted a strong enrichment of common pathways stroked by all the miRNA validated and related to lipid metabolism and sustenance of adipogenesis. Our study demonstrated that the bone marrow modulation is due to leukemic miRNAs shuttled by S-EVs in MSC cells and that the BME rewiring prompt leukemia chemoresistance.

Effects of uniaxial tensile strain on the release of small molecules from silicone rubber

AbstractSilicone rubber materials may be subject to mechanical strains which can affect the transport properties of small molecules loaded in the materials such as plasticizers and active molecules, hence deteriorating their intended mechanical properties or affecting their performance as carriers of active molecules. Therefore, it is important to understand the effects of mechanical strains on transport of small molecules in the silicone rubber matrix. In this work, silicone rubber sheets loaded with 2 wt% triacetin were stretched and held at four different lengths up to 125% engineering strain. The mass transfer coefficients and diffusion coefficients of triacetin in the strained silicone rubber were determined by monitoring the release of triacetin using headspace gas chromatography–mass spectrometry. It was found that there was no significant change of diffusion coefficient as the applied strain increased, which might result from two microstructure changes that had conflicting effects on diffusion: chain orientation and free volume deformation.

Coumarin Dimer Is an Effective Photomechanochemical AND Gate for Small-Molecule Release.

Stimulus-responsive gating of chemical reactions is of considerable practical and conceptual interest. For example, photocleavable protective groups and gating mechanophores allow the kinetics of purely thermally activated reactions to be controlled optically or by mechanical load by inducing the release of small-molecule reactants. Such release only in response to a sequential application of both stimuli (photomechanochemical gating) has not been demonstrated despite its unique expected benefits. Here, we describe computational and experimental evidence that coumarin dimers are highly promising moieties for realizing photomechanochemical control of small-molecule release. Such dimers are transparent and photochemically inert at wavelengths >300 nm but can be made to dissociate rapidly under tensile force. The resulting coumarins are mechanochemically and thermally stable, but rapidly release their payload upon irradiation. Our DFT calculations reveal that both strain-free and mechanochemical kinetics of dimer dissociation are highly tunable over an unusually broad range of rates by simple substitution. In head-to-head dimers, the phenyl groups act as molecular levers to allow systematic and predictable variation in the force sensitivity of the dissociation barriers by choice of the pulling axis. As a proof-of-concept, we synthesized and characterized the reactivity of one such dimer for photomechanochemically controlled release of aniline and its application for controlling bulk gelation.

A strategic approach towards mass balance investigations in pharmaceutical drug substance release testing: A peculiar out of specification case study encountered during API manufacture

Mass balance in drug substances release testing is a critical quality attribute in pharmaceutical manufacturing that continues to challenge modern analytical characterization. This specific perspective of mass balance is lacking in literature, and the following work addresses the knowledge gap related to this topic by examining an in-depth case study and detailing the systematic investigation into mass imbalance observed during release testing of a small molecule API. The process followed a logical stepwise progression beginning with most probable causes and expanded to more obscure causes that require a deeper examination of the API in question until the undetected impurity in question was finally identified. The discovered impurity was eventually found to be formed from a unique side reaction that led to the formation of API-related oligomer impurities, which had eluded conventional small molecule release testing strategies. Ultimately, the characterization gap was traced back to deficiency in the LC results of the developed API purity methods. More importantly, this gap provides an ideal opportunity to highlight common oversights and pitfalls encountered in early phase pharmaceutical development especially as it relates to the method development of truly representative chromatography methods in the API characterization. The work reflects on the key lessons learned from the highlighted pitfalls that were encountered in this case study and offers strategic insights to guide and to improve the development workflow for drug substance characterization strategies.

Methyl-Branched Liposomes as a Depot for Sustained Drug Delivery.

Inadequate drug loading and control of payload leakage limit the duration of the effect of liposomal drug carriers and may cause toxicity. Here, we report a liposome system as a depot for sustained drug delivery whose design is inspired by the low permeability of Archaeal membranes to protons and solutes. Incorporating methyl-branched phospholipids into lipid bilayers decreased payload diffusion across liposomal membranes, thereby enhancing the drug load capacity by 10-16% and reducing the release of small molecules in the first 24 h by 40-48%. The in vivo impact of this approach was demonstrated by injection at the sciatic nerve. Methyl-branched liposomes encapsulating the anesthetic tetrodotoxin (TTX) achieved markedly prolonged local anesthesia lasting up to 70 h, in comparison to the 16 h achieved with liposomes containing conventional lipids. The present work demonstrates the usefulness of methyl-branched liposomes to enhance liposomal depot systems for sustained drug delivery.

Insights into the carbonization mechanism of bituminous coal-derived carbon materials for lithium-ion and sodium-ion batteries

Despite recent interest in the low-temperature carbonization of coal to prepare disordered carbon materials for the anodes of lithium-ion (LIBs) and sodium-ion batteries (SIBs), the carbonization mechanism is still poorly understood. We selected bituminous coal as the raw material and investigated the chemical, microcrystal, and pore structure changes during the carbonization process from coal to the resulting disordered carbon. These structural changes with temperature below 1 000 °C show an increase in both interlayer spacing (3.69–3.82 Å) and defect concentration (1.26–1.90), accompanied by the generation of a large amount of nano-microporous materials. These changes are attributed to the migration of the local carbon layer and the release of small molecules. Furthermore, a decrease in interlayer spacing and defect concentration occurs between1 000 °C and 1 600 °C. In LIBs, samples carbonized at 1 000 °C showed the best electrochemical performance, with a reversible capacity of 384 mAh g−1 at 0.1 C and excellent rate performance, maintaining 170 mAh g−1 at 5 C. In SIBs, samples carbonized at 1 200 °C had a reversible capacity of 270.1 mAh g−1 at 0.1 C and a high initial Coulombic efficiency of 86.8%. This study offers theoretical support for refining the preparation of carbon materials derived from coal.

Furan Release via Force-Promoted Retro-[4+2][3+2] Cycloaddition.

Mechanophores (mechanosensitive molecules) have been instrumental in the development of various force-controlled release systems. However, the release of functional organic molecules is often the consequence of a secondary (nonmechanical) process triggered by an initial bond scission. Here we present a new mechanophore, built around an oxanorbornane-triazoline core, that is able to release a furan molecule following a force-promoted double retro-[4+2][3+2] cycloaddition. We explored this unprecedented transformation experimentally (sonication) and computationally (DFT, CoGEF) and found that the observed reactivity is controlled by the geometry of the adduct, as this reaction pathway is only accessible to the endo-exo-cis isomer. These results further demonstrate the unique reactivity of molecules under tension and offer a new mechanism for the force-controlled release of small molecules.

Magnetic-Responsive Liposomal Hydrogel Membranes for Controlled Release of Small Bioactive Molecules-An Insight into the Release Kinetics.

This work explores the unique features of magnetic-responsive hydrogels to obtain liposomal hydrogel delivery platforms capable of precise magnetically modulated drug release based on the mechanical responses of these hydrogels when exposed to an external magnetic field. Magnetic-responsive liposomal hydrogel delivery systems were prepared by encapsulation of 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) multilayered vesicles (MLVs) loaded with ferulic acid (FA), i.e., DPPC:FA liposomes, into gelatin hydrogel membranes containing dispersed iron oxide nanoparticles (MNPs), i.e., magnetic-responsive gelatin. The FA release mechanisms and kinetics from magnetic-responsive liposomal gelatin were studied and compared with those obtained with conventional drug delivery systems, e.g., free liposomal suspensions and hydrogel matrices, to access the effect of liposome entrapment and magnetic field on FA delivery. FA release from liposomal gelatin membranes was well described by the Korsmeyer-Peppas model, indicating that FA release occurred under a controlled diffusional regime, with or without magnetic stimulation. DPPC:FA liposomal gelatin systems provided smoother controlled FA release, relative to that obtained with the liposome suspensions and with the hydrogel platforms, suggesting the promising application of liposomal hydrogel systems in longer-term therapeutics. The magnetic field, with low intensity (0.08 T), was found to stimulate the FA release from magnetic-responsive liposomal gelatin systems, increasing the release rates while shifting the FA release to a quasi-Fickian mechanism. The magnetic-responsive liposomal hydrogels developed in this work offer the possibility to magnetically activate drug release from these liposomal platforms based on a non-thermal related delivery strategy, paving the way for the development of novel and more efficient applications of MLVs and liposomal delivery systems in biomedicine.

Designing Site Specificity in the Mechanochemical Cargo Release of Small Molecules.

Mechanical force can trigger the predictable and precise release of small molecules from macromolecular carriers. In this article, based on mechanochemical simulations, we show that norborn-2-en-7-one (NEO), I, and its derivatives can selectively release CO, N2, and SO2 and produce two distinctly different products, A ((3E,5Z,7E)-dimethyl-5,6-diphenyldeca-3,5,7-triene-1,10-diyl bis(2-bromo-2-methylpropanoate)) and B (4',5'-dimethyl-4',5'-dihydro-[1,1':2',1''-terphenyl]-3',6'-diyl)bis(ethane-2,1-diyl) bis(2-bromo-2-methylpropanoate). Site-specific design in the pulling points (PP) ensures that by changing the regioselectivity, either A or B can be exclusively generated. Controlling the rigidity of the NEO scaffold by replacing a 6-membered ring with an 8-membered ring and concomitantly tuning the pulling groups makes it mechanolabile toward the selective formation of B. The diradical intermediate formed during I → A is predicted to be persistent for ∼150 fs. The structural design holds the key to the trade-off between mechanochemical rigidity and lability.

Laponite-Based Nanocomposite Hydrogels for Drug Delivery Applications.

Hydrogels are widely used for therapeutic delivery applications due to their biocompatibility, biodegradability, and ability to control release kinetics by tuning swelling and mechanical properties. However, their clinical utility is hampered by unfavorable pharmacokinetic properties, including high initial burst release and difficulty in achieving prolonged release, especially for small molecules (<500 Da). The incorporation of nanomaterials within hydrogels has emerged as viable option as a method to trap therapeutics within the hydrogel and sustain release kinetics. Specifically, two-dimensional nanosilicate particles offer a plethora of beneficial characteristics, including dually charged surfaces, degradability, and enhanced mechanical properties within hydrogels. The nanosilicate-hydrogel composite system offers benefits not obtainable by just one component, highlighting the need for detail characterization of these nanocomposite hydrogels. This review focuses on Laponite, a disc-shaped nanosilicate with diameter of 30 nm and thickness of 1 nm. The benefits of using Laponite within hydrogels are explored, as well as examples of Laponite-hydrogel composites currently being investigated for their ability to prolong the release of small molecules and macromolecules such as proteins. Future work will further characterize the interplay between nanosilicates, hydrogel polymer, and encapsulated therapeutics, and how each of these components affect release kinetics and mechanical properties.

Design and development of microformulations for rapid release of small molecules and oligonucleotides

A systemic delivery of therapeutics frequently results in sub-optimal exposure of the targeted locus and undesired side effects. To address these challenges, a platform for local delivery of diverse therapeutics by remotely controlled magnetic micro-robots was introduced. The approach involves micro-formulation of active molecules using hydrogels that exhibit wide range of loading capabilities and predictable release kinetics. This work introduces two specific hydrogels based on thiol-maleimide and PEG-PLA-diacrylate chemistries that afford high, reliable and reproducible loading and release of several model molecules including doxorubicin, 25-mer poly-dT oligonucleotide and a 5.4 kBp GFP DNA plasmid. The described formulations are suitable for micro-dosing using both conventional or remote delivery devices.

Hydration-induced Void-containing Hydrogels for Encapsulation and Sustained Release of Small Hydrophilic Molecules.

Efficient encapsulation and sustained release of small hydrophilic molecules from traditional hydrogel systems have been challenging due to the large mesh size of 3D networks and high water content. Furthermore, the encapsulated molecules are prone to early release from the hydrogel prior to use, resulting in a short shelf life of the formulation. Here, we present a hydration-induced void-containing hydrogel (HVH) based on hyperbranched polyglycerol-poly(propylene oxide)-hyperbranched polyglycerol (HPG-PPG-HPG) as a robust and efficient delivery system for small hydrophilic molecules. Specifically, after the HPG-PPG-HPG is incubated overnight at 4 °C in the drug solution, it is hydrated into a hydrogel containing micron-sized voids, which could encapsulate hydrophilic drugs and achieve 100% drug encapsulation efficiency. In addition, the voids are surrounded by a densely packed polymer matrix, which restricts drug transport to achieve sustained drug release. The hydrogel/drug formulation can be stored for several months without changing the drug encapsulation and release properties. HVH hydrogels are injectable due to shear thinning properties. In rats, a single injection of the HPG-PPG-HPG hydrogel containing 8 μg of tetrodotoxin (TTX) produced sciatic nerve block lasting up to 10 hours without any TTX-related systemic toxicity nor local toxicity to nerves and muscles.

Dynamically Visualized Mechano-Responsive Supramolecular Self-Assembly System for Small Molecule Release.

The mechano-responsiverelease of small molecules has received extensive attention in ultrasound (US)-controlled drug release in recent years because it can achieve non-invasive, spatiotemporally controlled precise drug release. However, the vast majority of small molecules mechano-release reported so far are based on polymer systems, which suffer from complex preparations and single mechano-response. Here, an isoguanosine (isoG) visualized mechano-responsive supramolecular self-assembly (isoG-VMRSS) system was successfully constructed by a one-pot reaction. It is completely composed of small molecules, which allows for multiple mechano-responsive releases of isoG (at least 9 times) and ultimately has potential for application in US drug release. A combined experimental-computational approach reveals the supramolecular network structure (formed by the joint action of related metal coordination bonds, boronate ester bonds and hydrogen bonds mediated by isoG) gradually formed inside the system is the underlying internal mechanism. Therefore, it provides a new and effective idea of small molecule release in the field of mechanochemistry.

Nanosilicate-hydrogel microspheres formed by aqueous two-phase separation for sustained release of small molecules

Introduction: Hydrogel microspheres are an attractive option for drug delivery applications due to their ease of injection and potential for tunable controlled delivery. However, their utility is limited due to high initial burst release and rapid overall release, which is especially pronounced for small molecules or small size microspheres. We and others have shown that the addition of two-dimensional nanosilicate (NS) particles to hydrogels can significantly prolong release kinetics from hydrogels while minimizing burst release.Materials and Methods: Here we explored whether NS could modulate release kinetics of small molecules from small size injectable microspheres. Polyethylene glycol (PEG)-based hydrogel microspheres were fabricated via polymer/salt aqueous two-phase separation (ATPS), which is facile, high yield, and scalable, without the need for organic solvents or oils.Results and Discussion: Importantly, NS and acridine orange (AO), a model cationic small molecule, were shown to phase separate into the PEG-rich phase, allowing for successful encapsulation within hydrogel microspheres. The fabricated microspheres were stable, similar in size to red blood cells, and easily injectable. The effect of various fabrication parameters, including the addition of NS and AO, on microsphere size and polydispersity were explored. Release of AO was significantly slowed from PEG-NS microspheres compared to PEG-only microspheres and correlated with NS concentration. Two additional small molecules, the chemotherapeutic doxorubicin (positive charge), and the model small molecule Brilliant Blue FCF (negative charge), were shown to exhibit prolonged release, underscoring the broad utility of the system. The dependence of release kinetics on encapsulated NS concentration allows for tunable and prolonged release of small molecules from an injectable hydrogel delivery device.

Caffeine-induced release of small molecules from DNA nanostructures

Several planar aromatic molecules are known to intercalate between base pairs of double-stranded DNA. This mode of interaction has been used to stain DNA as well as to load drug molecules onto DNA-based nanostructures. Some small molecules are also known to induce deintercalation in double-stranded DNA, one such molecule being caffeine. Here, we compared the ability of caffeine to cause deintercalation of ethidium bromide, a representative DNA intercalator, from duplex DNA and three DNA motifs of increasing structural complexity (four-way junction, double crossover motif, and DNA tensegrity triangle). We found that caffeine impedes the binding of ethidium bromide in all these structures to the same extent, with some differences in deintercalation profiles. Our results can be useful in the design of DNA nanocarriers for intercalating drugs, where drug release can be chemically stimulated by other small molecules.

A Simple Radioassay to Detect Nanoscale Membrane Disruption.

Understanding the mechanisms and kinetics of membrane damage is of interest to researchers in several overlapping fields of biology. In this study, we describe the development and validation of a simple 32PO43- release radioassay used to track nanometer-scale damage to the bacterial cell membrane. Nanoscale membrane damage will result in the release of small cytoplasmic molecules, such as amino acids, sugars, and osmolytes. Our radioassay tracks the release of these molecules using the release of cytoplasmic 32PO43- as a proxy. Our assay can both detect 32PO43- release and track release kinetics in the order of minutes. We demonstrate the use of our radioassay using A. baumannii treated with colistin and Ω76: two agents known to cause membrane damage. Our assay tracks greater membrane damage in A. baumannii treated with both these agents, compared to an untreated control. Our assay fills a niche that is not covered by traditional 51Cr release radioassays and fluorescent staining techniques. Furthermore, our assay can potentially be used to track membrane damage in other membrane systems such as lipid vesicles, animal cells, and organelles.