Facile synthesis of chromium chloride/poly(methyl methacrylate) core/shell nanocapsules by inverse miniemulsion evaporation method and application as delayed crosslinker in secondary oil recovery

Cr(III)ehydrolyzed polyacrylamide(HPAM)gels have been extensively studied as a promising strategy controlling waste water production for mature oilfields.However,the gelation time of the current technologies is not long enough for in-depth placement.In this study,we report a novel synthesis method to obtain chromium chloride/poly(methyl methacrylate)(PMMA)nanocapsules which can significantly delay the gelation of HPAM through encapsulating the chromium chloride crosslinker.The chromium chloride-loaded nanocapsules(CreNC)are prepared via a facile inverse miniemulsion evaporation method during which the hydrophobic PMMA polymers,pre-dispersed in an organic solvent,were carefully controlled to precipitate onto stable aqueous miniemulsion droplets.The stable aqueous nanodroplets(W)containing Cr(III)are dispersed in a mixture of organic solvent(O1)with PMMA and nonsolvent medium(O2)to prepare an inverse miniemulsion.With the evaporation of the O1,PMMA forms CreNCs around the aqueous droplets.The CreNCs are readily transferred into water from the organic nonsolvent phase.The CreNCs exhibit the tunable size(358-983 nm),Cr loading(7.1%-19.1%),and Cr entrapment efficiency(11.7%-80.2%),with tunable zeta potentials in different PVA solutions.The CreNCs can delay release of Cr(III)and prolong the gelation time of HPAM up to 27 days.

Design and synthesis of synthetic promoters for consistency of gene expression across growth phases and scale in S.cerevisiae

Metabolic engineering and synthetic biology endeavors benefit from promoters that perform consistently(or robustly)with respect to cellular growth phase(exponential and stationary)and fermentation scale(microtiter plates,tubes,flasks,and bioreactors).However,nearly all endogenous promoters(especially in Saccharomyces cerevisiae)do not perform in this manner.In this work,a hybrid promoter engineering strategy is leveraged to create novel synthetic promoters with robustness across these conditions.Using a multi-dimensional RNA-seq dataset,promoters with specific phase dependencies were identified.Fragments enriched with functional transcription factors were identified using MEME suite.These motif-containing fragments could impart activity dependence in the opposing condition.Specifically,we obtain two new promoters with high and consistent expression across both phases by increasing the exponential phase activity of the starting stationary-phase scaffold by 38 and 23-fold respectively.Further,we show that these promoters function consistently across various laboratory growth scales over time in a microtiter plate and in flasks.Overall,this work presents and validates a new strategy for engineering promoters in S.cerevisiae with high levels of expression that are robust to cellular growth phase and the scale of the culture.

Designing the new generation of intelligent biocompatible carriers for protein and peptide delivery

Therapeutic proteins and peptides have revolutionized treatment for a number of diseases, and the expected increase in macromolecule-based therapies brings a new set of challenges for the pharmaceutics field. Due to their poor stability, large molecular weight, and poor transport properties,therapeutic proteins and peptides are predominantly limited to parenteral administration. The short serum half-lives typically require frequent injections to maintain an effective dose, and patient compliance is a growing issue as therapeutic protein treatments become more widely available. A number of studies have underscored the relationship of subcutaneous injections with patient non-adherence, estimating that over half of insulin-dependent adults intentionally skip injections. The development of oral formulations has the potential to address some issues associated with non-adherence including the interference with daily activities, embarrassment, and injection pain. Oral delivery can also help to eliminate the adverse effects and scar tissue buildup associated with repeated injections. However, there are several major challenges associated with oral delivery of proteins and peptides, such as the instability in the gastrointestinal(GI)tract, low permeability, and a narrow absorption window in the intestine. This review provides a detailed overview of the oral delivery route and associated challenges. Recent advances in formulation and drugdelivery technologies to enhance bioavailability are discussed, including the co-administration of compounds to alter conditions in the GI tract, the modification of the macromolecule physicochemical properties, and the use of improved targeted and controlled release carriers.

Bone tissue engineering via growth factor delivery:from scaffolds to complex matrices

In recent years,bone tissue engineering has emerged as a promising solution to the limitations of current gold standard treatment options for bone related-disorders such as bone grafts.Bone tissue engineering provides a scaffold design that mimics the extracellular matrix,providing an architecture that guides the natural bone regeneration process.During this period,a new generation of bone tissue engineering scaffolds has been designed and characterized that explores the incorporation of signaling molecules in order to enhance cell recruitment and ingress into the scaffold,as well as osteogenic differentiation and angiogenesis,each of which is crucial to successful bone regeneration.Here,we outline and critically analyze key characteristics of successful bone tissue engineering scaffolds.We also explore candidate materials used to fabricate these scaffolds.Different growth factors involved in the highly coordinated process of bone repair are discussed,and the key requirements of a growth factor delivery system are described.Finally,we concentrate on an analysis of scaffold-based growth factor delivery strategies found in the recent literature.In particular,the incorporation of two-phase systems consisting of growth factor-loaded nanoparticles embedded into scaffolds shows great promise,both by providing sustained release over a therapeutically relevant timeframe and the potential to sequentially deliver multiple growth factors.

Expanding beyond canonical metabolism:Interfacing alternative elements,synthetic biology,and metabolic engineering

Metabolic engineering offers an exquisite capacity to produce new molecules in a renewable manner.However,most industrial applications have focused on only a small subset of elements from the periodic table,centered around carbon biochemistry.This review aims to illustrate the expanse of chemical elements that can currently(and potentially)be integrated into useful products using cellular systems.Specifically,we describe recent advances in expanding the cellular scope to include the halogens,selenium and the metalloids,and a variety of metal incorporations.These examples range from small molecules,heteroatom-linked uncommon elements,and natural products to biomining and nanotechnology applications.Collectively,this review covers the promise of an expanded range of elemental incorporations and the future impacts it may have on biotechnology.

The challenge to improve the response of biomaterials to the physiological environment

New applications of biomaterials often require advanced structures containing synthetic and natural components that are tuned to provide properties unique to a specific application.We discuss how structural characteristics of biomaterials,especially hydrophilic ones,can be used in conjunction with non-ideal thermodynamics to develop advanced medical systems.We show a number of examples of biocompatible,intelligent biomaterials that can be used for organ replacement,biosensors,precise drug delivery over days or weeks,and regenerative medicine.

Surface hydrolysis-mediated PEGylation of poly(N-isopropyl acrylamide)based nanogels

In this work,poly(N-isopropyl acrylamide-co-acrylamide)[P(NIPAAm-co-AAm)]nanogels were modified by hydrolysis above the lower critical solution temperature(LCST)to localize carboxylic acid functional groups at the surface(surface hydrolysis).PNIPAAm copolymerized with 15%and 20%nominal AAm in the feed were prepared and compared to equivalent hydrogels with acrylic acid.The effect and extent of surface hydrolysis was confirmed by potentiometric titration and zeta potential.These surface modified nanogels were then modified with primary amine functionalized PEG chains.Surface hydrolysis-mediated PEGylation had little effect on the swelling response of the nanogels,while also preventing adsorption of model proteins in physiological relevant conditions.While both 15%and 20%AAm gels both decreased protein adsorption,only the 20%AAm gels resulted in fully preventing protein adsorption.The results presented here point to surface hydrolysis as a new route to passivate nanogels for use in vivo.

Design and synthesis of synthetic UP elements for modulation of gene expression in Escherichia coli

Metabolic engineering requires fine-tuned gene expression for most pathway optimization applications.To develop a suitable suite of promoters,traditional bacterial promoter engineering efforts have focused on modifications to the core region,especially the−10 and−35 regions,of native promoters.Here,we demonstrate an alternate,unexplored route of promoter engineering through randomization of the UP element of the promoter—a region that contacts the alpha subunit carboxy-terminal domain instead of the sigma subunit of the RNA polymerase holoenzyme.Through this work,we identify five novel UP element sequences through library-based searches in Escherichia coli.The resulting elements were used to activate the E.coli core promoter,rrnD promoter,to levels on par and higher than the prevalent strong bacterial promoter,OXB15.These relative levels of expression activation were transferrable when applied upstream of alternate core promoter sequences,including rrnA and rrnH.This work thus presents and validates a novel strategy for bacterial promoter engineering with transferability across varying core promoters and potential for transferability across bacterial species.

Opto-thermoelectric pulling of light-absorbing particles

Optomechanics arises from the photon momentum and its exchange with low-dimensional objects.It is well known that optical radiation exerts pressure on objects,pushing them along the light path.However,optical pulling of an object against the light path is still a counter-intuitive phenomenon.Herein,we present a general concept of optical pulling-opto-thermoelectric pulling(OTEP)—where the optical heating of a light-absorbing particle using a simple plane wave can pull the particle itself against the light path.This irradiation orientation-directed pulling force imparts self-restoring behaviour to the particles,and three-dimensional(3D)trapping of single particles is achieved at an extremely low optical intensity of 10^(−2)mWμm^(−2).Moreover,the OTEP force can overcome the short trapping range of conventional optical tweezers and optically drive the particle flow up to a macroscopic distance.The concept of selfinduced opto-thermomechanical coupling is paving the way towards freeform optofluidic technology and lab-on-achip devices.

Re-evaluating the importance of carbohydrates as regenerative biomaterials

Introduction Carbohydrates are the most abundant natural biomaterials in the world.By interacting with cells of a variety of levels,they take part in essential functions of organisms including cellular communication,inflammation,infection development and disease.These carbohydrate–cell interactions occur on a variety of levels through glycoconjugates such as glycolipids,glycosaminoglycans(GAGs),glycoproteins and proteoglycans[1–4].The roles of carbohydrates in biological systems pose them as some of the most sought-after biomaterials.The use of these multifaceted molecules provides the opportunity to tailor desired responses depending on the target application[1–5].

Metabolic pathway engineering

Organisms can be engineered to produce a wide variety of compounds by either enhancing endogenous metabolic pathways,or by introducing exogenous pathways that are either borrowed from other organism,or de novo-designed pathways unknown to nature.While overexpression of bottleneck enzymes and deletion of competing pathways remain at the core of metabolic pathway engineering,there are many other key elements that need to be considered to successfully develop strains for the production of valuable products.

Restructuring the lithium-ion battery:A perspective on electrode architectures

The lithium-ion battery(LIB)has enabled portable energy storage,yet increasing societal demands have moti-vated a new generation of more advanced LIBs.Although the discovery and optimization of battery active ma-terials has been the subject of extensive study since the 1980s,the most disruptive advancements of commercial LIBs in the past decade stem instead from overall cell design and engineering.In pursuit of higher energy density and fast-charging capability,strategies focused on tuning the properties of composite electrode architectures(e.g.,porosity,conductivity,tortuosity,spatial heterogeneity)by restructuring the inactive component matrix of LIB electrode films have recently garnered attention.This perspective explores recent advances in electrode design through an applied lens,emphasizing synthetic platforms and future research directions that are scalable,commercially feasible,and applicable to a wide range of active materials.We introduce and critically assess recently proposed strategies for structuring electrode architectures,including spatial gradients of local compo-sition and microstructure;metal-foil current collector alternatives;and electrode templating techniques,evalu-ating both achievements in battery performance and commercial applicability.Coupled with improved active materials,new electrode architectures hold promise to unlock next generation LIBs.

Recent advances in glucose-responsive insulin delivery systems:novel hydrogels and future applications

Over the past several decades,there have been major advancements in the field of glucose sensing and insulin delivery for the treatment of type I diabetes mellitus.The introduction of closed-loop insulin delivery systems that deliver insulin in response to specific levels of glucose in the blood has shifted significantly the research in this field.These systems consist of encapsulated glucose-sensitive components such as glucose oxidase or phenylboronic acid in hydrogels,microgels or nanoparticles.Since our previous evaluation of these systems in a contribution in 2004,new systems have been developed.Important improvements in key issues,such as consistent insulin delivery over an extended period of time have been addressed.In this contribution,we discuss recent advancements over the last 5 years and present persisting issues in these technologies that must be overcome in order for these systems to be applicable in patients.

Advanced biomedical hydrogels:molecular architecture and its impact on medical applications

Hydrogels are cross-linked polymeric networks swollen in water,physiological aqueous solutions or biological fluids.They are synthesized by a wide range of polymerization methods that allow for the introduction of linear and branched units with specific molecular characteristics.In addition,they can be tuned to exhibit desirable chemical characteristics including hydrophilicity or hydrophobicity.The synthesized hydrogels can be anionic,cationic,or amphiphilic and can contain multifunctional crosslinks,junctions or tie points.Beyond these characteristics,hydrogels exhibit compatibility with biological systems,and can be synthesized to render systems that swell or collapse in response to external stimuli.This versatility and compatibility have led to better understanding of how the hydrogel’s molecular architecture will affect their physicochemical,mechanical and biological properties.We present a critical summary of the main methods to synthesize hydrogels,which define their architecture,and advanced structural characteristics for macromolecular/biological applications.

Observer canonical form based robust fault detection and estimation for hyperbolic spatiotemporal dynamic systems

In this study,the authors propose a novel state and a fault estimation scheme for a class of hyperbolic spatiotemporal dynamic systems in the presence of unknown external disturbance.They consider the occurrence of multiplicative actuator and sensor faults.In detail,they consider two cases of fault occurrence:(i)only one type(actuator or sensor)of fault happens;(ii)two types of faults occur simultaneously.This study discusses the fault detectability conditions by proposing a fault detection observer.To complete the estimation problem,three difficulties arise:(i)no prior information shows the type of faults;(ii)the observer design is non-linear due to multiplication between plant signals(state or input)and unknown fault parameters;(iii)only one boundary measurement is available.They convert the original faulty plant into its observer canonical form.By proposing two filters based on the resulting observer canonical form,they develop novel parameter update laws for fault parameter estimation.With the proposed update laws,the true state of the faulty plant can be estimated by the proposed observers.By selecting appropriate Lyapunov functions,they prove that estimation error of state and fault parameters exponentially decays to an arbitrarily small neighbourhood of zero despite unknown external disturbance.

Bioproduced Proteins On Demand(Bio-POD)in hydrogels using Pichia pastoris

Traditional production of industrial and therapeutic proteins by eukaryotic cells typically requires large-scale fermentation capacity.As a result,these systems are not easily portable or reusable for on-demand protein production applications.In this study,we employ Bioproduced Proteins On Demand(Bio-POD),a F127-bisurethane methacrylate hydrogel-based technique that immobilizes engineered Pichia pastoris for preservable,on-demand production and secretion of medium-and high-molecular weight proteins(in this case,SEAP,α-amylase,and anti-HER2).The gel samples containing encapsulated-yeast demonstrated sustained protein production and exhibited productivity immediately after lyophilization and rehydration.The hydrogel platform described here is the first hydrogel immobilization using a P.pastoris system to produce recombinant proteins of this breadth.These results highlight the potential of this formulation to establish a cost-effective bioprocessing strategy for on-demand protein production.

CRISPR-PIN:Modifying gene position in the nucleus via dCas9-mediated tethering

Spatial organization of DNA within the nucleus is important for controlling DNA replication and repair,genetic recombination,and gene expression.Here,we present CRISPR-PIN,a CRISPR/dCas9-based tool that allows control of gene Position in the Nucleus for the yeast Saccharomyces cerevisiae.This approach utilizes a cohesindockerin interaction between dCas9 and a perinuclear protein.In doing so,we demonstrate that a single gRNA can enable programmable interaction of nuclear DNA with the nuclear periphery.We demonstrate the utility of this approach for two applications:the controlled segregation of an acentric plasmid and the re-localization of five endogenous loci.In both cases,we obtain results on par with prior reports using traditional,more cumbersome genetic systems.Thus,CRISPR-PIN offers the opportunity for future studies of chromosome biology and gene localization.