Outer Block Research Articles

Shear-Thinning Extrudable Hydrogels Based on Star Polypeptides with Antimicrobial Properties.

Hydrogels with low toxicity, antimicrobial potency and shear-thinning behavior are promising materials to combat the modern challenges of increased infections. Here, we report on 8-arm star block copolypeptides based on poly(L-lysine), poly(L-tyrosine) and poly(S-benzyl-L-cysteine) blocks. Three star block copolypeptides were synthesized with poly(S-benzyl-L-cysteine) always forming the outer block. The inner block comprised either two individual blocks of poly(L-lysine) and poly(L-tyrosine) or a statistical block copolypeptide from both amino acids. The star block copolypeptides were synthesized by the Ring Opening Polymerization (ROP) of the protected amino acid N-carboxyanhydrides (NCAs), keeping the overall ratio of monomers constant. All star block copolypeptides formed hydrogels and Scanning Electron Microscopy (SEM) confirmed a porous morphology. The investigation of their viscoelastic characteristics, water uptake and syringe extrudability revealed superior properties of the star polypeptide with a statistical inner block of L-lysine and L-tyrosine. Further testing of this sample confirmed no cytotoxicity and demonstrated antimicrobial activity of 1.5-log and 2.6-log reduction in colony-forming units, CFU/mL, against colony-forming reference laboratory strains of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus, respectively. The results underline the importance of controlling structural arrangements in polypeptides to optimize their physical and biological properties.

Grafting of nonpolar polyisoprene as midblock and polar polylactide as outer block onto cellulose to produce bio-based thermoplastic elastomers

Sustainable cellulose-graft-diblock copolymers (cellulose-graft-polyisoprene-block-polylactide, MCC-g-PI-b-PLLA, MCC was chemically-modified microcrystalline cellulose) were designed and delicately synthesized for the first time by a mild and facile procedure via combining ring-opening polymerization and reversible addition-fragmentation chain transfer polymerization techniques, which conquered the difficulties in synthesis due to the distinct chemical properties among the MCC backbone, PI and PLLA blocks. Two separate glass transition temperatures were detected for MCC-g-PI-b-PLLA copolymers by differential scanning calorimetry, indicative of microphase separation, consistent with small-angle X-ray scattering and atomic force microscopy measurements. The α-form crystals of PLLA outer blocks were revealed by wide-angle X-ray diffraction measurement. The monotonic and step-cyclic tensile tests revealed that the mechanical property could be tuned by changing the molecular mass of PI midblock. The two ends of the soft PI midblock were anchored by rigid cellulose backbone and hard PLLA outer block, respectively, which served as physical crosslinking points. The rigid cellulose backbones brought the PI rubbery domains and PLLA hard domains together to form a whole hierarchical microstructure, endowing the copolymers with distinguished mechanical property. This work provided a feasible approach to producing environmental-friendly cellulose-based copolymers with fully biomass-derived feedstocks, having a profound impact on the development of sustainable polymer-based materials.

Testing the hypothesis of a nested block covariance matrix structure with applications to medicine and natural sciences

This paper addresses the challenge of testing the hypothesis of what the authors call a nested block circular‐compound symmetric (NBCCS) covariance structure for the population covariance matrix. This is a covariance structure which has an outer block compound symmetric structure, where the diagonal blocks are themselves block circular matrices, while the off‐diagonal blocks are formed by all equal matrices. The NBCCS null hypothesis is decomposed into sub‐hypotheses, allowing this way for a simpler way to obtain a likelihood ratio test and its associated statistic. The exact moments of this statistic are derived, and its distribution is carefully examined. Given the complicated nature of this distribution, highly precise near‐exact distributions were developed. Numerical studies are conducted to assess the proximity between these near‐exact distributions and the exact distribution, highlighting the performance of these approximations, even in the case of very small sample sizes. Furthermore, three datasets, on bone mineral content, metabolic rates of glucose, and soil moisture are used to exemplify the practical application of the methodology derived in this study.

Application of Laennec extrathecal blockade combined with indocyanine green fluorescence imaging in laparoscopic anatomic hepatectomy.

To investigate the safety and application value of combining Laennec extracapsular occlusion with ICG fluorescence imaging in laparoscopic anatomic hepatectomy. Complete laparoscopic dissection was performed outside the Laennec sheath, blocking Glisson's pedicle of the corresponding liver segment or lobe. An appropriate amount of indocyanine green (ICG) dye was intravenously injected, and the boundary line between the pre-cut liver segment and liver lobe was identified using fluorescence laparoscopy. Complete resection of the liver segment or lobe was performed based on anatomical markers. Clinical data, including operation time, intraoperative blood loss, postoperative hospital stay, and postoperative complications, were collected. A total of 14 cases were included in the study, including seven cases of primary liver cancer, three cases of metastatic liver cancer, three cases of intrahepatic bile duct calculi, and one case of hepatic hemangioma. All 14 patients underwent anatomic hepatectomy under fluorescent laparoscopy, with four cases involving the right liver, seven cases involving the left liver, two cases involving the right anterior lobe, and one case involving the right posterior lobe. Combining laparoscopic follow-up of the Laennec membrane with Glisson outer sheath block and intraoperative ICG fluorescence imaging provides real-time guidance for locating the resection boundaries during anatomic hepatectomy. This approach helps in controlling intraoperative bleeding, reducing operation time, and ensuring high safety. It holds significant value in clinical application.

One-Component Nanocomposites Made from Diblock Copolymer Grafted Cellulose Nanocrystals.

Cellulose nanocrystals (CNCs) are bio-based, rod-like, high-aspect-ratio nanoparticles with high stiffness and strength and are widely used as a reinforcing nanofiller in polymer nanocomposites. However, due to hydrogen-bond formation between the large number of hydroxyl groups on their surface, CNCs are prone to aggregate, especially in nonpolar polymer matrices. One possibility to overcome this problem is to graft polymers from the CNCs' surfaces and to process the resulting "hairy nanoparticles" (HNPs) into one-component nanocomposites (OCNs) in which the polymer matrix and CNC filler are covalently connected. Here, we report OCNs based on HNPs that were synthesized by grafting gradient diblock copolymers onto CNCs via surface-initiated atom transfer radical polymerization. The inner block (toward the CNCs) is composed of poly(methyl acrylate) (PMA), and the outer block comprises a gradient copolymer rich in poly(methyl methacrylate) (PMMA). The OCNs based on such HNPs microphase separate into a rubbery poly(methyl acrylate) phase that dissipates mechanical energy and imparts toughness, a glassy PMMA phase that provides strength and stiffness, and well-dispersed CNCs that further reinforce the materials. This design afforded OCNs that display a considerably higher stiffness and strength than reference diblock copolymers without the CNCs. At the same time, the extensibility remains high and the toughness is increased up to 5-fold relative to the reference materials.

Novel twofold control for delayed industrial processes with integrating and inverse response characteristics

Non-self- regulating nature of integrating plant causes their regulation a great challenge to researchers. Presence of time delay and positive zero in such processes makes their control more demanding. A novel control technique is developed for such processes to cope with the difficult situations and achieve enhanced performance and robustness. Suggested method is twofold: first the Inner loop controller’s parameters are adjusted to stabilize the process using maximum sensitivity concept and then the outer loop control block is designed by specifying desired setpoint tracking response in the frame of direct synthesis approach involving single tunable parameter. The tunable parameter’s values are obtained so that the robust stability condition is satisfied along with the justification of robust performance constraint in the presence of unstructured uncertainties. The effectiveness of the proposed method is verified on different plants and its advantages over some existing methods are also highlighted. Suggested approach yields improved performance with less control effort and enhanced robustness.

Comparison of two preserved cartilage iliac crest cortical-cancellous bone blocks graft harvesting techniques in children: A prospective, double-blind, randomized clinical trial

PurposeTo compare donor-site morbidity for alveolar bone grafting results following cartilage-preserving outer and inner cortico-cancellous iliac crest (OCIC and ICIC) bone block grafting in children. Materials and methodsPatients were randomly divided into two groups and prospectively reviewed. In the OCIC and ICIC groups, cortico-cancellous bone blocks were harvested at outer and inner iliac crest respectively. Patient characteristics and surgical parameters were compared; pain intensity and duration, lateral femoral cutaneous nerve (LFCN) injury, gait disturbance, scar and contour satisfaction were analysed postoperatively. ResultsForty-nine consecutive patients (OCIC, 24; ICIC, 25) were included. There were no significant differences in patient characteristics or donor-site surgical parameters. The mean pain score on the first post-operative day was significantly lower in the OCIC group (3.75±1.70) than in the ICIC group (5.20±2.08) (p=0.012). The pain duration was similar in the two groups (median: 5 days). Temporary LFCN injury only occurred in 3 patients in the ICIC group. Postoperatively, the duck and circle gaits were observed in the OCIC and ICIC groups, respectively. There were no significant differences in the claudication duration, scar and contour satisfaction between the groups. ConclusionOCIC bone graft harvesting is marginally advantageous in children due to less early postoperative donor-site pain and a lower risk of nerve damage.

Nanostructures, Linear Rheological Responses, and Tunable Mechanical Properties of Microphase-Separated Cellulose-graft-Diblock Bottlebrush Copolymer Elastomers.

A series of cellulose-graft-diblock bottlebrush copolymer elastomers (cellulose-graft-poly(n-butyl acrylate)-block-poly(methyl methacrylate) (Cell-g-PBA-b-PMMA)) with short side chains were synthesized via successive atom transfer radical polymerization (ATRP) to study the influence of varying compositions and lengths of the graft diblock side chains on microphase morphologies and properties. The microphase-separated morphologies from misaligned spheres to cylinders were observed by atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) measurements. These bottlebrush copolymer elastomers possessed thermal stability and enhanced mechanical properties because the PMMA outer block could self-assemble into hard microdomains, which served as physical cross-links. The viscoelastic responses of these bottlebrush copolymers within the linear viscoelastic (LVE) regime were carried out by the oscillatory shear rheology. The time-temperature superposition (tTs) principle was applied to construct the master curves of the dynamic moduli, and the sequential relaxation of dense bottlebrush copolymers with different PMMA hard outer block lengths was analyzed. The rheological behaviors in this work could be utilized to build up the connection of microstructures and properties for the application of these bottlebrush copolymers as high-performance thermoplastic elastomers.

Subduction transition and relation to upper plate faults revealed by the 2019 Mw 6.0 and 6.2 Costa Rica-Panama border earthquakes

We study the May 12, 2019, Mw 6.0 (hereafter Laurel earthquake) and a June 26, 2019, Mw 6.2 (hereafter Manaca earthquake) earthquakes located in a complex strike-slip to subduction transition zone in the Costa Rica-Panama border using a dense local network of broadband and strong-motion instruments, concluding that the Laurel mainshock data (hypocenter, centroid, and focal mechanism), concurrently with its aftershock distribution, indicate an almost vertical north-south oriented, dextral strike-slip fault. This fault ruptured at depths between 10 and 30 km in the lower crust of Panama Microplate and the geometry implies a shallow influence of the Panama fracture zone. Meanwhile, for the Manaca earthquake, the aftershocks are concentrated on a 25 km long NW-SE trend, with a depth between 20 and 45 km. One of the nodal planes of the focal mechanism of the Manaca earthquake, as well as the centroid location coincides with the aftershock locations trend, supporting the hypothesis that a nearby steeply dipping sinistral strike-slip fault originated this event. Earthquake locations and focal mechanism analyses of collected data from global and local earthquake catalogs suggest that the strong coupling caused by the subduction of the Cocos Ridge and Nazca plate is largely accommodated by outer arc crustal block migration with a combination of NW-SE sinistral and N-S dextral strike-slip faults deforming the overriding Panama Microplate. Sinistral motion of crustal blocks, on the Costa Rica side, are consistent with observed motions along with the Azuero-Sona fault system and Coiba Faults on the Panamanian side.

Design and testing of a DNA-like torsional structure for energy absorption

A torsional structure with a DNA-like chiral core is proposed and investigated for energy absorption with a frictional mechanism. The DNA-like chiral core can generate a twisting deformation under axial loading. Based on this behavior, the proposed torsional structure exhibits a unique energy absorption capacity by structural collapse and torsion-induced friction. Additive manufacturing is used to prepare five sets of metal specimens with the new DNA-like chiral core structure. A series of quasi-static compression experiments are carried out to obtain the compressive stress–strain relationship and induced twisting angle of our designed structure. The experimental results show distinct energy absorption mechanism and effectiveness of the design which are subsequently used to validate the finite element simulation. The results of the experiment and numerical analysis show that the torsional friction between the top cap of the structure and the outer block can absorb around 10% of the total compression energy input. Furthermore, geometry parametric studies are conducted to investigate the effects of design parameters on energy absorption property of the proposed structure.

Identification Codes: A Topical Review With Design Guidelines for Practical Systems

A wide range of information technology applications require the identification of a particular message or label that represents the identity of an object at a distance, e.g., over a wireless channel. Conventionally, the underlying information that represents the identity is transmitted over the channel, following the information-theoretic concept of message transmission. If the purpose of the interaction over the channel is only to verify (match) an identity, then the concept of identification over channels—utilizing the identification codes that have been developed by the information theory community—can provide an exponential efficiency gain over message transmission. This topical review article conducts for the first time a comprehensive detailed evaluation of the existing identification codes for the practically relevant regime of finite parameters. We examine essentially all published identification codes, including codes based on inner constant weight codes that are concatenated with outer linear block codes, such as Reed-Solomon and Reed-Muller codes. Specifically, we conduct a holistic identification code comparison based on the logarithm of the number of representable identities (in shannon), the size (in bit) of the transmitted cue that represents an identity, and the corresponding type II error probability bound for essentially all existing identification codes. Based on the resulting insights, we formulate guidelines for the design of practical (finite-parameter) identification codes. For instance, we find that a linear block code (without concatenation with a sophisticated inner constant-weight code) is sufficient for most practical identification code usages.

Hybridization of NSGA-II and MILP for optimization of the location of electric-scooters sharing-stations

TA crucial aspect of the proper functioning of bikes and electric scooters sharing systems is the correct locationand dimensioning of the sharing stations. The resolution of the previous problem is carried out based on the maximization of coverage or the minimization of costs, but the two objectives are not usually treated at the same time.In this work, we propose a method based on the hybridization of the popular Elitist Non-Dominated Sorting Genetic Algorithm (NSGA- II) with a Mixed-Integer Linear Programming (MILP) model to approximate the Pareto Frontier of the problem. This allows the decision-maker a greater understanding of the range of possible options. The NSGA-II plays the role of an outer block that deals with the selection and sizing of each of sharing stations. The MILP model is an inner block that calculates the associated coverage of that solution. The schema was compared with an adaptative-weighting algorithm, reaching the hybridization of NSGA-II and MILP a better coverage of the Pareto Frontier.

Systematic Study of Enzymatic Degradation and Plasmid DNA Complexation of Mucus Penetrating Star-Shaped Lysine/Sarcosine Polypept(o)ides with Different Block Arrangements.

8-Arm star polypep(o)ides comprising cationic polylysine and hydrophilic polysarcosine blocks with a degree of polymerization (DP) of 30 per block are synthesized. Two different block sequences with polylysine as the inner and polysarcosine as the outer block and vice versa are obtained in addition to a statistical copolymer. Analysis of the enzymatic hydrolysis by the proteolytic enzyme trypsin demonstrates a strong dependence on structural arrangements. While polypept(o)ide disintegration is detectible after 24h by Size Exclusion Chromatography (SEC), significant hydrolysis of the lysine blocks is only monitored after 48h by fluorescamine labeling of the produced lysine and clearly accelerated in structures with more accessible polylysine blocks. All structures are capable of complexing plasmid DNA and form gene nanomedicines at sizes around or below 200nm as determined by Dynamic Light Scattering (DLS), Nanoparticle Tracking Analysis (NTA), and Transition Electron Microscopy (TEM). The polyplex formation is slightly enhanced for both block structures over the random copolypept(o)ide. Moreover, it is demonstrated that the polyplexes can transport through mucus. The results highlight the importance of structural control in compartmentalized polymeric gene vector candidates with hydrophilic domains for potential mucosal delivery.

Potential of Graft Polymers Bearing Inner Molten Block and Outer Glassy Block at the Graft Chains for Thermoplastic Elastomers with Enhanced Properties

AbstractThe authors here demonstrate some significant benefits of using graft polymers with inner molten block and outer glassy block at the graft chains (Graft‐Block polymer) for thermoplastic elastomers. The synthesis of the target Graft‐Block polymer is made by combining two types of living radical polymerization, reversible addition‐fragmentation chain transfer polymerization and atom transfer radical polymerization. Temperature ramp rheology, tensile tests, and load‐unload cycle tests indicate that the Graft‐Block polymer‐based elastomers have significantly improved thermal stability and mechanical properties when compares to the Triblock copolymer‐based analog. The enhanced properties are discussed in terms of the effective network strands that connected the different glassy hard domains and the presence of abundant junction points in the molten strand matrix. Overall, this research presents clear experimental evidence of such graft polymers' high potential for application as thermoplastic elastomers.

A correlation-breaking interleaving of polar codes in concatenated systems

It is known that the bit errors of polar codes with successive cancellation (SC) decoding are coupled. However, existing concatenation schemes of polar codes with other error correction codes rarely take this coupling effect into consideration. To achieve a better error performance of concatenated systems with polar codes as inner codes, one can divide all bits in an outer block into different polar blocks to completely de-correlate the possible coupled errors in the transmitter side. We call this interleaving a blind interleaving (BI) which serves as a benchmark. Two BI schemes, termed BI-DP and BI-CDP, are proposed in the paper. To better balance performance, memory size, and the decoding delay from the de-interleaving, a novel interleaving scheme, named the correlation-breaking interleaving (CBI), is proposed. The CBI breaks the correlated information bits based on the error correlation pattern proposed and proven in this paper. The proposed CBI scheme is general in the sense that any error correction code can serve as the outer code. In this paper, Low-Density Parity-Check (LDPC) codes and BCH codes are used as two examples of the outer codes of the interleaving scheme. The CBI scheme 1) can keep the simple SC polar decoding while achieving a better error performance than the state-of-the-art (SOA) direct concatenation of polar codes with LDPC codes and BCH codes; 2) achieves a comparable error performance as the BI-DP scheme with a smaller memory size and a shorter decoding delay. Numerical results are provided to verify the performance of the BI schemes and the CBI scheme.

Shape-Changing Bottlebrush Polymers.

Bottlebrush polymers (BBPs), composed of relatively short polymeric side chains densely grafted on a polymer backbone, exhibit many unique characteristics and hold promise for a variety of applications. This Perspective focuses on environmentally induced shape-changing behavior of BBPs at interface and in solution, particularly worm/star-globule shape transitions. While BBPs with a single type of homopolymer or random copolymer side chains have been shown to undergo pronounced worm-to-globule shape changes in response to external stimuli, the collapsed brushes are unstable and prone to aggregation. By introducing a second, solvophilic polymer into the side chains, either as a distinct type of side chain or as the outer block of block copolymer side chains, the collapsed brushes not only are stabilized but also create unimolecular micellar nanostructures, which can be used for, e.g., encapsulation and delivery of substances. The current challenges in the design, synthesis, and characterization of stimuli-responsive shape-changing BBPs are discussed.

Unconventional Approach to Fabricating a TiO2 Nanoring with Precise Dimension Control Based on Starlike Polymeric Nanoreactors.

The past few years witnessed the rapid development of bottom-up synthesis strategies for preparing various nanostructures (i.e., nanoparticles, nanorods, nanowires, etc.) with distinct morphology-dependent properties. In this study, we reported a facile and efficient synthesis method for preparing anatase titanium dioxide (TiO2) nanorings based on multiarm, starlike amphiphilic polystyrene-b-poly(acrylic acid) (PS-b-PAA) diblock copolymers as nanoreactors which were prepared via a sequential atom-transfer radical polymerization (ATRP) technique followed by the conversion of polystyrene-b-poly(tert-butyl acrylate) (PS-b-PtBA) to PS-b-PAA. The outer PAA block of nanoreactors possessed carboxylic acid groups which could coordinate with a titanium precursor followed by high-temperature calcination to form crystalline TiO2 nanorings. The living nature of ATRP enabled the precise preparation of starlike diblock copolymer nanoreactors with a controlled length of each block (i.e., PtBA and PS), thereby tailoring the inner diameter and wall thickness of the resulting TiO2 nanorings, which were inaccessible to conventional routes.

Diblock copolymers directing construction of hierarchically porous metal-organic frameworks for enhanced-performance supercapacitors

A rationally designed strategy is developed to synthesize hierarchically porous Fe-based metal-organic frameworks (P-Fe-MOF) via solution-based self-assembly of diblock copolymers. The well-chosen amphiphilic diblock copolymers (BCP) of polystyrene-block-poly(acrylic acid) (PS-b-PAA) exhibits outstanding tolerance capability of rigorous conditions (e.g. strong acidity or basicity, high temperature and pressure), steering the peripheral crystallization of Fe-based MOF by anchoring ferric ions with outer PAA block. Importantly, the introduction of BCP endows MOF materials with additional mesopores (∼40 nm) penetrating whole crystals, along with their inherent micropores and introduced macropores. The unique hierarchically porous architecture contributes to fast charge transport and electrolyte ion diffusion, and thus promotes their redox reaction kinetics processes. Accordingly, the resultant P-Fe-MOF material as a new electrode material for supercapacitors delivers the unprecedented highest specific capacitance up to 78.3 mAh g−1 at a current density of 1 A g−1, which is 9.8 times than that of Fe-based MOF/carbon nanotubes composite electrode reported previously. This study may inspire new design of porous metal coordination polymers and advanced electrode materials for energy storage and conversion field.

Relationship between crystallization state and degradation behavior of poly(l‐lactide)/four‐armed poly(d,l‐lactide)‐block‐poly(d‐lactide) blends with different poly(d‐lactide) block lengths

AbstractA series of four‐armed poly(d,l‐lactide)‐block‐poly(d‐lactide) (4‐DL‐D) copolymers were synthesized by ring‐opening polymerization. By fixing the poly(d,l‐lactide) (PDLLA) block length (1 kg mol−1) and changing the poly(d‐lactide) (PDLA) block length (Mn,PDLA = 0, 0.5, 1.1, 1.3, 1.8 and 2.6 kg mol−1), the crystallization and alkaline degradation of the PLLA/4‐DL‐D blends were investigated. The four‐armed PDLLA core of the copolymer inhibited the crystallization of PLLA, while the outer PDLA block could affect the crystallization differently when its length changed. If Mn,PDLA was 0 or 0.5 kg mol−1, the crystallization of PLLA in the PLLA/4‐DL‐D blend was retarded markedly and the degradation rate of the blend films was much faster than that of neat PLLA film. Interestingly, when Mn,PDLA was 1.1 kg mol−1 or higher, stereocomplex (SC) crystallites with different morphologies were formed, and the degradation rate of the PLLA/4‐DL‐D blend decreased gradually with increasing Mn,PDLA. In the PLLA/4‐DL‐D1.1 blend, the SC crystallites acted as nucleators for PLLA homocrystallites, while in the PLLA/4‐DL‐D1.3 blend, small isolated SC crystallites were observed inside the PLLA homospherulites. When Mn,PDLA was 1.8 or 2.6 kg mol−1, a network structure of SC crystallites was formed and the degradation resistance of the films was markedly enhanced. A possible isothermal crystallization mechanism was proposed for the PLLA/4‐DL‐D blends, and the relationship between the crystallization state and degradation behavior was explored. This work revealed that the crystallization state, which was controlled by the PDLA block length, had a significant effect on the degradation behavior of PLLA/4‐DL‐D blend films. © 2020 Society of Chemical Industry

Using coarse-grained models to examine structure-property relationships of diblock-arm star polymers

Molecular dynamics simulations were used to verify that diblock-arm star polymers (SPs) can be accurately described using coarse-grained models. Each arm of the SPs examined consist of an inner polyethylene block and an outer polyethylene oxide block. A sixteen-arm SP with arm chemistry -CH224-CH2OCH26-H was mapped to a MARTINI coarse-grained representation and compared to results from atomistic simulations of an identical chemistry and architecture. Results for radius of gyration, radial distribution functions, and occupied volumes all show agreement with the atomistic model and reproduce general trends with respect to temperature. Additional measurements of interfacial area and anisotropy reveal that our model does not demonstrate crystallization of the polyethylene blocks at low temperatures as observed in the atomistic model which can be ascribed to the reduction in degrees of freedom that follow from coarse-graining. Calculated values for relaxation times agree with the general trends from the atomistic simulations. Nineteen additional coarse-grained star polymers were examined in order to investigate structure-property relationships that arise by varying arm number and arm length. The ability to model these chemical species at this resolution will allow for simulations of polymeric nanocarriers in more complex environments including at increased concentrations and near surfaces. This work demonstrates an important first step in work that will enable improved design of these polymeric nanoparticles for drug delivery applications.