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Polymeric nanofibers have been widely used as scaffolds for tissue engineering, drug delivery, and filtration applications, among many others. This work describes new methods to modify chemically-inert fibers using PET-RAFT.

Recent developments of highly expandable foaming pre-polymer resins for lithographic additive manufacturing have allowed for the creation of structures larger than a printer's build envelope. To fully utilize the capabilities of this technology, the mechanical properties of these foams must be improved. This manuscript presents one method for strengthening these lightweight polymeric structures via aerosol spray application of a high-strength, low-viscosity photocurable coating. This method is free from the reliance on often complex, large, or bulky on-site equipment ordinarily required by conventional high-strength spray coating. The newly formulated photocurable resin can be applied using an ordinary cordless paint sprayer and cured using sunlight in less than a minute, enabling the rapid production of large, load-bearing structures from a small volume of feedstock and low-cost portable equipment. A comprehensive screening process for resin formulations, detailed mechanical compression and tensile analysis of coated polymer structures, and an applied technical demonstration of the technology are described. The photocurable coating described herein greatly strengthens porous polymeric structures using a method that can be easily implemented.

Prophylactic vaccines capable of preventing human papillomavirus (HPV) infections are still inaccessible to a vast majority of the global population due to their high cost and challenges related to multiple administrations performed in a medical setting. In an effort to improve distribution and administration, we have developed dissolvable microneedles loaded with a thermally stable HPV vaccine candidate consisting of Qβ virus-like particles (VLPs) displaying a highly conserved epitope from the L2 protein of HPV (Qβ-HPV). Polymeric microneedle delivery of Qβ-HPV produces similar amounts of anti-HPV16 L2 IgG antibodies compared to traditional subcutaneous injection while delivering a much smaller amount of intradermal dose. However, a dose sparing effect was found. Furthermore, immunization yielded neutralizing antibody responses in a HPV pseudovirus assay. The vaccine candidate was confirmed to be stable at room temperature after storage for several months, potentially mitigating many of the challenges associated with cold-chain distribution. The ease of self-administration and minimal invasiveness of such microneedle patch vaccines may enable wide-scale distribution of the HPV vaccine and lead to higher patient compliance. The Qβ VLP and its delivery technology is a plug-and-play system that could serve as a universal platform with a broad range of applications. Qβ VLPs may be stockpiled for conjugation to a wide range of epitopes, which are then packaged and delivered directly to the patient via noninvasive microneedle patches. Such a system paves the way for rapid distribution and self-administration of vaccines.

Proteinaceous nanoparticles can be used to deliver large payloads of active ingredients, which is advantageous in medicine and agriculture. However, the conjugation of hydrophobic ligands to hydrophilic nanocarriers such as plant viral nanoparticles (plant VNPs) can result in aggregation by reducing overall solubility. Given the benefits of hydrophilic nanocarrier platforms for targeted delivery and multivalent ligand display, coupled with the versatility of hydrophobic drugs, contrast agents, and peptides, this is an issue that must be addressed to realize their full potential. Here, we report two preincubation strategies that use a Pluronic F127 polymer scaffold to prevent the aggregation of conjugated plant VNPs: a plant VNP-polymer precoat (COAT) and an active ingredient formulation combined with a plant VNP-polymer precoat (FORMCOAT). The broad applications of these modified conjugation strategies were highlighted by testing their compatibility with three types of bioconjugation chemistry

The COVID-19 pandemic highlights the need for platform technologies enabling rapid development of vaccines for emerging viral diseases. The current vaccines target the SARS-CoV-2 spike (S) protein and thus far have shown tremendous efficacy. However, the need for cold-chain distribution, a prime-boost administration schedule, and the emergence of variants of concern (VOCs) call for diligence in novel SARS-CoV-2 vaccine approaches. We studied 13 peptide epitopes from SARS-CoV-2 and identified three neutralizing epitopes that are highly conserved among the VOCs. Monovalent and trivalent COVID-19 vaccine candidates were formulated by chemical conjugation of the peptide epitopes to cowpea mosaic virus (CPMV) nanoparticles and virus-like particles (VLPs) derived from bacteriophage Qβ. Efficacy of this approach was validated first using soluble vaccine candidates as solo or trivalent mixtures and subcutaneous prime-boost injection. The high thermal stability of our vaccine candidates allowed for formulation into single-dose injectable slow-release polymer implants, manufactured by melt extrusion, as well as microneedle (MN) patches, obtained through casting into micromolds, for prime-boost self-administration. Immunization of mice yielded high titers of antibodies against the target epitope and S protein, and data confirms that antibodies block receptor binding and neutralize SARS-CoV and SARS-CoV-2 against infection of human cells. We present a nanotechnology vaccine platform that is stable outside the cold-chain and can be formulated into delivery devices enabling single administration or self-administration. CPMV or Qβ VLPs could be stockpiled, and epitopes exchanged to target new mutants or emergent diseases as the need arises.

Protein-polymer conjugates (PPCs) improve therapeutic efficacy of proteins and have been widely used for the treatment of various diseases such as cancer, diabetes, and hepatitis. PEGylation is considered as the "gold standard" in bioconjugation, although in practice its clinical applications are becoming limited because of extensive evidence of immunogenicity induced by pre-existing anti-PEG antibodies in patients. Here, optimized reaction conditions for living aqueous grafting-from ring-opening metathesis polymerization (ROMP) are utilized to synthesize water-soluble polynorbornene (PNB)-based PPCs of lysozyme (Lyz-PPCs) and bacteriophage Qβ (Qβ-PPCs) as PEG alternatives. Lyz-PPCs retain nearly 100% bioactivity and Qβ-PPCs exhibit up to 35% decrease in protein immunogenicity. Qβ-PPCs derived from NB-PEG show no reduction in recognition by anti-PEG antibodies while Qβ-PPCs derived from NB-Zwit show >95% reduction as compared with Qβ-PEG. This work demonstrates a new method for PPC synthesis and the utility of grafting from PPCs to evade immune recognition.

Blood loss causes an estimated 1.9 million deaths per year globally, making new methods to stop bleeding and promote clot formation immediately following injury paramount. The fabrication of functional hemostatic materials has the potential to save countless lives by limiting bleeding and promoting clot formation following an injury. This work describes the melt manufacturing of poly(ε-caprolactone) nanofibers and their chemical functionalization to produce highly scalable materials with enhanced blood clotting properties. The nanofibers are manufactured using a high throughput melt coextrusion method. Once isolated, the nanofibers are functionalized with polymers that promote blood clotting through surface-initiated atom transfer radical polymerization. The functional nanofibers described herein speed up the coagulation cascade and produce more robust blood clots, allowing for the potential use of these functional nonwoven mats as advanced bandages.

Prostate-specific membrane antigen (PSMA) is a membrane-bound protein that is preferentially expressed in the prostate gland and induced in many prostate cancers, making it an important target for new diagnostics and therapeutics. To improve the efficacy of nanoparticle formulations for the imaging and/or eradication of prostate cancer, we synthesized the PSMA-binding glutamic acid derivative DUPA and conjugated it to the external surface of tobacco mosaic virus (TMV) particles. DUPA-targeted TMV was subsequently loaded with the antineoplastic agent mitoxantrone (MTO) or conjugated internally with the fluorescent dye cyanine 5 (Cy5). We found that TMV particles could be efficiently decorated with DUPA and loaded with MTO or Cy5 while maintaining structural integrity. DUPA-targeted TMV particles were able to bind more efficiently to the surface of PSMA+ LNCaP cells compared to non-targeted TMV; but there was little difference in binding efficiency between targeted and untargeted TMV when we tested PSMA− PC3 cells (both cell lines are prostate cancer cell lines). DUPA-targeted TMV particles were internalized by LNCaP cells enabling drug delivery. Finally, we loaded the DUPA-targeted TMV particles and untargeted control particles with MTO to test their cytotoxicity against LNCaP cells in vitro. The cytotoxicity of the TMV-MTO particles (IC50 = 10.2 nM) did not differ significantly from that of soluble MTO at an equivalent dose (IC50 = 12.5 nM) but the targeted particles (TMV-DUPA-MTO) were much more potent (IC50 = 2.80 nM). The threefold increase in cytotoxicity conferred by the DUPA ligand suggests that MTO-loaded, DUPA-coated TMV particles are promising as a therapeutic strategy for PSMA+ prostate cancer and should be advanced to preclinical testing in mouse models of prostate cancer., Prostate-specific membrane antigen (PSMA) is a membrane-bound protein that is preferentially expressed in the prostate gland and induced in many prostate cancers, making it an important target for new diagnostics and therapeutics.

Single dose slow-release vaccines herald a new era in vaccine administration. An ideal device for slow-release vaccine delivery would be minimally invasive and self-administered, making these approaches an attractive alternative for mass vaccination programs, particularly during the time of a pandemic. In this review article, we discuss the latest advances in this field, specifically for prophylactic vaccines able to prevent infectious diseases. Recent studies have found that slow-release vaccines elicit better immune responses and often do not require cold chain transportation and storage, thus drastically reducing the cost, streamlining distribution, and improving efficacy. This promise has attracted significant attention, especially when poor patient compliance of the standard multidose vaccine regimes is considered. Single dose slow-release vaccines are the next generation of vaccine tools that could overcome most of the shortcomings of present vaccination programs and be the next platform technology to combat future pandemics. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Implantable Materials and Surgical Technologies > Nanomaterials and Implants Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Metal–organic framework (MOF)–polymer hybrid materials have been investigated for use in personal protective equipment (PPE) for combating chemical threats. However, few of these composite material...

Bio-based flame retardants (FRs) were employed to successfully reduce the flammability of acrylonitrile–butadiene–styrene (ABS), achieving results comparable to a commercial brominated ABS product ...

Currently, titanium dental implant apposition to bone is achieved via osseointegration leading to ankylosis. A biomimetic Sharpey's fiber-type interface could be constructed around collagen fibrils robustly attached and projecting perpendicularly from the titanium surface. We present a proof-of-concept for a method to create upright-standing collagen nanofibrils covalently bonded to a titanium surface. The method involves activation of the titanium surface using a plasma discharge treatment followed by functionalization with an oxyamine-terminated silane coupling molecule. Using Rapoport's salt, the N-termini of individual type I collagen monomers are converted to ketones. When presented to the functionalized titanium surface, these ketones form oxime linkages with the silanes thus immobilizing the collagen. In a two-step process, these covalently bonded monomers act as sites for the formation of fibrils. Many fibril-surface junctions were observed by scanning electron microscopy on three different surfaces. These findings set the stage for working toward a high surface density of such features which might act as a platform from which to build a synthetic ligament.

In modern manufacturing, it is a widely accepted limitation that the parts patterned by an additive or subtractive manufacturing process (i.e., a lathe, mill, or 3D printer) must be smaller than the machine itself that produced them. Once such parts are manufactured, they can be postprocessed, fastened together, welded, or adhesively bonded to form larger structures. We have developed a foaming prepolymer resin for lithographic additive manufacturing, which can be expanded after printing to produce parts up to 40× larger than their original volume. This allows for the fabrication of structures significantly larger than the build volume of the 3D printer that produced them. Complex geometries comprised of porous foams have implications in technologically demanding fields such as architecture, aerospace, energy, and biomedicine. This manuscript presents a comprehensive screening process for resin formulations, detailed analysis of printing parameters, and observed mechanical properties of the 3D-printed foams.

The development of vaccines against coronaviruses has focused on the spike (S) protein, which is required for the recognition of host-cell receptors and thus elicits neutralizing antibodies. Targeting conserved epitopes on the S protein offers the potential for pan-beta-coronavirus vaccines that could prevent future pandemics. We displayed five B-cell epitopes, originally identified in the convalescent sera from recovered severe acute respiratory syndrome (SARS) patients, on the surface of the cowpea mosaic virus (CPMV) and evaluated these formulations as vaccines. Prime-boost immunization of mice with three of these candidate vaccines, CPMV-988, CPMV-1173, and CPMV-1209, elicited high antibody titers that neutralized the severe acute respiratory syndrome coronavirus (SARS-CoV) in vitro and showed an early Th1-biased profile (2-4 weeks) transitioning to a slightly Th2-biased profile just after the second boost (6 weeks). A pentavalent slow-release implant comprising all five peptides displayed on the CPMV elicited anti-S protein and epitope-specific antibody titers, albeit at a lower magnitude compared to the soluble formulations. While the CPMV remained intact when released from the PLGA implants, processing results in loss of RNA, which acts as an adjuvant. Loss of RNA may be a reason for the lower efficacy of the implants. Finally, although the three epitopes (988, 1173, and 1209) that were found to be neutralizing the SARS-CoV were 100% identical to the SARS-CoV-2, none of the vaccine candidates neutralized the SARS-CoV-2 in vitro suggesting differences in the natural epitope perhaps caused by conformational changes or the presence of N-linked glycans. While a cross-protective vaccine candidate was not developed, a multivalent SARS vaccine was developed. The technology discussed here is a versatile vaccination platform that can be pivoted toward other diseases and applications that are not limited to infectious diseases.

Cardiovascular disease is the number one cause of death globally. Lowering cholesterol levels in plasma is the mainstay therapy; however lifelong treatment and adverse effects call for improved therapeutic interventions. We developed a trivalent vaccine candidate targeting proprotein convertase subtilisin/kexin-9 (PCSK9), apolipoprotein B (ApoB), and cholesteryl ester transfer protein (CETP). Vaccine candidates were developed using bacteriophage Qβ-based virus-like particles (VLPs) displaying antigens of PCKS9, ApoB, and CETP, respectively. Vaccine candidate mixtures were formulated as slow-release PLGA:VLP implants using hot-melt extrusion. The delivery of the trivalent vaccine candidate via the implant produced antibodies against the cholesterol checkpoint proteins at levels comparable to a three-dose injection schedule with soluble mixtures. The reduction in PCSK9 and ApoB levels in plasma, inhibition of CETP (in vitro), and total plasma cholesterol decrease was achieved. All-together, we present a platform technology for a single-dose multi-target vaccination platform targeting cholesterol checkpoint proteins.

Protein–polymer conjugates, typically consisting of one or more polymers covalently attached to a protein, are an increasingly common component in biotechnology. Polymers can increase circulation time, alter immune responses, and influence the self-assembly of proteins to which they are attached. To understand and take full advantage of the benefits that protein–polymer conjugates provide, there is a strong need for structural characterization of both the conjugates and their self-assembled structures. Although X-ray crystallography is suitable for determining protein structure, protein–polymer conjugates do not generally crystallize, requiring the use of alternative techniques. Small-angle scattering, with neutrons in particular, is one such technique. In this article, we review recent work in the area of protein–polymer conjugates and highlight the important role that structure plays. We then highlight shape-dependent and shape-independent approaches for structural characterization of protein–polymer conjugates and future directions in small-angle scattering interpretation. We conclude by introducing a new model that we suggest may be useful in the future to acquire more detailed structural properties.

The standard therapy for cardiovascular disease (CVD) is the administration of statins to reduce plasma cholesterol levels, but this requires lifelong treatment. We developed a CVD vaccine candidate that targets the pro-inflammatory mediator calprotectin by eliciting antibodies against the S100A9 protein. The vaccine, based on bacteriophage Qβ virus-like particles (VLPs) displaying S100A9 peptide epitopes, was formulated as a slow-release PLGA:VLP implant by hot-melt extrusion. The single-dose implant elicited S100A9-specific antibody titers comparable to a three-dose injection schedule with soluble VLPs. In an animal model of CVD (ApoE

Progress in the field of soft devices-i.e., haptics, robotics, and human-machine interfaces (HRHMIs)-has its basis in the science of polymeric materials and chemical synthesis. However, in examining the relevant literature, we find that most developments have been enabled by off-the-shelf materials used either alone or as components of physical blends and composites. In this Progress Report, we take the position that a greater awareness of the capabilities of synthetic chemistry will accelerate the capabilities of HRHMIs. Conversely, an awareness of the applications sought by engineers working in this area may spark the development of new molecular designs and synthetic methodologies by chemists. We highlight several applications of active, stimuli-responsive polymers, which have demonstrated or shown potential use in HRHMIs. These materials share the fact that they are products of state-of-the-art synthetic techniques. The Progress Report is thus organized by the chemistry by which the materials were synthesized, including controlled radical polymerization, metal-mediated cross-coupling polymerization, ring-opening polymerization, various strategies for crosslinking, and hybrid approaches. These methods can afford polymers with multiple properties (i.e. conductivity, stimuli-responsiveness, self-healing and degradable abilities, biocompatibility, adhesiveness, and mechanical robustness) that are of great interest to scientists and engineers concerned with soft devices for human interaction.

With the rapid development of the biopharmaceutical industry, an increasing number of new therapeutic protein products (TPPs) have been approved by the FDA and many others are under pre-clinical and clinical evaluation. A major limitation of biopharmaceuticals is their limited half-life when administered systemically. A one-time, implantable, sustained protein delivery device would be advantageous in order to improve the quality of life of patients. Hot melt extrusion (HME) is a mature technology that has been extensively used for a broad spectrum of applications in the polymer and pharmaceutical industry and has achieved success as evidenced by a variety of FDA-approved commercial products. These commercial products are mostly for sustained delivery of small molecule therapeutics, leaving a significant gap for HME formulation of therapeutic proteins. With the increasing need of sustained TPP delivery, HME shows promise as a downstream processing method due to its high efficiency and economic value. Several challenges remain for the application of HME in protein delivery. Progress of HME for protein delivery, challenges encountered, and potential solutions will be detailed in this review article. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Biology-Inspired Nanomaterials > Protein and Virus-Based Structures.

Human papillomavirus (HPV) is a globally prevalent sexually-transmitted pathogen, responsible for most cases of cervical cancer. HPV vaccination rates remain suboptimal, partly due to the need for multiple doses, leading to a lack of compliance and incomplete protection. To address the drawbacks of current HPV vaccines, we used a scalable manufacturing process to prepare implantable polymer–protein blends for single-administration with sustained delivery. Peptide epitopes from HPV16 capsid protein L2 were conjugated to the virus-like particles derived from bacteriophage Qβ, to enhance their immunogenicity. The HPV-Qβ particles were then encapsulated into poly(lactic-co-glycolic acid) (PLGA) implants, using a benchtop melt-processing system. The implants facilitated the slow and sustained release of HPV-Qβ particles without the loss of nanoparticle integrity, during high temperature melt processing. Mice vaccinated with the implants generated IgG titers comparable to the traditional soluble injections and achieved protection in a pseudovirus neutralization assay. HPV-Qβ implants offer a new vaccination platform, because the melt-processing is so versatile, the technology offers the opportunity for massive upscale into any geometric form factor. Notably, microneedle patches would allow for self-administration in the absence of a healthcare professional, within the developing world. The Qβ technology is highly adaptable, allowing the production of vaccine candidates and their delivery devices for multiple strains or types of viruses.

Antibiotic-loaded poly(methyl methacrylate) (PMMA) cement is commonly used as a local delivery system to treat and prevent orthopedic infections associated with arthroplasties in load-bearing applications. However, these delivery systems are inefficient as release rate sharply declines to subinhibitory levels. Prior studies have shown that by adding in drug-filled cyclodextrin (CD) microparticles into PMMA cement, a more consistent release is observed, and antibiotic refilling through simulated implantation can be achieved. However, the mechanical strengths of PMMA is reduced. In order to decrease the mechanical loss, modified CD microparticles (PMMA-CD) are synthesized that contain covalently appended PMMA chains. The compressive strengths, handling characteristics, and refilling ability of PMMA cement with PMMA-CD are evaluated. Specifically, up to a 13.7% increase in compressive strength is observed when unmodified CD is substituted with PMMA-CD in PMMA samples with 10 wt% CD microparticles. Additionally, a 13.3% increase in working time, a 7.5% decrease in maximum polymerization temperature, and up to a 32.1% increase in amount of drug refilled are observed with the addition of 10 wt% CD PMMA-CD into PMMA in comparison to plain PMMA without CD microparticles.

The COVID-19 pandemic has infected millions of people with no clear signs of abatement owing to the high prevalence, long incubation period and lack of established treatments or vaccines. Vaccines are the most promising solution to mitigate new viral strains. The genome sequence and protein structure of the 2019-novel coronavirus (nCoV or SARS-CoV-2) were made available in record time, allowing the development of inactivated or attenuated viral vaccines along with subunit vaccines for prophylaxis and treatment. Nanotechnology benefits modern vaccine design since nanomaterials are ideal for antigen delivery, as adjuvants, and as mimics of viral structures. In fact, the first vaccine candidate launched into clinical trials is an mRNA vaccine delivered via lipid nanoparticles. To eradicate pandemics, present and future, a successful vaccine platform must enable rapid discovery, scalable manufacturing and global distribution. Here, we review current approaches to COVID-19 vaccine development and highlight the role of nanotechnology and advanced manufacturing.

Cell-based therapies are gaining prominence in treating a wide variety of diseases and using synthetic polymers to manipulate these cells provides an opportunity to impart function that could not be achieved using solely genetic means. Herein, we describe the utility of functional block copolymers synthesized by ring-opening metathesis polymerization (ROMP) that can insert directly into the cell membrane via the incorporation of long alkyl chains into a short polymer block leading to non-covalent, hydrophobic interactions with the lipid bilayer. Furthermore, we demonstrate that these polymers can be imbued with advanced functionalities. A photosensitizer was incorporated into these polymers to enable spatially controlled cell death by the localized generation of (1)O(2) at the cell surface in response to red-light irradiation. In a broader context, we believe our polymer insertion strategy could be used as a general methodology to impart functionality onto cell-surfaces.

Ring opening metathesis polymerization (ROMP) is widely considered an excellent living polymerization technique that proceeds rapidly under ambient conditions and is highly functional group tolerant when performed in organic solvents. However, achieving the same level of success in aqueous media has proved to be challenging, often requiring an organic co-solvent or a very low pH to obtain fast initiation and high monomer conversion. The ability to efficiently conduct ROMP under neutral pH aqueous conditions would mark an important step towards utilizing aqueous ROMP with acid-sensitive functional groups or within a biological setting. Herein we describe our efforts to optimize ROMP in an aqueous environment under neutral pH conditions. Specifically, we found that the presence of excess chloride in solution as well as relatively small changes in pH near physiological conditions have a profound effect on molecular weight control, polymerization rate and overall monomer conversion. Additionally, we have applied our optimized conditions to polymerize a broad scope of water-soluble monomers and used this methodology to produce nanostructures via ring opening metathesis polymerization induced self-assembly (ROMPISA) under neutral pH aqueous conditions.

The COVID-19 pandemic has infected millions of people with no clear signs of abatement owing to the high prevalence, long incubation period and lack of established treatments or vaccines. Vaccines are the most promising solution to mitigate new viral strains. The genome sequence and protein structure of the 2019-novel coronavirus (nCoV or SARS-CoV-2) were made available in record time, allowing the development of inactivated or attenuated viral vaccines along with subunit vaccines for prophylaxis and treatment. Nanotechnology benefits modern vaccine design since nanomaterials are ideal for antigen delivery, as adjuvants, and as mimics of viral structures. In fact, the first vaccine candidate launched into clinical trials is an mRNA vaccine delivered via lipid nanoparticles. To eradicate pandemics, present and future, a successful vaccine platform must enable rapid discovery, scalable manufacturing and global distribution. Here, we review current approaches to COVID-19 vaccine development and highlight the role of nanotechnology and advanced manufacturing.

The broadly neutralizing antibody against HIV-1, b12, binds to the CD4 binding site (CD4bs) on the outer domain (OD) of the gp120 subunit of HIV-1 Env. We have previously reported the design of an E. coli expressed fragment of HIV-1 gp120, b122a, containing about 70% of the b12 epitope with the idea of focusing the immune response to this structure. Since the b122a structure was found to be only partially folded, as assessed by circular dichroism and protease resistance, we attempted to stabilize it by the introduction of additional disulfide bonds. One such mutant, b122a1-b showed increased stability and bound b12 with 30-fold greater affinity as compared to b122a. Various b122a and OD fragment proteins were displayed on the surface of Qβ virus-like particles. Sera raised against these particles in six-month long rabbit immunization studies could neutralize Tier1 viruses across different subtypes with the best results observed with b122a1-b displayed particles. Significantly higher amounts of antibodies directed towards the CD4bs were also elicited by particles displaying b122a1-b. This study highlights the ability of fragment immunogens to focus the antibody response to the conserved CD4bs of HIV-1.

The world is facing a growing crisis of microbial infections, where resistant strains are rapidly outpacing the development of new therapeutics. In an effort to combat this, the polymer community is developing new ways to improve upon drug delivery, synthesizing novel antimicrobial polymers, and using polymer technology to harness combination therapies. This review focuses primarily on the use of polymers to treat both bacterial and fungal infections in recent years. A bevy of work has illustrated that polymer technologies can have a huge impact in treating bacterial infections. However, harnessing polymers to deliver antifungals or as stand-alone therapeutics lags far behind that of interventions for bacterial infections. Fungal infections can be crippling to both human health and the agricultural community, making this area ripe for drug delivery technologies. This review describes recent work and highlights opportunities for bacterial and fungal treatment using soft matter.

Aqueous polymeric systems are critical components for a bevy of uses, most notably in biomedical sciences. However, these materials typically have inherently weak mechanical properties. A critical area of research in recent years is the development of new biocompatible nanofillers to reinforce these polymeric matrices and enhance mechanical properties. In particular, high aspect ratio nanotubes provide the greatest mechanical reinforcement when blended into composite materials. Unfortunately, there are few options for water dispersible nanofillers that would be appropriate for water-soluble polymers. In this study, a plant virus protein nanotube, tobacco mosaic green mild virus (TMGMV), was used to strengthen two hydrophilic composites. In the first example, a cross-linked poly(poly(ethylene glycol) methyl ether acrylate) hydrogel (PPEGMEA) was synthesized with varying amounts of TMGMV. TMGMV was an effective reinforcing agent at low concentrations, increasing the storage and compressive modulus when compared to neat PPEGMEA hydrogels. To further validate the broad applicability of TMGMV reinforcement, polyvinyl alcohol (PVA)/TMGMV composite films were studied. TMGMV was found to have a similar reinforcing effect on these film systems. Rod-shaped viruses may represent a broad based reinforcing agent for aqueous systems in the future.

Hydrogels are an important class of biomaterials, but are inherently weak; to overcome this challenge, we report an in situ manufacturing technique to fabricate mechanically robust, fiber-reinforced poly(ethylene oxide) (PEO) hydrogels. Here, a covalent PEO cross-linking scheme was implemented to derive poly(ε-caprolactone) (PCL) fiber reinforced PEO hydrogels from multilayer coextruded PEO/PCL matrix/fiber composites. By varying PCL fiber loading between ∼0.1 vol % and ∼7.8 vol %, hydrogel stiffness was tailored from 0.69 ± 0.04 MPa to 1.94 ± 0.21 MPa. The influence of PCL chain orientation and enhanced mechanics via uniaxial drawing of PCL/PEO composites revealed a further 225% increase in hydrogel stiffness. To further highlight the robust nature of this manufacturing process, we also derived rigid poly(l-lactic acid) (PLLA) fiber-reinforced PEO hydrogels with a stiffness of 8.71 ± 0.21 MPa. Fibroblast cells were injected into the hydrogel volume, which displayed excellent ingrowth, adhesion, and proliferation throughout the fiber reinforced hydrogels. Finally, the range of mechanical properties obtained with fiber-reinforced hydrogels directed differentiation pathways of MC3T3-E1 cells into osteoblasts. This innovative manufacturing approach to achieve randomly aligned, well-distributed, micrometer-scale fibers within a hydrogel matrix with tunable mechanical properties represents a significant avenue of pursuit not only for load-bearing hydrogel applications, but also targeted cellular differentiation.

Covalent conjugation of water-soluble polymers to proteins is critical for evading immune surveillance in the field of biopharmaceuticals. The most common and long-standing polymer modification is the attachment of methoxypoly(ethylene glycol) (mPEG), termed PEGylation, which has led to several clinically approved pharmaceuticals. Recent data indicate that brush-type polymers significantly enhance in vitro and in vivo properties. Herein, the polymer conformation of poly-(ethylene glycol) is detailed and compared with those of water-soluble polyacrylate and polynorbornene (PNB) when attached to icosahedral virus-like particles. Small-angle neutron scattering reveals vastly different polymer conformations of the multivalent conjugates. Immune recognition of conjugated particles was evaluated versus PEGylated particles, and PNB conjugation demonstrated the most effective shielding from antibody recognition.

Fungi account for billions of infections worldwide. The second most prominent causative agent for fungal infections is Candida albicans (C. albicans). As strains of fungi become resistant to antifungal medications, new treatment modalities must be investigated to combat these infections. One approach is to employ photodynamic therapy (PDT). PDT utilizes a photosensitizer, light, and cellular O2 to produce reactive oxygen species (ROS), which then induce oxidative stress resulting in apoptosis. Silicon phthalocyanine Pc 4 is a photosensitizer that has exhibited success in clinical trials for a myriad of skin diseases. The hydrophobic nature of Pc 4, however, poses significant formulation and delivery challenges in the use of this therapy. To mitigate these concerns, a drug delivery vehicle was synthesized to better formulate Pc 4 into a viable PDT agent for treating fungal infections. Utilizing poly(amidoamine) dendrimers as the framework for the vehicle, ∼13% of the amine chain ends were PEGylated to prom...

Blending thermoplastic polyurethane (TPU) with poly(lactic acid) (PLA) is a proven method to achieve a much more mechanically robust material, whereas the addition of graphene oxide (GO) is increasingly applied in polymer nanocomposites to tailor further their properties. On the other hand, additive manufacturing has high flexibility of structure design which can significantly expand the application of materials in many fields. This study demonstrates the fused deposition modeling (FDM) 3D printing of TPU/PLA/GO nanocomposites and its potential application as biocompatible materials. Nanocomposites are prepared by solvent-based mixing process and extruded into filaments for FDM printing. The addition of GO largely enhanced the mechanical property and thermal stability of the nanocomposites. Interestingly, we found that the mechanical response is highly dependent on printing orientation. Furthermore, the 3D printed nanocomposites exhibit good biocompatibility with NIH3T3 cells, indicating promise as biomaterials scaffold for tissue engineering applications.

As nature's choice in designing complex architectures, the bottom-up assembly of nanoscale building blocks offers unique solutions in achieving more complex and smaller morphologies with wide-ranging applications in medicine, energy, and materials science as compared to top-down manufacturing. In this work, we employ charged tobacco mosaic virus (TMV-wt and TMV-lys) nanoparticles in constructing multilayered fibrous networks via electrostatic layer-by-layer (LbL) deposition. In neutral aqueous media, TMV-wt assumes an anionic surface charge. TMV-wt was paired with a genetically engineered TMV-lys variant that displays a corona of lysine side chains on its solvent-exposed surface. The electrostatic interaction between TMV-wt and TMV-lys nanoparticles became the driving force in the highly controlled buildup of the multilayer TMV constructs. Since the resulting morphology closely resembles the 3-dimensional fibrous network of an extracellular matrix (ECM), the capability of the TMV assemblies to support the adhesion of NIH-3T3 fibroblast cells was investigated, demonstrating potential utility in regenerative medicine. Lastly, the layer-by-layer deposition was extended to release the TMV scaffolds as free-standing biomembranes. To demonstrate potential application in drug delivery or vaccine technology, cargo-functionalized TMV biofilms were programmed.

Uniaxial drawing of melt-coextruded poly(ε-caprolactone) (PCL) microfibers was investigated to understand impact on topological, mechanical, and chemical properties of the fibrous scaffolds. Fibers were uniaxially elongated up to 7-fold to observe polymer chain orientation and crystal structure. Crystallinity and orientation of crystal domains were investigated by DSC and X-ray scattering. Polymer physical properties were directly correlated to bulk fiber properties. Furthermore, the drawn fibers were modified photochemically with functionalized benzophenones. The results of these studies allowed for comparison between fiber dimension/surface area, mechanical properties, and photochemical reaction yield for surface modification. As drawing increased, the modulus and tensile strength of the fibers increased as did the surface area of the scaffolds. By contrast, increased drawing led to a decrease in the ability to undergo photochemical reaction at the polymer surface. This fundamental investigation provides a predictive framework to understand how post-processing impacts three critical parameters for coextruded fibrous biomaterial scaffolds.

Photodynamic therapy (PDT) is an adjuvant, non-invasive cancer treatment that is often limited by the photosensitizer solubility and the availability of oxygen in the tumor environment during treatment. This study describes the use of a water-dispersible fluorous polymer to deliver a small molecule photosensitizer with the goal of overcoming these limitations. Covalent conjugation of the photosensitizer to a fluorous polymer demonstrated enhanced singlet oxygen production, showing the potential to improve the PDT efficacy in hypoxic tumor environments. Cellular uptake and efficiency were evaluated using models for squamous cell carcinoma and melanoma. The high fluorine content of the photosensitizer-conjugated polymer drove self-assembly into micellar nanoparticles that showed uptake into both cancer cell lines, inducing cell death when exposed to broad based white light, but was non-toxic otherwise. Taken together these results demonstrate that the fluorous polymer platform serves as an effective delivery system for small molecule photosensitizers while increasing the generation of toxic reactive oxygen species.

The use of microneedles has facilitated the painless localized delivery of drugs across the skin. However, their efficacy has been limited by slow diffusion of molecules and often requires external triggers. Herein, an autonomous and degradable, active microneedle delivery platform is introduced, employing magnesium microparticles loaded within the microneedle patch, as the built-in engine for deeper and faster intradermal payload delivery. The magnesium particles react with the interstitial fluid, leading to an explosive-like rapid production of H2 bubbles, providing the necessary force to breach dermal barriers and enhance payload delivery. The release kinetics of active microneedles is evaluated in vitro by measuring the amount of IgG antibody (as a model drug) that passed through phantom tissue and a pigskin barrier. In vivo experiments using a B16F10 mouse melanoma model demonstrate that the active delivery of anti-CTLA-4 (a checkpoint inhibitor drug) results in greatly enhanced immune response and significantly longer survival. Moreover, spatially resolved zones of active and passive microneedles allow a combinatorial rapid burst response along with slow, sustained release, respectively. Such versatile and effective autonomous dynamic microneedle delivery technology offers considerable promise for a wide range of therapeutic applications, toward a greatly enhanced outcome, convenience, and cost.

Plant virus nanoparticles are recognized as a platform technology for potential applications in nanomedicine. While non-infectious toward mammals, many plant virus nanoparticles are recognized by the immune system and act as potent adjuvants, both in the classical setting of vaccination and cancer immunotherapy. In the context of cancer immunotherapy, we have demonstrated potent efficacy of plant virus, particularly cowpea mosaic virus (CPMV) when applied intratumorally; CPMV signals through and activates multiple toll-like receptors, which primes a potent innate immune activation leading to reprogramming of the tumor microenvironment from an immunosuppressed to immune-activated state. Data in mouse models of melanoma, colon cancer, ovarian cancer, glioma, and breast cancer demonstrate potent efficacy through priming of the innate immune system leading to adaptive and systemic anti-tumor immunity and most importantly immune memory. Efficacy was also replicated in canine patients with melanoma. Given the promise of the plant virus nanotechnology as an adjuvant for cancer immunotherapy, we also have begun to utilize the technology as a vaccination platform for the generation of COVID-19 vaccine candidates. We formulated multivalent COVID-19 vaccine candidates using plant virus nanoparticles displaying SARS-CoV-2 S protein peptide B cell epitopes. The plant virus nanoparticle confers efficient lymphatic trafficking and targeting of antigen-presenting cells; the adjuvant properties of the nanotechnology lead to robust antibody levels against the target, S protein. While other vaccine candidates have advanced through clinical testing, our approach has unique advantages: The high thermal and pH stability of the plant virus nanotechnology alleviates cold chain requirements; further, the stability of the platform technology enables its integration into vaccine delivery devices such as microneedle patches that can be shipped globally and be self-administered. In this presentation, we will discuss our data on the cancer immunotherapy and highlight the potential to pivot the technology for infectious disease vaccines with unique attributes. This work was funded in part through grants from the National Cancer Institute (U01CA218292) and National Science Foundation (RAPID CMMI-2027668). Citation Format: Nicole F. Steinmetz, Jonathan K. Pokorski, Steven N. Fiering, P. Jack Hoopes, Sourabh Shukla, Oscar A. Ortega-Rivera, Steven King, Cyril J. Empig. Plant viral nanoparticle-based adjuvants for cancer immunotherapy and COVID-19 vaccines [abstract]. In: Proceedings of the AACR Virtual Meeting: COVID-19 and Cancer; 2021 Feb 3-5. Philadelphia (PA): AACR; Clin Cancer Res 2021;27(6_Suppl):Abstract nr S05-02.

Deoxyribonucleic acid (DNA) was investigated as a flame retardant (FR) additive for melt-compounded formulations with low-density polyethylene (LDPE) and compared to LDPE compounded with melamine polyphosphate (MPP), one of the industry standard intumescent FR additives for plastics. DNA showed a much greater compatibility with the LDPE matrix than MPP. At high loading levels, DNA showed minimal increases in compounding torque, while MPP increased torque by over 20%. Qualitative evaluation using SEM and EDS showed that DNA/LDPE blends had significantly improved cross-sectional morphology, with fewer microaggregates and improved particle dispersion than MPP/LDPE. Horizontal burn testing showed that DNA markedly reduced flame burn distances in LDPE above loading levels of 5% w/w. Biochemical characterization of heat-treated DNA revealed that DNA undergoes denaturation, fragmentation, and oxidation during compounding, but these processes did not appear to have an effect on its FR properties. This study expands the field of DNA-based FR beyond specialty substrates, and establishes DNA as a viable green FR additive for commodity polymer applications.

Nanoparticle-based technologies, including platforms derived from plant viruses, hold great promise for targeting and delivering cancer therapeutics to solid tumors by overcoming dose-limiting toxicities associated with chemotherapies. A growing body of data indicates advantageous margination and penetration properties of high aspect-ratio nanoparticles, which enhance payload delivery, resulting in increased efficacy. Our lab has demonstrated that elongated rod-shaped and filamentous macromolecular nucleoprotein assemblies from plant viruses have higher tissue diffusion rates than spherical particles. In this study, we developed a mathematical model to quantify diffusion and uptake of tobacco mosaic virus (TMV) in a spheroid system approximating a capillary-free segment of a solid tumor. Model simulations predict TMV concentration distribution with time in a tumor spheroid for different sizes and cell densities. From simulations of TMV concentration distribution, we can quantify the effect of TMV aspect ratio (e.g., nanorod length-to-width) with and without cellular uptake by modulated surface chemistry. This theoretical analysis can be applied to other viral or nonviral delivery systems to complement the experimental development of the next generation of nanotherapeutics.

Polymeric fibrous constructs possess high surface area-to-volume ratios when compared with solid substrates and are quite commonly used as tissue engineering and cell growth scaffolds. An overview of important design and material considerations for fibrous scaffolds as well as an outline of both established and emerging solution- and melt-based fabrication techniques is provided. Innovative post-process surface modification avenues using "click" chemistry with both single and dual active cues as well as gradient cues, which maintain the fibrous structure are described. By combining process parameters with post-process surface modification, researchers have been able to selectively tune cellular response after seeding and culturing on fibrous constructs.