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Natural biopolymer nanoparticles (NPs), including nanocrystalline cellulose (CNC) and lignin, have shown potential as scaffolds for targeted drug delivery systems due to their wide availability, cost‐efficient preparation, and anticipated biocompatibility. Since both CNC and lignin can potentially cause complications in cell viability assays due to their ability to scatter the emitted light and absorb the assay reagents, we investigated the response of bioluminescent (CellTiter‐Glo®), colorimetric (MTT® and AlamarBlue®) and fluorometric (LIVE/DEAD®) assays for the determination of the biocompatibility of the multimodal CNC and lignin constructs in murine RAW 264.7 macrophages and 4T1 breast adenocarcinoma cell lines. Here, we have developed multimodal CNC and lignin NPs harboring the radiometal chelator DOTA (1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid) and the fluorescent dye Cyanine 5 for the investigation of nanomaterial biodistribution in vivo with nuclear and optical imaging, which were then used as the model CNC and lignin nanosystems in the cell viability assay comparison. CellTiter‐Glo® based on the detection of ATP‐dependent luminescence in viable cells revealed to be the best assay for both nanoconstructs for its robust linear response to increasing NP concentration and lack of interference from either of the NP types. Both multimodal CNC and lignin NPs displayed low cytotoxicity and favorable interactions with the cell lines, suggesting that they are good candidates for nanosystem development for targeted drug delivery in breast cancer and for theranostic applications. Our results provide useful guidance for cell viability assay compatibility for CNC and lignin NPs and facilitate the future translation of the materials for in vivo applications.

In this study, tall oil fatty acid ester of softwood kraft lignin (TOFA-L) was used to prepare TOFA lignin nanoparticles (TLNP) in water. The average diameters for two prepared TLNPs in 0.1 mg/ml concentration were 140 nm and 160 nm. TLNPs were attached covalently onto modified and unmodified cellulose fibres to form an antimicrobial composite material. The modified cellulose fibres contained reactive allylic double bonds with a degree of substitution of 0.05. The antimicrobial properties of both TLNPs and TLNP coated fibres (TLNP-C) were studied against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa using silver nanospheres (average size 10 nm) and Lignoboost lignin particles with 300 and 400 nm sizes as references. Antimicrobial activity of the samples was stronger against Gram-positive S. aureus cells than against Gram-negative target microbes E. coli and P. aeruginosa.

Biorenewable polymers have emerged as an attractive alternative to conventional metallic and organic materials for a variety of different applications. This is mainly because of their biocompatibility, biodegradability and low cost of production. Lignocellulosic biomass is the most promising renewable carbon-containing source on Earth. Depending on the origin and species of the biomass, lignin consists of 20–35% of the lignocellulosic biomass. After it has been extracted, lignin can be modified through diverse chemical reactions. There are different categories of chemical modifications, such as lignin depolymerization or fragmentation, modification by synthesizing new chemically active sites, chemical modification of the hydroxyl groups, and the production of lignin graft copolymers. Lignin can be used for different industrial and biomedical applications, including biofuels, chemicals and polymers, and the development of nanomaterials for drug delivery but these uses depend on the source, chemical modifications and physicochemical properties. We provide an overview on the composition and properties, extraction methods and chemical modifications of lignin in this review. Furthermore, we describe different preparation methods for lignin-based nanomaterials with antioxidant UV-absorbing and antimicrobial properties that can be used as reinforcing agents in nanocomposites, in drug delivery and gene delivery vehicles for biomedical applications.

Cross-linked and decolorized lignin nanoparticles (LNPs) were prepared enzymatically and chemically from softwood Kraft lignin. Colloidal lignin particles (CLPs, ca. 200 nm) in a non-malodorous aqueous dispersion could be dried and redispersed in tetrahydrofuran (THF) or in water retaining their stability i.e. spherical shape and size. Two fungal laccases, Trametes hirsuta (ThL) and Melanocarpus albomyces (MaL) were used in the cross-linking reactions. Reactivity of ThL and MaL on Lignoboost™ lignin and LNPs was confirmed by high performance size exclusion chromatography (HPSEC) and oxygen consumption measurements with simultaneous detection of red-brown color due to the formation of quinones. Zeta potential measurements verified oxidation of LNPs via formation of surface-oriented carboxylic acid groups. Dynamic light scattering (DLS) revealed minor changes in the particle size distributions of LNPs after laccase catalyzed radicalization, indicating preferably covalent intraparticular cross-linking over polymerization. Changes in the surface morphology of laccase treated LNPs were imaged by atomic force (AFM) and transmission emission (TEM) microscopy. Furthermore, decolorization of LNPs without degradation was obtained using ultrasonication with H2O2 in alkaline reaction conditions. The research results have high impact for the utilization of Kraft lignin as nanosized colloidal particles in advanced bionanomaterial applications in medicine, foods and cosmetics including different sectors from chemical industry.

Lignin, an aromatic biopolymer, is the main by-product of pulp manufacture, and has been under intense study, as it offers great promise as an alternative for petrochemical polymers. However due to its heterogeneity, the applications where lignin can be used have been limited, leading to the vast majority of it being burned for fuel. Colloidal lignin particles (CLPs) offer a means to disperse lignin homogenously into both water and other media, such as polymers. However, no means thus far have been presented that would allow for a large-scale production of CLPs. Herein we show an industrially scalable closed cycle process of CLP production. In the process, a concentrated solution of lignin in tetrahydrofuran (THF) and ethanol (EtOH) is added into the non-solvent water, instantaneously forming CLPs through self-assembly. The organic solvents are recovered and reused in the process. The aqueous CLPs are concentrated by ultrafiltration and the concentrated particles are spray dried, leading to redispersible microclusters. CLPs can be used in multiple applications, such as Pickering emulsions and composite materials. A significant portion of the 50 million tons of lignin produced by the pulp industry could be made into CLPs with this low cost process, which would open a whole new class of materials for industrial applications.

Fundamentals of nanoprecipitation process to form colloidal lignin particles (CLPs) from tetrahydrofuran (THF)-water solvent system were studied, and applied in establishment of a robust reactor design for scaled-up CLP production. Spherical lignin particles with an average diameter of 220 nm could be produced by the new reactor design. Evaporation was applied for removal of THF, concentration of the CLP dispersions, and finally for drying of the CLPs into flake like dry form. The dried CLPs could be re-dispersed in water to restore their colloidal form by applying short physical agitation. Salt triggered sedimentation of the particles was also investigated as a way for reducing the energy consumption related to water evaporation from the CLP dispersions. Aqueous thermal post-treatments were demonstrated to yield structural reinforcement of the CLP structure against solvation in various lignin solvents. In summary, the presented work pushes forward the conceptual design of large-scale CLP production, and addresses some of the foreseen technical challenges.

Currently, nanosystems have been developed and applied as promising vehicles for different biomedical applications. We have developed three lignin nanoparticles (LNPs): pure lignin nanoparticles (pLNPs), iron(III)-complexed lignin nanoparticles (Fe-LNPs), and Fe3O4-infused lignin nanoparticles (Fe3O4-LNPs) with round shape, narrow size distribution, reduced polydispersity and good stability at pH 7.4. The LNPs showed low cytotoxicity in all the tested cell lines and hemolytic rates below 12% after 12 h of incubation. Additionally, they induced hydrogen peroxide production in a small extent and time-dependent manner, and the interaction with the cells increased over time, exhibiting a dose-dependent cell uptake. Concerning the drug loading, pLNPs showed the capacity to efficiently load poorly water-soluble drugs and other cytotoxic agents, e.g. sorafenib and benzazulene (BZL), and improve their release profiles at pH 5.5 and 7.4 in a sustained manner. Furthermore, the BZL-pLNPs presented an enhanced antiproliferation effect in different cells compared to the pure BZL and showed a maximal inhibitory concentration ranging from 0.64 to 12.4 μM after 24 h incubation. Overall, LNPs are promising candidates for drug delivery applications, and the superparamagnetic behavior of Fe3O4-LNPs makes them promising for cancer therapy and diagnosis, such as magnetic targeting and magnetic resonance imaging.

The surface modification of nanoparticles (NPs) using different ligands is a common strategy to increase NP−cell interactions. Here, dentin phosphophoryn‐derived peptide (DSS) lignin nanoparticles (LNPs) are prepared and characterized, the cellular internalization of the DSS‐functionalized LNPs (LNPs‐DSS) into three different cancer cell lines is evaluated, and their efficacy with the widely used iRGD peptide is compared. It is shown that controlled extent of carboxylation of lignin improves the stability at physiological conditions of LNPs formed upon solvent exchange. Functionalization with DSS and iRGD peptides maintains the spherical morphology and moderate polydispersity of LNPs. The LNPs exhibit good cytocompatibility when cultured with PC3‐MM2, MDA‐MB‐231, and A549 in the conventional 2D model and in the 3D cell spheroid morphology. Importantly, the 3D cell models reveal augmented internalization of peptide‐functionalized LNPs and improve antiproliferative effects when the LNPs are loaded with a cytotoxic compound. Overall, LNPs‐DSS show equal or even superior cellular internalization than the LNPs‐iRGD, suggesting that DSS can also be used to enhance the cellular uptake of NPs into different types of cells, and release different cargos intracellularly.

Tässä on AKAa muttei meidän projekti koodeja, tai vielä systeemissä niitä. Cellulose nanocrystals (CNCs) have remarkable potential to improve the delivery of diagnostic and therapeutic agents to tumors; however, the in vivo studies on CNC biodistribution are still limited. We developed CNC-based imaging probes for the in vitro and in vivo evaluation using two labeling strategies: site-specific hydrazone linkage to the terminal aldehyde of the CNC and nonsite-specific activation using 1,1′-carbonyldiimidazole (CDI). The in vivo behavior of unmodified CNC, DOTA-CNC (ald.), and DOTA-CNC (OH) was investigated in healthy and 4T1 breast cancer mouse models. They displayed good biocompatibility in cell models. Moreover, the biodistribution profile and SPECT/CT imaging confirmed that the accumulation of 111 In-labeled DOTA-CNC (ald.) and 111 In-DOTA-CNC (OH) was primarily in hepatic, splenic, and pulmonary ducts in accordance with the clearance of nontargeted nanoparticles. The developed CNC imaging probes can be used to obtain information with noninvasive imaging on the behavior in vivo to guide structural optimization for targeted delivery.

Acid-precipitated lignin nanoparticles with a cationic polymer coating exhibit antibacterial activity when infused with silver. While the use of such particles would be beneficial due to their high antibacterial activity with a low silver content, their production holds steps that are difficult to scale up to inexpensive industrial manufacture. For example, the production of acid-precipitated lignin nanoparticles requires the use of ethylene glycol, which is not easily recycled. Furthermore, the binding of silver to these particles is weak, and thus the particles need to be used rapidly after preparation. Here, we show that with a deprotonation reaction of an organic solution of anhydrous lignin and subsequent ion exchange with silver nitrate and colloid formation by solvent exchange, highly spherical silver carboxylate colloidal lignin particles (AgCLPs) can be prepared. Silver is not released from the particles in deionized water but can be released in physiological conditions, shown by their high antibacterial efficacy with low silver loading. In comparison to lignin nanoparticles with weakly bound silver, AgCLPs have high antibacterial activity even without cationic polyelectrolyte coating, and they retain their antibacterial activity for days. While the rapid depletion of silver from silver-infused lignin nanoparticles can be considered beneficial for some applications, the sustained antibacterial activity of the AgCLPs with ionically bound silver will enable their use in applications where silver nanoparticles have been previously used. Our results demonstrate that CLPs, which can be produced with a closed cycle process on a large scale, can be rapidly and quantitatively functionalized into active materials.

Slow-release fertilizers represent a possible large-scale application for plant polymers. Here we show a facile way to stabilize urea in fertilizer systems by lignin. Chelation of kraft black liquor with calcium acetate at pH 13 precipitated lignin as a calcium complex (Ca-lignin), which offered beneficial effects if compared to those from lignin obtained by precipitation at low pH (Acid-lignin). The reduced affinity of water to Ca-lignin was exploited in the formulation of slow release fertilizers comprising wheat straw sections impregnated with Ca-lignin in molten urea. Compared to the case of Acid-lignin, immersion in water was slowed down more extensively by Ca-lignin. After 24 h incubation at low moisture conditions, the highest proportion of urea retained in the Ca-lignin/straw fertilizer system was 58%. The water resistance of Ca-lignin was explained by a lower aqueous solubility that differed from the typical pH-dependent solubility of Acid-lignin. Electron microscopy, infrared spectroscopy, and accessible surface areas suggested that Ca-lignin consisted of less densely packed molecules organized as calcium-chelated chains. Overall, the controlled water-solubility of lignin precipitated by metal cations is greatly beneficial in fertilizer systems and can open new opportunities in material development (permeable films and others).

The magnetic nature of iron-containing nanoparticles enables multiple high-end applications. Metal alkoxides are a highly reactive chemical species, which are widely used in ceramics and sol–gel manufacture. However, their use with organic molecules has been mostly limited to catalytic purposes due to their highly reactive nature. Lignin is the second most abundant biopolymer in the world-rich in OH groups and amenable to highly stable colloid nanoparticle formation by a simple solvent exchange process. Here we show that the reaction between iron isopropoxide and lignin in tetrahydrofuran (THF) solution produces metal–organic nanoparticles with tunable morphologies, ranging from hollow and solid nanospheres to open network structures. The immediate condensation reaction between lignin and iron isopropoxide as well as the resulting structure morphology can be controlled by varying the reaction parameters. Despite iron isopropoxide being highly water sensitive, the formed structures are stable as water suspensions. Our results demonstrate that solution processable metal–organic nanoparticles can be easily produced with macromolecular polyols in an inert solvent, such as THF. This presents a facile method of obtaining various metal–organic nanomaterials, with a wide range of metal alkoxides and organic polyols to choose from. We anticipate that metal–bioorganic sol–gel reactions will produce biocompatible materials with enhanced functionality, such as magnetic, antibacterial and catalytic properties depending on the chosen metal and polyol.

A scalable tubular flow reactor was designed and developed for the continuous formation of colloidal lignin particles (CLPs). The reactor consists of a series of tubes, inside which many static mixing elements are equipped to aid in the formation of a homogeneous dispersion of CLPs. The colloids were formed instantaneously through self-assembly upon the addition of the lignin solution into water. The effects of flowrate, length of the tubes and static mixing elements on the particle size, stability and CLP yield after drying were determined. It was found that a higher flowrate of lignin solution within the testing range of 32-240 mL/min resulted in smaller sized CLPs. Optimizations of the mixing length and the static mixing elements to 3 m and at least 1 m, respectively, could ensure an efficient mixing, thus resulting in CLP dispersions with smaller size of lignin particles (200 nm – 400 nm) and high lignin concentrations (up to 2.8 wt. %) along with yields up to 95 %. The TEM images indicated that the formed colloids are composed of lignin particles of regular sphere shape and with good stability. The tubular reactor offers better control of particle size which ensures the formation of colloidal dispersions with narrower particle size distribution in comparison to a stirred mixer reactor. Furthermore, using a tubular reactor enables the continuous production of CLPs, making it suitable for scale up and industrial applications.

The purpose of this study is to investigate the techno-economic feasibility of an environmentally sustainable and green process for the cost-effective large-scale manufacturing of colloidal lignin particles. The process involves the instantaneous formation of colloidal lignin particles (CLPs) through self-assembly when a concentrated solution of lignin in tetrahydrofuran (THF) and ethanol is introduced into water. The capacity of the plant is assumed to be 50 kt per year of dry colloidal lignin and Aspen plus simulation program is used for the mass and energy balance calculations. The process equipment design and pricing are carried out based on relevant literature and vendor data. Results show that the total investment cost for a plant integrated with an existing pulp mill or bio-refinery is 36 M€ and the annual operating cost is 46 M€. The project lifetime is assumed as 20 years and the cost of production of colloidal lignin is found to be 0.99 € kg−1 (in case of integration) and 1.59 € kg−1 (without integration). The revenue for the process comes mainly from selling the colloidal lignin particles and additional revenue is generated from high pressure and low-pressure steam condensate sold as district heat. The payback period with a CLP selling price of 1.10 € kg−1 is found to be roughly 5 years. A minimum profitability requirement of 10% is considered for the techno-economic analysis and the internal rate of return (IRR) is calculated as 17% making the process viable and profitable. In addition, a sensitivity analysis is carried out to evaluate the effect of raw material price and ethanol recovery on the operating cost. Colloidal lignin has the potential to compete favorably as a renewable replacement for petroleum based feedstock like polyethylene, polypropylene, polyethylene terephthalate (PET) and phenol and can be used in attractive applications like phenol formaldehyde (PF) resins, foams, carbon fillers, bactericides and composites.

Aim: To carboxylate kraft lignin toward the functionalization of carboxylated lignin nanoparticles (CLNPs) with a block copolymer made of PEG, poly(histidine) and a cell-penetrating peptide and then evaluate the chemotherapeutic potential of the innovative nanoparticles. Materials & methods: The produced nanoparticles were characterized and evaluated in vitro for stability and biocompatibility and the drug release profiles and antiproliferative effect were also assessed. Results: The prepared CLNPs showed spherical shape and good size distribution, good stability in physiological media and low cytotoxicity in all the tested cell lines. A poorly water-soluble cytotoxic agent was successfully loaded into the CLNPs, improving its release profiles in a pH-sensitive manner and showing an enhanced antiproliferative effect in the different cancer cells compared with a normal endothelial cell line. Conclusion: The resulting CLNPs are promising candidates for anticancer therapy.

openaire: EC/H2020/720303/EU//ZELCOR Coating of colloidal lignin particles (CLPs), or lignin nanoparticles (LNPs), with proteins was evaluated in order to establish a safe, self-assembly mediated modification technique to tune their surface chemistry. Gelatin and poly- l-lysine formed the most pronounced protein corona on the CLP surface, as determined by dynamic light scattering (DLS) and zeta potential measurements. Spherical morphology of individual protein coated CLPs was confirmed by transmission electron (TEM) and atomic force (AFM) microscopy. A mechanistic adsorption study with several random coiled and globular model proteins was carried out using quartz crystal microbalance with dissipation monitoring (QCM-D). The three-dimensional (3D) protein fold structure and certain amino acid interactions were decisive for the protein adsorption on the lignin surface. The main driving forces for protein adsorption were electrostatic, hydrophobic, and van der Waals interactions, and hydrogen bonding. The relative contributions of these interactions were highly dependent on the ionic strength of the surrounding medium. Capillary electrophoresis (CE) and Fourier transform infrared spectroscopy (FTIR) provided further evidence of the adsorption-enhancing role of specific amino acid residues such as serine and proline. These results have high impact on the utilization of lignin as colloidal particles in biomedicine and biodegradable materials, as the protein corona enables tailoring of the CLP surface chemistry for intended applications.

A lack of renewable resources and their inefficient use is a major challenge facing the society. Lignin is a natural biopolymer obtained mainly as a by-product from the pulp- and paper-making industries, and is primarily burned to produce energy. However, interest for using lignin in more advanced applications has increased rapidly. In particular, lignin based nanoparticles could find potential use in functional surface coatings, nanoglue, drug delivery, and microfluidic devices. In this work, a straightforward method to produce lignin nanoparticles from waste lignin obtained from kraft pulping is introduced. Spherical lignin nanoparticles were obtained by dissolving softwood kraft lignin in tetrahydrofuran (THF) and subsequently introducing water into the system through dialysis. No chemical modification of lignin was needed. Water acts as a non-solvent reducing lignin's degrees of freedom causing the segregation of hydrophobic regions to compartments within the forming nanoparticles. The final size of the nanoparticles depended on the pre-dialysis concentration of dissolved lignin. The stability of the nanoparticle dispersion as a function of time, salt concentration and pH was studied. In pure water and at room temperature the lignin nanoparticle dispersion was stable for over two months, but a very low pH or high salt concentration induced aggregation. It was further demonstrated that the surface charge of the particles could be reversed and stable cationic lignin nanoparticles were produced by adsorption of poly(diallyldimethylammonium chloride) (PDADMAC).

Liquid phthalocyanine and fullerene derivative monomers were synthesized, which can be cationically polymerized either thermally or by light and are suitable for preparing complex solar cell structures, obtainable only by organic vacuum deposition till now. A sandwich solar cell with a bulk heterojunction layer between single layers was shown to produce higher currents and voltages than either pure bilayer or pure bulk heterojunction. The proposed in situ polymerization method can be applied to a variety of active layers for preparation of solution-processed solar cells.

By using an advanced polarization modulation infrared reflection adsorption spectroscopy (PM-IRRAS) device it is possible to study the photopolymerization of an ultrathin layer of a porphyrin monomer in real time. The method can be compared with the indirect UV/Vis method previously introduced by our group. With PM-IRRAS it is possible to analyze polymerization kinetics of photopolymerization at various temperatures to determine the activation energy of the reaction.

Cationic photopolvmerization is a convenient in situ polvmerization method for organic thin film preparation. In this work, the polymerization mechanisms is applied for highly viscous cross-linking monomers, using tetra-alkylepoxyporphyrin (TAEP) as a case study. By comparing the UV-Vis spectra of the polymerized sample before and after the unreacted monomers have been dissolved, it is possible to estimate the polymerization yield. An IR spectrum of a reference thick film confirms full polymerization. Scanning fluorescence lifetime microscopy and AFM show the uniformity of the polymer. It was shown that photopolymerization is highly dependent on the substrate nature and requires at best case a 10 min illumination at 90 °C. Thermal polymerization of the same sample requires 10 min heating at 150 °C in dark. It was also shown that TAEP works as a self-sensitizer for cationic photopolymerization. The proposed method is a mild and versatile technique for in situ preparation of thin polymeric films directly from chromophore monomers.

We describe the synthesis and cationic photopolymerization of a C 60 de-rivative bearing a 2,4,6-tris(epoxynonyloxy)phenyl moiety (FB9ox). Rheological analy-sis of monomer indicates that temperature of 130 8C yields sufficiently low viscosityfor polymerization. A thin film of the liquid monomer has been cationically photopoly-merized with a photoinitiator system of curcumin and p-(octyloxyphenyl)phenyliodo-nium hexafluoroantimonate, which harvests 424 nm light instead of commonly usedultraviolet light. The degree of polymerization was determined with ATR-IR. Thereaction is the first recorded photopolymerization of a fullerene derivative thin film.The polymer exhibits good mechanical and chemical stabilities. The polymerizationcan also be achieved by annealing at 150 8C without illumination, but with a smallerdegree of polymerization. VV C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46:5194–5201, 2008 Keywords: cationic; cationic polymerization; conducting polymer; crosslinking; cur-cumin; epoxy; films; fullerene; iodoniumonium salt; liquid; OMAN071; oxirane; photo-polymerization; rheology; synthesis; thin film; viscosity

By using an advanced polarization modulation infrared reflection adsorption spectroscopy (PM-IRRAS) device it is possible to study the photopolymerization of an ultrathin layer of a porphyrin monomer in real time. The method can be compared with the indirect UV/Vis method previously introduced by our group. With PM-IRRAS it is possible to analyze polymerization kinetics of photopolymerization at various temperatures to determine the activation energy of the reaction.

Method of forming colloidal lignin particles, comprising the step of dissolving lignin in a mixture of organic solvents, feeding of the said solution into water, and forming a colloidal dispersion of lignin. The used solvents are recovered with methods such as distillation and reused in the process. Water is removed from the colloidal dispersion by ultrafiltration and reused in the process. The concentrated colloidal dispersion is dried by spray drying. The invention can be used in applications where the colloidal nature of lignin will afford an advantage over bulk lignin.