Our research is focused on the synthesis, characterization and applications of novel bio-based functional materials. One main scientific goal  for the group is understanding and explaining the correlation between the processes, surface characteristics and morphologies of the nanoparticles,  material properties and  material performance. More information is described as follows:

Nanocellulose and nanochitin processing

Mathew AP, Oksman K., Karim Z., Liu P., Khan SA, Naseri N., Process scale up and characterization of wood cellulose nanocrystals hydrolysed using bioethanol pilot plant.  (2014) Industrial Crops and Products, 58 ,  212-219.

 

Mtibe A., Linganiso L., Mathew AP, Oksman K., John M, Ananjiwala RD,

A comparative study on the properties and micro and nanopapers produced from cellulose and cellulose nanofibers, Carbohy. Polym,118. (2015) 1.

We focus on the development and optimization of efficient processing methods for isolation of nanoreinforcements from biomass and bioresidues. Eg, isolation strategies for nanocrystals and nanofibers based on cellulose, chitin and collagen were developed successfully. Wood resources/residues, bamboo, natural fibers, sugar cane bagasse, Prosopis juliflora(mesquite) crab shell residue, etc. We also work with surface  modifications (anionic, cationic, zwitter ionic, polymer grafts, phosphorylated, cationic) etc. with an aim to enhance fibrillation and/or add functionality to the nanomaterial..

Characterisation of surface interactions and adsorption  of nanoparticles

Liu P, Borrell P, Božič M, Kokol V, Oksman K, Mathew AP,  Nanocelluloses and their phosphorylated derivatives for selective adsorption of Ag+, Cu2+ and Fe3+ from water, J. Hazar. Mater 294, 2015 177-185..

Liu P., Oksman K ,. Mathew AP. Surface adsorption and self-assembly of Cu(II) ions on TEMPO-oxidized cellulose nanofibers in aqueous media J Colloid Interfac .  J Coll. Inter  Sci. 464C (2016) 175-182

In recent years, nanocelluloses functioning as nanobioadsorbents have garnered considerable attention for the remediation of heavy metal ions due to their advantages of both facilitating biosorption and being nanosized. In addition, the inherent fibrous nature and easily functionalizable surface of nanocellulose, coupled with its hydrophilic properties, low cost, excellent mechanical properties, nontoxicity and sustainable source, provide a huge potential for its use as a functional component of water filters or filtration membranes. We previously reported that the sorption capacities of Ag+, Cu2+ and Fe3+ onto native cellulose nanocrystals are higher than those of cellulose nanofibers (56 mg/g, 19 mg/g and 6 mg/g, respectively). Inclusion of metal-binding groups, such as carboxylate, phosphate and amine groups, onto the surface of cellulose nanofibers for biosorption can increase the metal removal capacity remarkably. We study the adsorption capacity, adsorption mechanisms, and  self assembly on adsorbed entities on nanocellulose and its hybrids.

Electrospinning of biobased nano composites and hybrids

Goetz LA, Naseri N, Nair SS, Karim Z, Mathew AP. All cellulose electrospun water purification membranes nanotextured using cellulose nanocrystals. Cellulose (London). 2018;25(5):3011–23.

 

Goetz LA, Jalvo B, Garcia RR. Mathew AP, Superhydrophilic anti-fouling electrospun cellulose acetate membranes coated with chitin nanocrystals for water filtration J Memb Sci 2016, 238-248.

Electrospinning is the most popular technology for fabrication of fibers in micron to nano scale due to its simplicity cost effectiveness, flexibility, scale-up potential. It is well established that cellulose nanocrystals with different surface groups as hydroxyl, sulphonic or carboxyl groups can be obtained depending on the isolation route used. Our recent research successfully prepared reinforced electrospun fibers with 50 wt% nanocrystals and showed that the spinnability and fiber characteristics were affected significantly by the surface characteristics of the used nanocrystals. Electrospinning using cellulose nanocrystal based fibers provide several potential advantages including i) reinforcing effect  for electrospun fibers which are inherently weak ii) orientation of nanocrystals under the influence of electric field iii) self assembling of nanocrystals under the influence of electric field iv) introduction of functional properties for the fibers and the fiber mats depending on the surface characteristics of the used nanocrystals. Nanocellulose coated electrospun polymers was highly promising as water purification membranes. The use of electrospun nanocomposites in medical application was also developed.

Biobased membranes/filters for water purification

Chuantao Zhu, Peng Liu, and Aji P. Mathew, Self-Assembled TEMPO Cellulose Nanofibers: Graphene Oxide-Based Biohybrids for Water Purification

ACS Applied Materials & Interfaces 2017 9 (24), 21048-21058

DOI: 10.1021/acsami.7b06358

Karim Z, Claudpierre S., Grahn M, Oksman K,. Mathew A. P., Nanocellulose based functional membranes for water cleaning: Tailoring of mechanical properties, porosity and metal ion capture. Journal of Membrane Science (2016) 514, 418 – 428.

 

Z Karim, Z.; Hakalahti, M.; Tammelin, T.; Mathew, A. P. In Situ TEMPO Surface Functionalization of Nanocellulose Membranes for Enhanced Adsorption of Metal Ions from Aqueous Medium. RSC Adv. 2017, 7, 5232-5241

On this topic we focus on surface characteristics of nanocellulose and nanochitin nanocrystals and understand their potential in membranes/filters for selective adsorption of harmful chemicals from water/air. Some of the factors which make this study unique and interesting are the following. We have developed know-how on surface potential and properties of biobased nanoparticles and its interaction with various metal ions, dyes, nitrates, proteins, DNA, hormones, antibiotics etc. This research till date have added tremendously to the scientific know-how to utilize biobased nanomaterials for water cleaning for the group and also in the research community around the globe.

Bio nanomaterials for medical applications

Narges Naseri, B. Deepa, Aji P. Mathew, Kristiina Oksman, and Lenart Girandon, Nanocellulose-Based Interpenetrating Polymer Network (IPN) Hydrogels for Cartilage Applications, Biomacromolecules 2016 17 (11), 3714-3723

Sultan S, Mathew AP. 3D printed scaffolds with gradient porosity based on a cellulose nanocrystal hydrogel. Nanoscale. 2018;10(9):4421–31. Found at: http://pubs.rsc.org/en/content/articlehtml/2018/nr/c7nr08966j

Nanocrystals and nanofibers based on cellulose, chitin, collagen etc have inherent properties like low toxicity, biocompatibility, biodegradability together with excellent mechanical properties and/or thermal stability which makes these nanoreinforments interesting candidates in biomedical applications. Our studies in this  research area indicated possibility to be used successfully as artificial ligaments and tendons, wound care materials, cartilage  regeneration etc  For eg. cellulose nanocrystal based nanocomposites developed by in-situ crosslinking with a hydrophilic matrix have resulted in hydrogels capable of taking up moisture as high as 900% of its original weight. These materials may have potential application in products for burn healing or controlled release of drugs. Chitin based nanofiber mats developed by electrospinning with potential application in wound dressing/burn healing was reported recently. Porous scaffolds for cartilage regeneration was also developed where biopolymers reinforced with nanocellulose have shown tremendous potential. We currently develop porous scaffolds for  medical application via 3D printing of  biobased inks.

Atomic force microscopy of nanostructure materials

Zhu C, Mathew AP. Nanocellulose-Functionalized AFM Probes for Investigating Surface Interactions by Force Spectroscopy. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-155369

Zhu C, Liu ,P. Mathew AP,  Advanced microscopy and spectroscopy reveal the adsorption and clustering of Cu (II) onto TEMPO-oxidized cellulose nanofibers

Nanoscale, 2017.

This ongoing research deals morphology studies of nanoparticles and nanostrctured materials. Measurements in air as well as liquid medium is developed in the group. We also work on understanding the surface functionality and specific interactions of nanocellulose with external entities as metal ions, dyes, DNA, protiens, polymer chains etc through colloidal probe (AFM) and advanced spectroscopy methods supported with DFT modelling . The aim is to gain deeper understanding into the surface properties of nanoparticles and exploit its potential as biobased functional entity. We work with Peak Force QNM mode to map mechanicalproperties of nanostructures in dry and wet conditions.

 
 
 
 
 
 

Aji Mathew´s lab:

Bio-based functional materials