Non-leaching, Highly Biocompatible Nanocellulose Surfaces That Efficiently Resist Fouling by Bacteria in an Artificial Dermis Model

Bi- and tricyclic diterpenoids: landmarks from a decade (2013-2023) in search of leads against infectious diseases

Covering: 2013 to 2023In an era where antimicrobial resistance severely threatens our ability to treat infections, the discovery of new drugs that belong to different chemical classes and/or bear original modes of action is urgently needed. In this case, diterpenoids comprise a productive field with a proven track record in providing new anti-infectives to tackle bacterial infections and malaria. This review highlights the potential of both naturally occurring and semi-synthetic bi- and tricyclic diterpenoids to become leads in search of new drugs to treat infections caused by bacteria, fungi, viruses and protozoan parasites. The literature from the last decade (2013-2023) is covered, focusing on naturally occurring and semi-synthetic bicyclic (labdanes and labdane-type) and tricyclic (all classes) diterpenoids, detailing their relevant biological activities in the context of infection, which are explained through structure-activity relationships.

In vitro and in vivo evaluation of diethyldithiocarbamate with copper ions and its liposomal formulation for the treatment of Staphylococcus aureus and Staphylococcus epidermidis biofilms

Surgical site infections (SSIs) are mainly caused by Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis) biofilms. Biofilms are aggregates of bacteria embedded in a self-produced matrix that offers protection against antibiotics and promotes the spread of antibiotic-resistance in bacteria. Consequently, antibiotic treatment frequently fails, resulting in the need for alternative therapies. The present study describes the in vitro efficacy of the Cu(DDC)₂ complex (2:1 M ratio of diethyldithiocarbamate (DDC^-) and Cu²⁺) with additional Cu²⁺ against S. aureus and S. epidermidis biofilms in models mimicking SSIs and in vitro antibacterial activity of a liposomal Cu(DDC)₂ + Cu²⁺ formulation. The in vitro activity on S. aureus and S. epidermidis biofilms grown on two hernia mesh materials and in a wound model was determined by colony forming unit (CFU) counting. Cu²⁺-liposomes and Cu(DDC)₂-liposomes were prepared, and their antibacterial activity was assessed in vitro using the alamarBlue assay and CFU counting and in vivo using a Galleria mellonella infection model. The combination of 35 μM DDC^- and 128 μM Cu²⁺ inhibited S. aureus and S. epidermidis biofilms on meshes and in a wound infection model. Cu(DDC)₂-liposomes + free Cu²⁺ displayed similar antibiofilm activity to free Cu(DDC)₂ + Cu²⁺, and significantly increased the survival of S. epidermidis-infected larvae. Whilst Cu(DDC)₂ + Cu²⁺ showed substantial antibiofilm activity in vitro against clinically relevant biofilms, its application in mammalian in vivo models is limited by solubility. The liposomal Cu(DDC)₂ + Cu²⁺ formulation showed antibiofilm activity in vitro and antibacterial activity and low toxicity in G. mellonella, making it a suitable water-soluble formulation for future application on infected wounds in animal trials.

Biobased Nanomaterials─The Role of Interfacial Interactions for Advanced Materials

This review presents recent advances regarding biomass-based nanomaterials, focusing on their surface interactions. Plant biomass-based nanoparticles, like nanocellulose and lignin from industry side streams, hold great potential for the development of lightweight, functional, biodegradable, or recyclable material solutions for a sustainable circular bioeconomy. However, to obtain optimal properties of the nanoparticles and materials made thereof, it is crucial to control the interactions both during particle production and in applications. Herein we focus on the current understanding of these interactions. Solvent interactions during particle formation and production, as well as interactions with water, polymers, cells and other components in applications, are addressed. We concentrate on cellulose and lignin nanomaterials and their combination. We demonstrate how the surface chemistry of the nanomaterials affects these interactions and how excellent performance is only achieved when the interactions are controlled. We furthermore introduce suitable methods for probing interactions with nanomaterials, describe their advantages and challenges, and introduce some less commonly used methods and discuss their possible applications to gain a deeper understanding of the interfacial chemistry of biobased nanomaterials. Finally, some gaps in current understanding and interesting emerging research lines are identified.

Neem extract-blended nanocellulose derived from jackfruit peel for antibacterial packagings

The use of jackfruit peel as a source for natural and fully biodegradable "nanocellulose" (NC) for the production of bioplastics with Azadirachta indica (A. indica) extracts and polyethylene glycol (PEG) for the antibacterial properties is investigated. The characterization of the biocomposite using FT-IR and WXRD was reported. The physicochemical properties including thickness, moisture content, water holding capacity, swelling, porosity, and biodegradability in soil were investigated. The incorporation of A. indica extract revealed an increased shelf life due to the strong antibacterial activity, and these biocomposites were degraded in soil within 60 days after the end use without any harm to the environment. Jackfruit-derived nanocellulose film blended with A. indica extract exhibited strong antibacterial activity against gram-positive and gram-negative food spoilage bacteria. Disc diffusion assay, live/dead assay, and CFU analysis confirmed the antibacterial property of the synthesized film. Moreover, the films clearly prevented the biofilm formation in bacteria. Thus, the developed bioplastics can be utilized as appropriate substitutes to food packaging materials and also for biomedical applications such as wound dressings.

Recent Advances on Biological Activities and Structural Modifications of Dehydroabietic Acid

Dehydroabietic acid is a tricyclic diterpenoid resin acid isolated from rosin. Dehydroabietic acid and its derivatives showed lots of medical and agricultural bioactivities, such as anticancer, antibacterial, antiviral, antiulcer, insecticidal, and herbicidal activities. This review summarized the research advances on the structural modification and total synthesis of dehydroabietic acid and its derivatives from 2015 to 2021, and analyzed the biotransformation and structure-activity relationships in order to provide a reference for the development and utilization of dehydroabietic acid and its derivatives as drugs and pesticides.

Cellulose-Based Nanofibril Composite Materials as a New Approach to Fight Bacterial Infections

Antibiotic resistant microorganisms have become an enormous global challenge, and are predicted to cause hundreds of millions of deaths. Therefore, the search for novel/alternative antimicrobial agents is a grand global challenge. Cellulose is an abundant biopolymer with the advantages of low cost, biodegradability, and biocompatibility. With the recent growth of nanotechnology and nanomedicine, numerous researchers have investigated nanofibril cellulose to try to develop an anti-bacterial biomaterial. However, nanofibril cellulose has no inherent antibacterial activity, and therefore cannot be used on its own. To empower cellulose with anti-bacterial properties, new efficient nanomaterials have been designed based on cellulose-based nanofibrils as potential wound dressings, food packaging, and for other antibacterial applications. In this review we summarize reports concerning the therapeutic potential of cellulose-based nanofibrils against various bacterial infections.

Precision Design of Antimicrobial Surfaces

The overall expectation from an antimicrobial surface has been high considering the need for efficiency in preventing the attachment and growth of pathogenic microbes, durability, safety to both humans and environment as well as cost-effectiveness. To date, antimicrobial surface design has been mostly conducted liberally, without rigorous consideration of establishing robust structure-activity relationships for each design strategy or of the use intended for a specific antimicrobial material. However, the variability among the domain bacteria, which is the most diverse of all, alongside the highly dynamic nature of the bacteria-surface interface have taught us that the likelihood of finding universal antimicrobial surfaces is low. In this perspective we discuss some of the current hurdles faced by research in this promising field, emphasizing the relevance and complexity of probing the bacteria-surface interface, and explain why we feel it would greatly benefit from a more streamlined ad-hoc approach.