Scale-up Feasibility Research Articles

A scoping review of cultivated meat techno-economic analyses to inform future research directions for scaled-up manufacturing.

Techno-economic analyses offer insights into how industrial cultivated meat (CM) production could achieve price parity with conventional meat. These analyses use scaling practices, data and facility designs for related bioprocessing fields, including large (≥20,000 l) stirred tank bioreactors and suspension-tolerant, continuously available cell lines. This approach is inconsistent with most primary CM literature, which parallels bench-scale tissue engineering. TEAs published to date demonstrate that, under the current technological paradigm, CM is unlikely to be competitive with conventional meat. Scale-up feasibility may hinge on cost-saving areas such as use of plant-based media components, food-grade aseptic conditions and extensive scaling of related supply chains. Research must address knowledge gaps including serum-free differentiation, new bioreactor designs and facility design before CM can become a viable alternative to animal-based meat production.

A novel temperature-controlled media milling device to produce drug nanocrystals at the laboratory scale

Poor aqueous solubility of preexisting and emerging drug molecules is a common issue faced in the field of pharmaceutics. To address this, particle size reduction techniques, including drug micro- and nanonisation have been widely employed. Nanocrystals (NCs), drug particles with particle sizes below 1 µm, offer high drug content, improved dissolution, and long-acting capabilities. Media milling is the most used method to prepare NCs using of-the-shelf machinery, both at the laboratory and industrial scales. However, early NCs development, especially when limited amounts of the active are available, require the use of milligram-scale media milling. This study introduces a novel mini-scale milling device (Mini-mill) that incorporates temperature control through a water-cooled jacket. The device was used to produce NCs of three model hydrophobic drugs, itraconazole, ivermectin and curcumin, with lowest particle sizes of 162.5 ± 0.4 nm, 178 ± 2 nm, and 116.7 ± 0.7 nm, respectively. Precise control of milling temperature was achieved at 15, 45, and 75°C, with drug dependent particle size reduction trends, with no adverse effects on the milling materials or polymorphic changes in the NCs, as confirmed by calorimetric analysis. Finally, a scale-up feasibility study was carried out in a lab-scale NanoDisp®, confirming that the novel Mini-mills are a material-efficient tool for early formulation development, with potential for scale-up to commercial mills.

EFluorination for the Rapid Synthesis of Carbamoyl Fluorides from Oxamic Acids.

In this letter, we disclose the anodic oxidation of oxamic acids in the presence of Et3N·3HF as a practical, scalable, and robust method to rapidly access carbamoyl fluorides from readily available and stable precursors. The simplicity of this method also led us to develop the first flow electrochemical preparation of carbamoyl fluorides, demonstrating scale-up feasibility as a proof of concept.

Iron dopant in zinc oxide nanorods-based photoanode using chemical bath deposition method for photoelectrochemical water-splitting

Utilization of zinc oxide as a photoanode in photoelectrochemical (PEC) water splitting is cost-effective and environmentally friendly choices compared to noble metals, although some enhancements are required to address the limited light absorption and significant charge recombination. Iron as metal doping and nanorod structure, on the other hand, offers solutions to overcome these limitations. An in-depth study employing iron-doped zinc oxide nanorods using various concentrations of iron fabricated through a chemical bath deposition (CBD) method due to its high-quality results and scale-up feasibility, shows enhanced structures, electrical characteristics, optical properties, charge transfer speed, and overall effectiveness in converting solar energy to hydrogen. This dopant was effectively integrated into the photoanode, resulting in a reduction of the bandgap to 3.19 eV and the creation of nanorods that are both thinner and longer. The photocurrent density for the oxygen evolution reaction (OER) is 6 mA/cm2, and for the hydrogen evolution reaction (HER), it is 1.3 mA/cm2. Electrochemical Impedance Spectroscopy shows lower resistance and an improved diffusion coefficient, resulting in reduced energy requirements for hydrogen production. The solar-to-hydrogen efficiency is also reported at 4.7%. This method shows potential for future progress and possible performance improvements.

Lipid Nanocarriers-Enabled Delivery of Antibiotics and Antimicrobial Adjuvants to Overcome Bacterial Biofilms.

The opportunistic bacteria growing in biofilms play a decisive role in the pathogenesis of chronic infectious diseases. Biofilm-dwelling bacteria behave differently than planktonic bacteria and are likely to increase resistance and tolerance to antimicrobial therapeutics. Antimicrobial adjuvants have emerged as a promising strategy to combat antimicrobial resistance (AMR) and restore the efficacy of existing antibiotics. A combination of antibiotics and potential antimicrobial adjuvants, (e.g., extracellular polymeric substance (EPS)-degrading enzymes and quorum sensing inhibitors (QSI) can improve the effects of antibiotics and potentially reduce bacterial resistance). In addition, encapsulation of antimicrobials within nanoparticulate systems can improve their stability and their delivery into biofilms. Lipid nanocarriers (LNCs) have been established as having the potential to improve the efficacy of existing antibiotics in combination with antimicrobial adjuvants. Among them, liquid crystal nanoparticles (LCNPs), liposomes, solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs) are promising due to their superior properties compared to traditional formulations, including their greater biocompatibility, higher drug loading capacity, drug protection from chemical or enzymatic degradation, controlled drug release, targeted delivery, ease of preparation, and scale-up feasibility. This article reviews the recent advances in developing various LNCs to co-deliver some well-studied antimicrobial adjuvants combined with antibiotics from different classes. The efficacy of various combination treatments is compared against bacterial biofilms, and synergistic therapeutics that deserve further investigation are also highlighted. This review identifies promising LNCs for the delivery of combination therapies that are in recent development. It discusses how LNC-enabled co-delivery of antibiotics and adjuvants can advance current clinical antimicrobial treatments, leading to innovative products, enabling the reuse of antibiotics, and providing opportunities for saving millions of lives from bacterial infections.

Development of O/W Pickering Emulsions Stabilized with Leek Leaf Trimmings Using Batch and Continuous Modes

Vegetable trimmings can be used to stabilize edible O/W Pickering emulsions. The lignocellulosic biomass (LCB) from the leek trimmings was mechanically treated to produce high-yield lignocellulose micro and nanofibrils (LCF) using a high-pressure homogenizer (HPH). Different O/W phase ratios (20/80, 30/70, and 40/60 wt.%) were studied. The use of the micro/nano cellulosic fibers increased the stabilization of the Pickering emulsions by 30–40%. In all cases, stable emulsions were obtained, with emulsification indexes > 92%. The respective stabilization mechanism was thoroughly analysed from confocal laser scanning, and cryo-scanning electron microscopy, which showed the fibers are not coating the droplets but forming a network that traps the droplets and prevents coalescence. The most stable batch formulations, O/W 30/70 wt.% (LCB 4.2 wt.%) and O/W 40/60 wt.% (LCB 3.6 wt.%), were also studied in continuous mode using NETmix technology. Results show the scale-up feasibility of the production of Pickering emulsions containing LCF. Most significantly, this work proposes a continuous process to produce Pickering emulsions stabilized with a natural biopolymer extracted from leek trimmings, which is suitable to industrial manufacturing processes. This valorizes the vegetable trimmings that are usually tossed away as waste, creating new market niches and business models based on circular economy concepts.Graphical

Polyhydroxyalkanoates in emerging recycling technologies for a circular materials economy

This paper discusses the scale-up feasibility and industrial adoption of polyhydroxyalkanoates (PHAs), emphasizing the need to link PHA development with recycling technologies and highlighting strategies for designing PHAs for closed-loop recycling.

Development and characterization of inhaled nintedanib-loaded PLGA nanoparticles using scalable high-pressure homogenization technique

Presently, non-invasive targeted drug delivery to the lungs represents a routinely investigated approach to treat challenging disorders such as pulmonary fibrosis. Nintedanib (Nint) is an FDA-approved drug for treating idiopathic pulmonary fibrosis and certain interstitial lung diseases. Nint acts as a multiple tyrosine kinase inhibitor, demonstrating anti-neoplastic effects in non-small cell lung cancer. However, limitations of oral administration of Nint include low bioavailability and high dose requirement for adequate therapeutic efficacy, resulting in adverse effects like abdominal pain, sickness, diarrhea, and vomiting. In this project, Nint was reformulated into PLGA nanoparticles (Nint-NPs) for direct-lung administration to address these deficiencies and enhance its potential. In this project, Nint-NPs were designed utilizing a high-pressure homogenization (HPH) approach with excellent reproducibility and scale-up feasibility. Selected Nint-NP formulation revealed 43.3 ± 4.0 % of entrapment efficiency and 179.8 ± 3.1 nm of size. In-vitro release study showed an initial burst release of 36.0 ± 7.5 % within 30 min, followed by sustained release up to 71.0 ± 4.3 % by 96 h. Further, Nint-NPs were found to be stable after 1-month of storage in refrigerated and accelerated conditions. Interestingly, the results of lung deposition demonstrated ideal MMAD values less than 5 μm in all three nebulizer types tested (jet, breath-actuated jet, and vibrating mesh nebulizers), indicating Nint-NPs are appropriate for deep-lung delivery. In-vitro cellular uptake analysis exhibited higher internalization of NPs in alveolar epithelial cells and lung fibroblasts while avoiding macrophage uptake. Toxicity studies on normal lung cells indicated Nint-NPs were safe for use. Taken together, inhalation therapy of Nint-NPs offers a favorable alternative to oral capsules for treating respiratory diseases.

Comparison study of supercritical water gasification for hydrogen production on a continuous flow versus a batch reactor

This study compares batch and continuous supercritical water gasification (SCWG) processes for green hydrogen production from biomass. It offers insights for optimizing processes, enhancing yields, quality, and energy efficiency, assessing scale-up feasibility, and supporting techno-economic analyses. Glucose, glycerol, and black liquor were SCWG-treated at 500 °C with K2CO3 catalyst in a self-built continuous-flow reactor (150 g/h) and a batch reactor (75 mL). Comparisons primarily focused on gas product yields. Batch reactors outperformed continuous-flow reactors in hydrogen (glucose: 1.53 to 0.9 mmol/g, glycerol: 7.22 to 1.14 mmol/g, black liquor: 2.88 to 1.74 mmol/g) and total gas yields due to differences in reaction time and heating behavior. Temperature effects on continuous operation (450–600 °C) were studied, with glycerol showing the highest hydrogen yield increase (from 1.21 to 4.30 mmol/g). The study discusses the applicability of both reactors for biomass SCWG processes and their implications for sustainable green hydrogen production from renewable feedstocks.

Meloxicam emulgel potently suppressed cartilage degradation in knee osteoarthritis: Optimization, formulation, industrial scalability and pharmacodynamic analysis

Background and objectiveMeloxicam (MLX) is prescribed for the management of pain and inflammation allied with osteoarthritis (OA). However, MLX causes intestinal damage in long term administration. Hence, meloxicam loaded emulgel (MLX-emulgel) was optimized, formulated and examined under stringent parameters in monosodium-iodoacetate (MIA) induced knee OA in Wistar rats. Methods and resultsNanoemulsion of MLX was fabricated by ultrasonication and microfluidization method with a droplet size of 66.81 ± 5.31-nm and zeta potential of −24.6 ± 0.72-mV. Further, MLX nanoemulsion was optimized with centrifugation, heating-cooling cycles and transmittance parameters in addition to scale-up feasibility with microfluidizer. Post optimization, MLX-nanoemulsion was tailored as emulgel with Carbopol Ultrez 10 NF and assessed for pH, rheology, textural properties, assay and stability features. The in-vitro release study revealed the Korsmeyer-Peppas release kinetics and ex-vivo skin permeation was improved by 6.71-folds. The skin distribution of MLX-emulgel evinced the transfollicular mode of permeation. In-vivo study indicated the protective action of MLX-emulegl expressed in terms of inflammatory cyctokines level, X-ray analysis of knee joints of rats, histopathology and OARSI (Osteoarthritis Research Society International) scoring. MLX-emulgel treated group displayed lower (P < 0.001) level of COX-2 intensity as compared to positive control group. However, it was comparable (P > 0.05) to the normal control group, MLX oral dispersion, i.v. solution and etoricoxib gel groups. MLX-emulgel showcased an alternative to the long term usage of analgesics for relieving the symptoms of knee OA. ConclusionMLX-emulgel may be a potential candidate for translating in to a clinically viable dosage form in the management of knee OA.

Controlled Interfacial Polymer Self-Assembly Coordinates Ultrahigh Drug Loading and Zero-Order Release in Particles Prepared under Continuous Flow.

Microparticles are successfully engineered through controlled interfacial self-assembly of polymers to harmonize ultrahigh drug loading with zero-order release of protein payloads. To address their poor miscibility with carrier materials, protein molecules are transformed into nanoparticles, whose surfaces are covered with polymer molecules. This polymer layer hinders the transfer of cargo nanoparticles from oil to water, achieving superior encapsulation efficiency (up to 99.9%). To control payload release, the polymer density at the oil-water interface is enhanced, forming a compact shell for microparticles. The resultant microparticles can harvest up to 49.9% mass fraction of proteins with zero-order release kinetics in vivo, enabling an efficient glycemic control in type 1 diabetes. Moreover, the precise control of engineering process offered through continuous flow results in high batch-to-batch reproducibility and, ultimately, excellent scale-up feasibility.

Solid Lipid Nanoparticles: Applications and Prospects in Cancer Treatment.

Recent advancements in drug delivery technologies paved a way for improving cancer therapeutics. Nanotechnology emerged as a potential tool in the field of drug delivery, overcoming the challenges of conventional drug delivery systems. In the field of nanotechnology, solid lipid nanoparticles (SLNs) play a vital role with a wide range of diverse applications, namely drug delivery, clinical medicine, and cancer therapeutics. SLNs establish a significant role owing to their ability to encapsulate hydrophilic and hydrophobic compounds, biocompatibility, ease of surface modification, scale-up feasibility, and possibilities of both active and passive targeting to various organs. In cancer therapy, SLNs have emerged as imminent nanocarriers for overcoming physiological barriers and multidrug resistance pathways. However, there is a need for special attention to be paid to further improving the conceptual understanding of the biological responses of SLNs in cancer therapeutics. Hence, further research exploration needs to be focused on the determination of the structure and strength of SLNs at the cellular level, both in vitro and in vivo, to develop potential therapeutics with reduced side effects. The present review addresses the various modalities of SLN development, SLN mechanisms in cancer therapeutics, and the scale-up potential and regulatory considerations of SLN technology. The review extensively focuses on the applications of SLNs in cancer treatment.

Perspectives on cutting-edge nanoparticulate drug delivery technologies based on lipids and their applications.

Numerous nanotech arenas in therapeutic biology have recently provided a scientific platform to manufacture a considerable swath of unique chemical entities focusing on drugs. Recently, nanoparticulate drug delivery systems have emerged to deliver a specific drug to a specified site. Among all other carriers, lipids possess features exclusive to nanostructured dosage forms. The bioavailability of orally administered drugs is typically negatively affected by their poor water solubility, resulting from the unique chemical moieties introduced. Because of their unique advantages, lipid nanoparticles must become increasingly predictable as a robust delivery mechanism. The enhanced biopharmaceutical properties and significance of lipid-based targeting technologies such as liposomes, niosomes, solid lipid nanoparticles and micelles are highlighted in this review. Pharmaceutical implications of lipid nanocarriers for the transport and distribution of various therapeutic agents, such as biotechnological products and small pharmaceutical molecules, is a booming topic. Lipid nanoparticles as drug delivery systems have many appealing properties, including high biocompatibility, ease of preparation, tissue specificity, avoidance of reticuloendothelial systems, delayed drug release, scale-up feasibility, nontoxicity and targeted delivery. The use of lipid nanoparticles to enhance the transport of biopharmaceuticals is currently considered state-of-the-art. Similarly, we critically examine the upcoming guidelines that therapeutic scientists should handle.

Nanoemulsion Containing Kojic Dipalmitate and Rosehip Oil: A Promising Formulation to Treat Melasma.

Melasma is a hard-to-treat hyperpigmentation disorder. Combined incorporation of kojic dipalmitate (KDP), the esterified form of kojic acid, and rosehip oil, an oil with antioxidant and skin-regenerating properties, into nanocarrier systems appears to be a suitable strategy to develop high-performance formulations. A high-energy method (Ultra-Turrax®) was used to develop nanoemulsions containing up to 2 mg/mL KDP, 5% rosehip oil, and 7.5% surfactant. Formulations were characterized regarding droplet size, size distribution, pH, density, morphology, KDP content, incorporation efficiency, and stability under different temperature conditions. A scale-up study was conducted. Skin permeation, antioxidant potential, and tyrosinase inhibitory activity were assessed in vitro. Cell viability studies were also performed. Results showed that nanoemulsions containing 1 and 2 mg/mL KDP had incorporation efficiencies greater than 95%, droplet size smaller than 130 nm, suitable size distribution, zeta potential of approximately -10 mV, and good stability over 30 days of refrigerated storage. The nanoemulsion containing 1 mg/mL KDP was chosen for further evaluation because it had lower nanocrystal formation, greater scale-up feasibility and allowed KDP permeation up to the epidermis similarly than observed for 2 mg/mL KDP. This formulation (1 mg/mL KDP) showed antioxidant and depigmenting efficacy, close to that of 1 mM ascorbic acid. No cytotoxicity was observed in formulations concentrations ranging from 0.06% to 1%.

Comparison of biopolymer scaffolds for the fabrication of skin substitutes in a porcine wound model.

This study compared three acellular scaffolds as templates for the fabrication of skin substitutes. A collagen-glycosaminoglycan (C-GAG), a biodegradable polyurethane foam (PUR) and a hybrid combination (PUR/C-GAG) were investigated. Scaffolds were prepared for cell inoculation. Fibroblasts and keratinocytes were serially inoculated onto the scaffolds and co-cultured for 14 days before transplantation. Three pigs each received four full-thickness 8cm × 8cm surgical wounds, into which a biodegradable temporising matrix (BTM) was implanted. Surface seals were removed after integration (28 days), and three laboratory-generated skin analogues and a control split-thickness skin graft (STSG) were applied for 16 weeks. Punch biopsies confirmed engraftment and re-epithelialisation. Biophysical wound parameters were also measured and analysed. All wounds showed greater than 80% epithelialisation by day 14 post-transplantation. The control STSG displayed 44% contraction over the 16 weeks, and the test scaffolds, C-GAG 64%, Hybrid 66.7% and PUR 67.8%. Immunohistochemistry confirmed positive epidermal keratins and basement membrane components (Integrin alpha-6, collagens IV and VII). Collagen deposition and fibre organisation indicated the degree of fibrosis and scar produced for each graft. All scaffold substitutes re-epithelialised by 4 weeks. The percentage of original wound area for the Hybrid and PUR was significantly different than the STSG and C-GAG, indicating the importance of scaffold retainment within the first 3 months post-transplant. The PUR/C-GAG scaffolds reduced the polymer pore size, assisting cell retention and reducing the contraction of in vitro collagen. Further investigation is required to ensure reproducibility and scale-up feasibility.

Comparison of Techniques for Drying Cellulose Nanocrystal Pickering Emulsions into Oil Powders

A recent push for surfactant-free products driven by environmental awareness has propelled the use of bio-based materials in place of petroleum-derived components. However, both the formulation and processing need to be considered for scale-up feasibility and environmental sustainability. This work investigated the drying of corn oil-in-water emulsions stabilized by cellulose nanocrystals (CNCs), methyl cellulose (MC), and tannic acid via freeze drying, spray freeze drying, and spray drying. All three techniques produced oil powders with low moisture content and high encapsulated oil content (>90%). The oil powders could be redispersed in water by hand shaking to reform the original emulsion and could be stored dry for weeks without oil leakage (in the fridge). The release of oil from the powders on hydrophobic substrates (at room temperature) was controlled by changing the CNC and MC stabilizer content; the spray freeze dried samples were the most tunable. The three drying techniques imparted different surface morphologies that were linked to powder redispersibility and oil release properties. The lack of freezing (and associated ice crystal growth) in spray drying minimized oil droplet agglomeration, and it was the fastest, most scalable, and least energy-intensive drying technique of the three, but it was also the most sensitive to emulsion concentration and susceptible to instabilities associated with high temperature and shear stress. It was demonstrated that essential oils with a range of interfacial tensions and volatilities (e.g., jojoba, lavender, tea tree oil) could also be encapsulated in spray dried oil powders. This general encapsulation strategy can be tailored based on the drying technique selected, uses plant-based industrially-produced feedstocks, works with commercially relevant oils, and will hopefully contribute to the development of sustainable emulsions and oil powders for food, pharmaceutical, agricultural, and cosmetic applications.

Magnetically recoverable, non-toxic, leach resistant aluminum ferrite (AlFeO3) photocatalyst for wastewater remediation

The practical use of photocatalyst in wastewater treatment is mainly hindered due to the recoverability of the catalyst. This can be addressed by the ferrite-based compounds which enable magnetic recoverability. In this work, Aluminium Ferrite (AlFeO3), a perovskite-based magnetic photocatalyst is successfully synthesized and its photocatalytic performance is tested. For the scale-up feasibility, the material is tested in static polluted water. AlFeO3 shows effective degradation of textile dye pollutants: 99% of Rhodamine B (RhB) in 180 min and 94% of Methyl orange (MO) in 270 min at the static condition, under visible-light illumination. It also exhibits UV photoactivity which implies AlFeO3 is a potential candidate for sunlight-driven wastewater treatment. The degradation rate is increased by 1.5 times when air is bubbled during photocatalysis. The catalyst is magnetically retrieved from the treated water and reused over 5 cycles with only ∼4% efficiency loss. The environmental viability of AlFeO3 is tested for the first time using cell toxicity studies and catalyst leaching in the treated water. The results indicate that more than 90% of L929 fibroblast cells are viable even when incubated with AlFeO3 for 24 h. The negligible trace of Al and Fe presence in the treated water shows that AlFeO3 is also leach resistant. Hence, AlFeO3 is a UV–Visible-light-driven, easy-to-recover, recyclable, and eco-friendly photocatalyst that has the potential for practical use.

Revisiting the Effect of U-Bends, Flow Parameters, and Feasibility for Scale-Up on Residence Time Distribution Curves for a Continuous Bioprocessing Oscillatory Baffled Flow Reactor.

An oscillatory baffled flow reactor (OBR) has been designed with 60 interbaffled cells. The baffled columns of 40 mm internal diameter together result in a reactor length of 5740 mm. The oscillatory amplitude and frequency were in the range of 2–12 mm and 0.3–2 Hz, respectively. The report investigates the impact of U-bends and the number of reactor sections on axial dispersion for scale-up feasibility. A prediction model using operating parameters has been developed to maximize plug flow conditions using the tanks-in-series (TiS) model. The maximum TiS value was 13.38 in a single column compared to 43.68 in the full reactor at a velocity ratio of 2.27 using oscillatory parameters 8 mm and 0.3 Hz. The mixing efficiency along the reactor was found to decrease after each column at amplitudes <6 mm compared to amplitudes up to 12 mm, where a negligible impact was observed. U-bend geometry had a significant role in the decrease of TiS values.

Enhanced Production of C30 Carotenoid 4,4'-Diaponeurosporene by Optimizing Culture Conditions of Lactiplantibacillus plantarum subsp. plantarum KCCP11226T.

The rising demand for carotenoids can be met by microbial biosynthesis as a promising alternative to chemical synthesis and plant extraction. Several species of lactic acid bacteria (LAB) specifically produce C30 carotenoids and offer the added probiotic benefit of improved gut health and protection against chronic conditions. In this study, the recently characterized Lactiplantibacillus plantarum subsp. plantarum KCCP11226T produced the rare C30 carotenoid, 4,4'-diaponeurosporene, and its yield was optimized for industrial production. The one-factor-at-a-time (OFAT) method was used to screen carbon and nitrogen sources, while the abiotic stresses of temperature, pH, and salinity, were evaluated for their effects on 4,4'-diaponeurosporene production. Lactose and beef extract were ideal for optimal carotenoid production at 25°C incubation in pH 7.0 medium with no salt. The main factors influencing 4,4'-diaponeurosporene yields, namely lactose level, beef extract concentration and initial pH, were enhanced using the Box-Behnken design under response surface methodology (RSM). Compared to commercial MRS medium, there was a 3.3-fold increase in carotenoid production in the optimized conditions of 15% lactose, 8.3% beef extract and initial pH of 6.9, producing a 4,4'-diaponeurosporene concentration of 0.033 A470/ml. To substantiate upscaling for industrial application, the optimal aeration rate in a 5 L fermentor was 0.3 vvm. This resulted in a further 3.8-fold increase in 4,4'-diaponeurosporene production, with a concentration of 0.042 A470/ml, compared to the flask-scale cultivation in commercial MRS medium. The present work confirms the optimization and scale-up feasibility of enhanced 4,4'-diaponeurosporene production by L. plantarum subsp. plantarum KCCP11226T.

The First-in-Human Synthetic Glycan-Based Conjugate Vaccine Candidate against Shigella.

Shigella, the causative agent of shigellosis, is among the main causes of diarrheal diseases with still a high morbidity in low-income countries. Relying on chemical synthesis, we implemented a multidisciplinary strategy to design SF2a-TT15, an original glycoconjugate vaccine candidate targeting Shigella flexneri 2a (SF2a). Whereas the SF2a O-antigen features nonstoichiometric O-acetylation, SF2a-TT15 is made of a synthetic 15mer oligosaccharide, corresponding to three non-O-acetylated repeats, linked at its reducing end to tetanus toxoid by means of a thiol-maleimide spacer. We report on the scale-up feasibility under GMP conditions of a high yielding bioconjugation process established to ensure a reproducible and controllable glycan/protein ratio. Preclinical and clinical batches complying with specifications from ICH guidelines, WHO recommendations for polysaccharide conjugate vaccines, and (non)compendial tests were produced. The obtained SF2a-TT15 vaccine candidate passed all toxicity-related criteria, was immunogenic in rabbits, and elicited bactericidal antibodies in mice. Remarkably, the induced IgG antibodies recognized a large panel of SF2a circulating strains. These preclinical data have paved the way forward to the first-in-human study for SF2a-TT15, demonstrating safety and immunogenicity. This contribution discloses the yet unreported feasibility of the GMP synthesis of conjugate vaccines featuring a unique homogeneous synthetic glycan hapten fine-tuned to protect against an infectious disease.