Stabilizers and their interaction with formulation components in frozen and freeze-dried protein formulations

Aqueous Solubility of Sodium and Chloride Salts of Glycine─"Uncommon" Common-Ion Effects of Self-Titrating Solids

Although glycine is the simplest of the amino acids, its solution and solid-state properties are far from straightforward. The aqueous solubility of glycine plays an important role in various applications, including nutrition, food products, biodegradable plastics, and drug development. There is evidence that glycine in subsaturated pH 3-8 solutions forms a dimer, as suggested by several techniques. However, what takes place below pH 3 and above pH 8 in saturated solutions has been sparsely explored and is thought to exhibit complex properties. Although the solubility measurements in the pH 0-13 range have been reported by several groups, the interlaboratory variance between the data below pH 3 and above pH 8 has been high. In a couple of cases, there appears to be no pH dependence on solubility across the wide pH range, even though the reported glycine pKa values are 2.34 and 9.61. The solubility of the salt forms of glycine is largely uncharacterized. The solubility products of the simplest salts, glycine hydrochloride and sodium glycinate, appear not to have been published. In this study, five series of precision solubility measurements of glycine and its salts were performed at 25 °C, covering the range of pH -0.4 to 12.4, where in each case, just enough glycine was added to reach saturation. We have developed an equilibrium model to rationalize the complicated salt regions. Elemental analysis of isolated solids from saturated solutions supports the speciation model. At least three different salt forms have been indicated in acidic solutions and one salt form in alkaline solutions. Solubility products are reported here. The presence of a water-soluble cationic dimer is also proposed. Data analysis was performed with the aid of the pDISOL-X computer program. Activity corrections based on the Stokes-Robinson hydration theory have been implemented in saturated solutions with ionic strength in some cases exceeding 5 M. Although salt solubility is not a constant, since it depends on two independently controlled reactant concentrations, the salt solubility product is commonly expected to be a constant. However, in the glycine salt region below pH 3, our solubility measurements demonstrate that the solubility products depend on the total amount of added glycine in a saturated solution. We view this as an "uncommon" common-ion effect.

Analytical and drug delivery strategies for short peptides: From manufacturing to market

In recent times, biopharmaceuticals have gained attention because of their tremendous potential to benefit millions of patients globally by treating widespread diseases such as cancer, diabetes and many rare diseases. Short peptides (SP), also termed as oligopeptides, are one such class of biopharmaceuticals, that are majorly involved in efficient functioning of biological systems. Peptide chains that are 2-20 amino acids long are considered as oligopeptides by researchers and are some of the functionally vital compounds with widespread applications including self-assembly material for drug delivery, targeting ligands for precise/specific targeting and other biological uses. Using functionalised biomacromolecules such as short chained peptides, helps in improving pharmacokinetic properties and biodistribution profile of the drug. Apart from this, functionalised SP are being employed as cell penetrating peptides and prodrug to specifically and selectively target tumor sites. In order to minimize any unwanted interaction and adverse effects, the stability and safety of SP should be ensured throughout its development from manufacturing to market. Formulation development and characterization strategies of these potential molecules are described in the following review along with various applications and details of marketed formulations.

Exploring vacuum foam drying as an alternative to freeze-drying and spray drying for a human lipase

This article compares and explores vacuum foam-drying as an alternative drying technology to freeze-drying and spray drying for a recombinant human lipase as the model protein. Materials characteristics such as structure, surface composition and the solid-state properties of the dry materials were compared and investigated. Moreover, the technical functionality in terms of reconstitution characteristics and the lipase stability were also investigated. The stability of the lipase was evaluated through activity measurements. Sucrose and dextran D40 (40 kDa) were used as matrix former and the surfactant α-dodecyl maltoside was used as surface active additive. The study demonstrated that the drying technique greatly influenced the material structure and composition which in turn affected the reconstitution characteristics. The lipase was overrepresented at the material surface in declining order spray-dried > vacuum foam-dried > freeze-dried. The lipase activity was retained up to 10 % lipase content in solids, but at 20 % lipase a loss of activity was observed for all drying techniques. Phase separation in the solid material may be an explanation. Vacuum foam-drying shows promise as an alternative drying technique for the lipase, and potentially other proteins.

Trehalose and Mannitol Based Lyoprotetion of Taq DNA Polymerase for Cold-chain-free Long-term Storage

Polymerase chain reactions (PCR) are most reliable and precise means for nucleic acid analysis of biological samples. A cold-chain system with temperature at around -20°C is generally necessary for storage and transportation of PCR-related reagents. In order to facilitate ambient temperature storage and transportation, this study prepared Taq DNA polymerase and 5 × HS-Taq Mix (as low as 0.5 U/sample) into stable solid formulations using an optimized freeze-drying process and lyoprotectant formulations comprising trehalose dihydrate (3.3∼5%, w/v) and mannitol (10%, w/v). The lyocakes were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). In the optimized freeze-drying process, trehalose dihydrate mainly formed an amorphous structure and acted as both cryoprotectant and lyoprotectant, while mannitol crystallized to serve as a bulking agent. The enzyme activities of Taq and 5 × HS-Taq Mix samples were measured via real-time quantitative PCR (qPCR). Long-term storage stability test demonstrated that freeze-dried samples with optimized formulations showed no remarkable reduction in amplification efficiencies for target sequence compared to freshly prepared corresponding samples after being stored at 37°C and 55% relative humidity (RH) for 0, 1, 4, 8 and 12 weeks.

Sweet corn phytoglycogen dendrimers as a lyoprotectant for dry-state protein storage

Protein biotherapeutics typically require expensive cold-chain storage to maintain their fold and function. Packaging proteins in the dry state via lyophilization can reduce these cold-chain requirements. However, formulating proteins for lyophilization often requires extensive optimization of excipients that both maintain the protein folded state during freezing and drying (i.e., "cryoprotection" and "lyoprotection"), and form a cake to carry the dehydrated protein. Here we show that sweet corn phytoglycogens, which are glucose dendrimers, can act as both a protein lyoprotectant and a cake-forming agent. Phytoglycogen (PG) dendrimers from 16 different maize sources (PG1-16) were extracted via ethanol precipitation. PG size was generally consistent at ~70-100 nm for all variants, whereas the colloidal stability in water, protein contaminant level, and maximum density of cytocompatibility varied for PG1-16. 10 mg/mL PG1, 2, 9, 13, 15, and 16 maintained the activity of various proteins, including green fluorescent protein, lysozyme, β-galactosidase, and horseradish peroxidase, over a broad range of concentrations, through multiple rounds of lyophilization. PG13 was identified as the lead excipient candidate as it demonstrated narrow dispersity, colloidal stability in phosphate-buffered saline, low protein contaminants, and cytocompatibility up to 10 mg/mL in NIH3T3 cell cultures. All dry protein-PG13 mixtures had a cake-like appearance and all frozen protein-PG13 mixtures had a Tg' of ~ -26°C. The lyoprotection and cake-forming properties of PG13 were density-dependent, requiring a minimum density of 5 mg/mL for maximum activity. Collectively these data establish PG dendrimers as a new class of excipient to formulate proteins in the dry state.

Molecular-level insight into the effects of low moisture and trehalose on the thermostability of β-glucosidase

The high temperature induces conformational changes in β-glucosidase, making it inactive and limiting its application field. In this paper, the effect of trehalose on the thermostability of β-glucosidase from low-moisture Hevea brasiliensis seeds was investigated. The results showed that the residual enzyme activities of β-glucosidase supplemented with trehalose after high-temperature treatment were significantly higher than that of the control group. The improvement of thermostability could be explained by low-field nuclear magnetic resonance (LF-NMR) and molecular dynamics (MD) simulations at the molecular level. Moreover, adding trehalose increased the water activity and water content of β-glucosidase, leading to a more stable conformation. Trehalose replaced some water and formed a stable network of hydrogen bonds with protein and surrounding water. The glass formed by trehalose also reduced molecular movement, thus providing good protection for enzymes.

Formulation and Ex Vivo Evaluation of Ivermectin Within Different Nano-Drug Delivery Vehicles for Transdermal Drug Delivery

Background/Objectives: Ivermectin gained widespread attention as the "miracle drug" during the coronavirus disease 2019 (COVID-19) pandemic. Its inclusion in the 21st World Health Organization (WHO) List of Essential Medicines is attributed to its targeted anti-helminthic response, high efficacy, cost-effectiveness and favorable safety profile. Since the late 2000s, this bio-inspired active pharmaceutical ingredient (API) gained renewed interest for its diverse therapeutic capabilities. However, producing ivermectin formulations does remain challenging due to its poor water solubility, resulting in low bioavailability after oral administration. Therefore, the transdermal drug delivery of ivermectin was considered to overcome these challenges, which are observed after oral administration. Methods: Ivermectin was incorporated in a nano-emulsion, nano-emulgel and a colloidal suspension as ivermectin-loaded nanoparticles. The nano-drug delivery vehicles were optimized, characterized and evaluated through in vitro membrane release studies, ex vivo skin diffusion studies and tape-stripping to determine whether ivermectin was successfully released from its vehicle and delivered transdermally and/or topically throughout the skin. This study concluded with cytotoxicity tests using the methyl thiazolyl tetrazolium (MTT) and neutral red (NR) assays on both human immortalized epidermal keratinocytes (HaCaT) and human immortalized dermal fibroblasts (BJ-5ta). Results: Ivermectin was successfully released from each vehicle, delivered transdermally and topically throughout the skin and demonstrated little to no cytotoxicity at concentrations that diffused through the skin. Conclusions: The type of nano-drug delivery vehicle used to incorporate ivermectin influences its delivery both topically and transdermally, highlighting the dynamic equilibrium between the vehicle, the API and the skin.

Investigation of Protein Therapeutics in Frozen Conditions Using DNP MAS NMR: A Study on Pembrolizumab

The success of modern biopharmaceutical products depends on enhancing the stability of protein therapeutics. Freezing and thawing, which are common thermal stresses encountered throughout the lifecycle of drug substances, spanning protein production, formulation design, manufacturing, storage, and shipping, can impact this stability. Understanding the physicochemical and molecular behaviors of components in biological drug products at temperatures relevant to manufacturing and shipping is essential for assessing stability risks and determining appropriate storage conditions. This study focuses on the stability of high-concentration monoclonal antibody (mAb) pembrolizumab, the drug substance of Keytruda (Merck & Co., Inc., Rahway, NJ, United States), and its excipients in a frozen solution. By leveraging dynamic nuclear polarization (DNP), we achieve more than 100-fold signal enhancements in solid-state NMR (ssNMR), enabling efficient low-temperature (LT) analysis of pembrolizumab without isotopic enrichment. Through both ex situ and in situ ssNMR experiments conducted across a temperature range of 297 to 77 K, we provide insights into the stability of crystalline pembrolizumab under frozen conditions. Importantly, utilizing LT magic-angle spinning (MAS) probes allows us to study molecular dynamics in pembrolizumab from room temperature down to liquid nitrogen temperatures (<100 K). Our results demonstrate that valuable insights into protein conformation and dynamics, crystallinity, and the phase transformations of excipients during the freezing of the formulation matrix can be readily obtained for biological drug products. This study underscores the potential of LT-MAS ssNMR and DNP techniques for analyzing protein therapeutics and vaccines in frozen solutions.

Effects of supplementation with freeze-dried Clostridium butyricum powder after replacement of fishmeal with cottonseed protein concentrate on growth performance, immune response, and intestinal microbiota of Litopenaeus vannamei

The present study was designed to investigate the effects of supplementation with freeze-dried Clostridium butyricum (CB) powder on the growth, immune function and intestinal health of Litopenaeus vannamei after replacing fishmeal in the diet with cottonseed protein concentrate (CPC). Six treatment groups were designed, namely the control group (CON, 25% fish meal) and five alternative groups (CPC replacing 40% fishmeal protein in the control group). Based on the alternative group, 0%, 0.065%, 0.26%, 1.04%, and 4.16% of freeze-dried CB bacterial powder (4.6 × 108 CFU/g) were added, recorded as CB 0, CB 0.065, CB 0.26, CB 1.04, and CB 4.16, respectively. Each treatment had 3 replicates of 40 shrimps (0.29 ± 0.01 g) each and breeding for 8 weeks. After the experiment, serum enzyme activities, muscle amino acids, and intestinal parameters (short-chain fatty acids, digestive enzymes, gene expression, and microbiota) were tested to explore the effects of freeze-dried CB powder in shrimp aquaculture. The results showed that the CB1.04 group had the highest final body weight, weight gain rate, and specific growth ratio (P > 0.05). Freeze-dried CB powder increased the activity of serum superoxide dismutase, glutathione peroxidase, complement 3, and complement 4. Muscle tyrosine, proline, and total essential amino acids were remarkably increased in the CB 1.04 group (P < 0.05). Propionic acid levels were elevated in the CB 1.04 and CB4.16 groups (P < 0.001). The relative expression of Dorsal, Relish, and Target of Rapamycin (TOR) genes was significantly increased in the CB 1.04 group (P < 0.01). Actinobacteria and Demequina abundance was significantly higher in the CB 1.04 group (P < 0.01). The results of the Vibrio parahaemolyticus challenge test showed the highest cumulative mortality rate (43.33%) in the CB0 group and the lowest cumulative mortality rate (20%) in the CB1.04 group. This study confirmed that freeze-dried CB powder alleviated the negative effects of CPC replacement of fish meal protein in Litopenaeus vannamei, and the optimum additive level was 2.11% (9.71 × 109 CFU/kg) as indicated by binary regression analysis of specific growth ratio.

The potential of glycinin basic peptide derived from soybean as a promising candidate for the natural food additive and preservative: A review

Glycinin basic peptide (GBP) is the basic polypeptide of soybean glycinin that is isolated using cheap and readily available raw materials (soybean meals). GBP can bear high-temperature processing and has good functional properties, such as emulsification and adhesion properties et al. GBP exhibits broad-spectrum antimicrobial activities against Gram-positive and Gram-negative bacteria as well as fungi. Beyond that, GBP shows enormous application potential to improve the quality and extend the shelf life of food products. This review will systematically provide information on the purification, physicochemical and functional properties of GBP. Moreover, the antimicrobial activities and multi-target antimicrobial mechanism of GBP as well as the applications of GBP in different food products are also reviewed and discussed in detail. This review aims to offer valuable insights for the applications of GBP in the food industry as a promising natural food additive and preservative.

siRNA Nanoparticle Dry Powder Formulation with High Transfection Efficiency and Pulmonary Deposition for Acute Lung Injury Treatment

Acute lung injury (ALI) is a severe inflammatory syndrome, which was caused by diverse factors. The COVID-19 pandemic has resulted in a higher mortality rate of these conditions. Currently, effective treatments are lacking. Although siRNA nucleotide-based drugs are promising therapeutic approaches, their poor stability and inability to efficiently reach target cells limit their clinical translation. This study identified a peptide from known cell-penetrating peptides that can form an efficient anti-inflammatory complex with TNF-α siRNA, termed SAR6EW/TNF-α siRNA. This complex can effectively transport TNF-α siRNA into the cytoplasm and achieve potent gene silencing in vitro as well as in vivo. By using lactose and triarginine as coexcipients and optimizing the spray-drying process, a powder was produced with micrometer-scale spherical and porous structures, enhancing aerosol release and lung delivery efficiency. The dry powder formulation and process preserve the stability and integrity of the siRNA. When administered intratracheally to ALI model mice, the complex powder demonstrated specific pulmonary gene silencing activity and significantly reduced inflammation symptoms caused by ALI, suggesting a potential strategy for the clinical therapeutic approach of respiratory diseases.

Long term investigation of formulation buffers to mitigate stability issues of conjugated critical reagents

Stability of conjugated critical reagents supporting ligand binding assays to enable biotherapeutic drug development is a universal concern. Formulation buffer employed for long-term cold storage may be key to mitigate protein aggregation issues. We investigated biophysical and functional attributes of murine mAb and human multispecific drug labeled with biotin, ruthenium, and Alexa fluor 647 frozen at -80 °C in PBS or a protein storage buffer for 3-15 months. Aggregation was observed at 4 months in mAb A-Ru (11.2%) and -Alexa (10%) in PBS followed by precipitation and reduced biological binding at 15 months. Increased aggregation in drug Ru (11.7%, 6 months) and Alexa (6.9%, 15 months) were noted but without impact on performance. There were no observations with biotin labeled reagents.

Histidine as a versatile excipient in the protein-based biopharmaceutical formulations

Adequate stabilization is essential for marketed protein-based biopharmaceutical formulations to withstand the various stresses that can be exerted during the pre- and post-manufacturing processes. Therefore, a suitable choice of excipient is a significant step in the manufacturing of such delicate products. Histidine, an essential amino acid, has been extensively used in protein-based biopharmaceutical formulations. The physicochemical properties of histidine are unique among amino acids and could afford multifaceted benefits to protein-based biopharmaceutical formulations. With a pKa of approximately 6.0 at the side chain, histidine has been primarily used as a buffering agent, especially for pH 5.5-6.5. Additionally, histidine exhibited several affirmative properties similar to those of carbohydrates (e.g., sucrose and trehalose) and could therefore be considered to be an alternative approach to established protein-based formulation strategies. The current review describes the general physicochemical properties of histidine, lists all commercial histidine-containing protein-based biopharmaceutical products, and discusses a brief outline of the existing research focused on the versatile applications of histidine, which can act as a buffering agent, stabilizer, cryo-/lyo-protectant, antioxidant, viscosity reducer, and solubilizing agent. The interaction between histidine and proteins in protein-based biopharmaceutical formulations, such as the Donnan effect during diafiltration of monoclonal antibody solutions and the degradation of polysorbates in histidine buffer, has also been discussed. As the first review of histidine in protein biopharmaceuticals, it helps to deepen our understanding of the opportunities and challenges associated with histidine as an excipient for protein-based biopharmaceutical formulations.

Leucine as a Moisture-Protective Excipient in Spray-Dried Protein/Trehalose Formulation

The incorporation of leucine (Leu), a hydrophobic amino acid, into pharmaceutically relevant particles via spray-drying can improve the physicochemical and particulate properties, stability, and ultimately bioavailability of the final product. More specifically, Leu has been proposed to form a shell on the surface of spray-dried (SD) particles. The aim of this study was to explore the potential of Leu in the SD protein/trehalose (Tre) formulation to control the water uptake and moisture-induced recrystallization of amorphous Tre, using lysozyme (LZM) as a model protein. LZM/Tre (1:1, w/w) was dissolved in water with varied amounts of Leu (0 - 40%, w/w) and processed by spray-drying. The solid form, residual moisture content (RMC), hygroscopicity, and morphology of SD LZM/Tre/Leu powders were evaluated, before and after storage under 22°C/55% RH conditions for 90 and 180 days. The X-ray powder diffraction results showed that Leu was in crystalline form when the amount of Leu in the formulation was at least 20% (w/w). Thermo-gravimetric analysis and scanning electron microscopy results showed that 0%, 5%, and 10% (w/w) Leu formulations led to comparable RMC and raisin-like round particles. In contrast, higher Leu contents resulted in a lower RMC and increased surface corrugation of the SD particles. Dynamic vapor sorption analysis showed that partial recrystallization of amorphous Tre to crystalline Tre·dihydrate occurred in the 0% Leu formulation. However, adding as little as 5% (w/w) Leu inhibited this recrystallization during the water sorption/desorption cycle. In addition, after storage, the formulations with higher Leu contents showed reduced water uptake. Instead of observing recrystallization of amorphous Tre in 0%, 5%, and 10% (w/w) Leu formulations, recrystallization of amorphous Leu was noted in the 5% and 10% (w/w) Leu formulations after storage. In summary, our study demonstrated that the addition of Leu has the potential to reduce water uptake and inhibit moisture-induced recrystallization of amorphous Tre in the SD protein/Tre powder system.

Lyophilizable Stem Cell-Hybrid Liposome with Long-Term Stability and High Targeting Capacity

The hybridization of liposome with stem cell membranes is an emerging technology to prepare the nanovehicle with the capacity of disease-responsive targeting. However, the long-term storage of this hybrid liposome has received limited attention in the literature, which is essential for its potential applicability in the clinic. Therefore, the preservation of long-term activity of stem cell-hybrid liposome using freeze-drying is investigated in the present study. Mesenchymal stem cell-hybrid liposome is synthesized and its feasibility for freeze-drying under different conditions is examined. Results reveal that pre-freezing the hybrid liposome at -20 °C in Tris buffer solution (pH 7.4) containing 10% trehalose can well preserve the liposomal structure for at least three months. Notably, major membrane proteins on the hybrid liposome are protected in this formulation and CXCR4-associated targeting capacity is maintained both in vitro and in vivo. Consequently, the hybrid liposome stored for three months demonstrates a comparable tumor inhibition as the fresh-prepared one. The present study provides the first insights into the long-term storage of stem cell hybrid liposome using lyophilization, which may make an important step forward in enhancing the long-term stability of these promising biomimetic nanovehicle and ease the logistics and the freeze-storage in the potential clinical applications.

Effect of surfactants on lactate dehydrogenase aqueous solutions: A comparative study of poloxamer 188, polysorbate 20 and 80

The effect of three commonly used surfactants, poloxamer 188 (P188), polysorbate 20 and 80 (PS20 and PS80), on the stability of a model protein, lactate dehydrogenase (LDH), was compared in aqueous solutions. In the absence of a surfactant, protein solution revealed a gradual decrease in surface tension as a function of time. The addition of surfactant resulted in a rapid decrease in the surface tension. This suggested that the surface behavior was dictated by the surfactant. PS20 and PS80 were more effective than P188 in preventing LDH adsorption on the solution surface. The advantage of polysorbates over P188 was also evident from the higher LDH tetramer recovery after shaking (room temperature, 30 h), especially when the surfactants were used at concentrations ≤ 0.01% w/v. However, PS20 and PS80 accelerated protein unfolding during quiescent storage at 40 °C. Based on circular dichroism results, polysorbates perturbed the tertiary structure of LDH but not the secondary structure, while P188 did not impact the protein structure and stability. Polysorbates were more effective in stabilizing LDH against mechanical stress (shaking), but their adverse effects on protein conformational stability need to be carefully evaluated.

Impact of Ultrafiltration on the Physicochemical Properties of Bovine Lactoferrin: Insights into Molecular Mass, Surface Morphology, and Elemental Composition

The large-scale isolation of bovine lactoferrin (bLF) typically involves using large amounts of concentrated eluents, which might introduce impurities to the final product. Sometimes, protein pre-concentration is required for the greater accuracy of experimental results. In this research, the supplied bLF sample was subjected to additional ultrafiltration (UF) to eliminate possible small impurities, such as salts and peptides of bLF. Beforehand, the basic characterization of native bLF, including surface-charge properties and the structural sensitivity to the various pH conditions, was performed. The study aimed to evaluate the difference in molecular mass, primary structure, surface morphology, and elemental composition of the protein before and after UF. The research was provided by application of spectroscopic, spectrometric, electrophoretic, and microscopic techniques. The evident changes in the surface morphology of bLF were observed after UF, while the molecular masses of both proteins were comparable. According to MALDI-TOF/MS results, UF had a positive impact on the bLF sample representation, improving the identification parameters, such as sequence coverage and intensity coverage.

Trimethylamine N-oxide (TMAO) doubly locks the hydrophobic core and surfaces of protein against desiccation stress

Interactions between proteins and osmolytes are ubiquitous within cells, assisting in response to environmental stresses. However, our understanding of protein-osmolyte interactions underlying desiccation tolerance is limited. Here, we employ solid-state NMR (ssNMR) to derive information about protein conformation and site-specific interactions between the model protein, SH3, and the osmolyte trimethylamine N-oxide (TMAO). The data show that SH3-TMAO interactions maintain key structured regions during desiccation and facilitate reversion to the protein's native state once desiccation stress is even slightly relieved. We identify 10 types of residues at 28 sites involved in the SH3-TMAO interactions. These sites comprise hydrophobic, positively charged, and aromatic amino acids located in SH3's hydrophobic core and surface clusters. TMAO locks both the hydrophobic core and surface clusters through its zwitterionic and trimethyl ends. This double locking is responsible for desiccation tolerance and differs from ideas based on exclusion, vitrification, and water replacement. ssNMR is a powerful tool for deepening our understanding of extremely weak protein-osmolyte interactions and providing insight into the evolutionary mechanism of environmental tolerance.

The role of fat content in coconut milk: Stability and digestive properties

The fat in coconut milk contributes to unique flavour, while increasing fat content affects stability of the coconut milk. In this study, coconut water and fat were separated, recombined, and homogenized to obtain coconut milk with different fat contents (0-20 %). Emulsifying properties, stability, and digestibility of coconut milk with different fat contents were comprehensively evaluated. The results showed that as the fat content increased from 0 to 20 %, the droplet size increased from 2.18 to 4.70 μm and the viscosity showed an increasing trend. During storage and freeze-thaw, coconut milk with 5 % and 10 % fat content showed excellent stability. In addition, coconut milk with 10 % fat content had superior fat digestibility, which was related to high affinity of pancrelipase. In short, this study revealed that fat content below 10 % can withstand environmental factors such as storage, lipid oxidation, and freeze-thaw, which can be accurately developed as coconut milk products.

Molecular Insights into the Conformational and Binding Behaviors of Human Serum Albumin Induced by Surface-Active Ionic Liquids

Extensive research has been carried out to investigate the stability and function of human serum albumin (HSA) when exposed to surface-active ionic liquids (SAILs) with different head groups (imidazolium, morpholinium, and pyridinium) and alkyl chain lengths (ranging from decyl to tetradecyl). Analysis of the protein fluorescence spectra indicates noticeable changes in the secondary structure of HSA with varying concentrations of all SAILs tested. Helicity calculations based on the Fourier transform infrared (FTIR) data show that HSA becomes more organized at the micellar concentration of SAILs, leading to an increased protein activity at this level. Small-angle neutron scattering (SANS) data confirm the formation of a bead-necklace structure between the SAILs and HSA. Atomistic molecular dynamics (MD) simulation results identify several hotspots on the protein surface for interaction with SAIL, which results in the modulation of protein conformational fluctuation and stability. Furthermore, fluorescence resonance energy transfer (FRET) experiments with the intramolecular charge transfer (ICT) probe trans-ethyl p-(dimethylamino) cinnamate (EDAC) demonstrate that higher alkyl chain lengths and SAIL concentrations result in a significantly increased energy transfer efficiency. The findings of this study provide a detailed molecular-level understanding of how the protein structure and function are affected by the presence of SAILs, with potential implications for a wide range of applications involving protein-SAIL composite systems.

Impact of pilot-scale microfluidization on soybean protein structure in powder and solution

The effect of microfluidization treatment on the primary, secondary, and tertiary structure of soybean protein isolate (SPI) was investigated. The samples were treated with and without controlling the temperature and circulated in the system 1, 3, and 5 times at high pressure (137 MPa). Then, the treated samples were freeze-dried and reconstituted in water to check the impact of the microfluidization on two different states: powder and solution. Regarding the primary structure, the SDS-PAGE analysis under reducing conditions showed that the protein bands remained unchanged when exposed to microfluidization treatment. When the temperature was controlled for the samples in their powder state, a significant decrease in the quantities of β-sheet and random coil and a slight reduction in α-helix content was noticed. The observed decrease in β-sheet and the increase in β-turns in treated samples indicated that microfluidization may lead to protein unfolding, opening the hydrophobic regions. Additionally, a lower amount of α-helix suggests a higher protein flexibility. After reconstitution in water, a significant difference was observed only in α-helix, β-sheet and β-turn. Related to the tertiary structure, microfluidization increases the surface hydrophobicity. Among all the conditions tested, the samples where the temperature is controlled seem the most suitable.

Comparison of Sucrose and Trehalose for Protein Stabilization Using Differential Scanning Calorimetry

The disaccharide trehalose is generally acknowledged as a superior stabilizer of proteins and other biomolecules in aqueous environments. Despite many theories aiming to explain this, the stabilization mechanism is still far from being fully understood. This study compares the stabilizing properties of trehalose with those of the structurally similar disaccharide sucrose. The stability has been evaluated for the two proteins, lysozyme and myoglobin, at both low and high temperatures by determining the glass transition temperature, Tg, and the denaturation temperature, Tden. The results show that the sucrose-containing samples exhibit higher Tden than the corresponding trehalose-containing samples, particularly at low water contents. The better stabilizing effect of sucrose at high temperatures may be explained by the fact that sucrose, to a greater extent, binds directly to the protein surface compared to trehalose. Both sugars show Tden elevation with an increasing sugar-to-protein ratio, which allows for a more complete sugar shell around the protein molecules. Finally, no synergistic effects were found by combining trehalose and sucrose. Conclusively, the exact mechanism of protein stabilization may vary with the temperature, as influenced by temperature-dependent interactions between the protein, sugar, and water. This variability can make trehalose to a superior stabilizer under some conditions and sucrose under others.

Dual Functionality of Poloxamer 188 in Freeze-Dried Protein Formulations: A Stabilizer in Frozen Solutions and a Bulking Agent in Lyophiles

Poloxamer 188 (P188) was hypothesized to be a dual functional excipient, (i) a stabilizer in frozen solution to prevent ice-surface-induced protein destabilization and (ii) a bulking agent to provide elegant lyophiles. Based on X-ray diffractometry and differential scanning calorimetry, sucrose, in a concentration-dependent manner, inhibited P188 crystallization during freeze-drying, while trehalose had no such effect. The recovery of lactate dehydrogenase (LDH), the model protein, was evaluated after reconstitution. While low LDH recovery (∼60%) was observed in the lyophiles prepared with P188, the addition of sugar improved the activity recovery to >85%. The secondary structure of LDH in the freeze-dried samples was assessed using infrared spectroscopy, and only moderate structural changes were observed in the lyophiles formulated with P188 and sugar. Thus, P188 can be a promising dual functional excipient in freeze-dried protein formulations. However, P188 alone does not function as a lyoprotectant and needs to be used in combination with a sugar.

Combined effect of SAR-endolysin LysKpV475 with polymyxin B and Salmonella bacteriophage phSE-5

Endolysins are bacteriophage (or phage)-encoded enzymes that catalyse the peptidoglycan breakdown in the bacterial cell wall. The exogenous action of recombinant phage endolysins against Gram-positive organisms has been extensively studied. However, the outer membrane acts as a physical barrier when considering the use of recombinant endolysins to combat Gram-negative bacteria. This study aimed to evaluate the antimicrobial activity of the SAR-endolysin LysKpV475 against Gram-negative bacteria as single or combined therapies, using an outer membrane permeabilizer (polymyxin B) and a phage, free or immobilized in a pullulan matrix. In the first step, the endolysin LysKpV475 in solution, alone and combined with polymyxin B, was tested in vitro and in vivo against ten Gram-negative bacteria, including highly virulent strains and multidrug-resistant isolates. In the second step, the lyophilized LysKpV475 endolysin was combined with the phage phSE-5 and investigated, free or immobilized in a pullulan matrix, against Salmonella enterica subsp. enterica serovar Typhimurium ATCC 13311. The bacteriostatic action of purified LysKpV475 varied between 8.125 μg ml-1 against Pseudomonas aeruginosa ATCC 27853, 16.25 μg ml-1 against S. enterica Typhimurium ATCC 13311, and 32.50 μg ml-1 against Klebsiella pneumoniae ATCC BAA-2146 and Enterobacter cloacae P2224. LysKpV475 showed bactericidal activity only for P. aeruginosa ATCC 27853 (32.50 μg ml-1) and P. aeruginosa P2307 (65.00 μg ml-1) at the tested concentrations. The effect of the LysKpV475 combined with polymyxin B increased against K. pneumoniae ATCC BAA-2146 [fractional inhibitory concentration index (FICI) 0.34; a value lower than 1.0 indicates an additive/combined effect] and S. enterica Typhimurium ATCC 13311 (FICI 0.93). A synergistic effect against S. enterica Typhimurium was also observed when the lyophilized LysKpV475 at ⅔ MIC was combined with the phage phSE-5 (m.o.i. of 100). The lyophilized LysKpV475 immobilized in a pullulan matrix maintained a significant Salmonella reduction of 2 logs after 6 h of treatment. These results demonstrate the potential of SAR-endolysins, alone or in combination with other treatments, in the free form or immobilized in solid matrices, which paves the way for their application in different areas, such as in biocontrol at the food processing stage, biosanitation of food contact surfaces and biopreservation of processed food in active food packing.

Effects of freezing and drying programs on IgY aggregation and activity during microwave freeze-drying: Protective effects and interactions of trehalose and mannitol

The acquisition of high quality lyophilized IgY products, characterized by an aesthetically pleasing visage, heightened stability, and a marked preservation of activity, constitutes an indispensable pursuit in augmenting the safety and pragmatic utility of IgY. Within this context, an exploration was undertaken to investigate an innovative modality encompassing microwave freeze-drying (MFD) as a preparatory methodology of IgY. Morphological assessments revealed that both cryogenic freezing and subsequent MFD procedures resulted in aggregation of IgY, with the deleterious influence posed by the MFD phase transcending that of the freezing phase. The composite protective agent comprised of trehalose and mannitol engendered a safeguarding effect on the structural integrity of IgY, thereby attenuating reducing aggregation between IgY during the freeze-drying process. Enzyme-linked immunosorbent assay (ELISA) outcomes demonstrated a discernible correlation between IgY aggregation and a notable reduction in its binding affinity towards the pertinent antigen. Comparative analysis vis-à-vis the control sample delineated that when the trehalose-to-mannitol ratio was upheld at 1:3, a two-fold outcome was achieved: a mitigation of the collapse susceptibility within the final product as well as a deterrence of IgY agglomeration, concomitant with an elevated preservation rate of active antibodies (78.57 %).

Removal of plant endogenous proteins from tobacco leaf extract by freeze-thaw treatment for purification of recombinant proteins

Plants are useful as a low-cost source for producing biopharmaceutical proteins. A significant hurdle in the production of recombinant proteins in plants, however, is the complicated process of removing plant-derived components. Removing endogenous plant proteins, including ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), a major photosynthetic plant enzyme that catalyzes photosynthesis through carboxylation and oxygenation, is important for the purification of recombinant plant proteins. In particular, RuBisCO accounts for 50% of the soluble leaf protein; thus, the removal of RuBisCO is critical for the purification of recombinant proteins from plant materials. An effective conventional method, known as freeze-thaw treatment, was developed for the removal of RuBisCO from Nicotiana benthamiana, which expresses recombinant green fluorescent protein (GFP). Crude extracts or supernatants were frozen at - 30 °C. Upon thawing, most of the RuBisCO was precipitated by centrifugation without significant inactivation and/or yield reduction of GFP. Based on the proteomics analysis, using this method, RuBisCO large and small subunits were reduced to approximately 10% and 20% of those of the unfrozen supernatant solutions, respectively, without the need for specific reagents or equipment. The proteomic analysis also revealed that many ribosomal proteins were removed from the extracts. This method improves the purification process of recombinant proteins from plant materials. Prolonged freezing damaged recombinant β-glucuronidase (GUS), suggesting that the applicability of this treatment should be carefully considered for each recombinant protein.

Screening and Stability Evaluation of Freeze-Dried Protective Agents for a Live Recombinant Pseudorabies Virus Vaccine

Infection of pigs with the pseudorabies virus (PRV) causes significant economic losses in the pig industry. Immunization with live vaccines is a crucial aspect in the prevention of pseudorabies in swine. The TK/gE/gI/11k/28k deleted pseudorabies vaccine is a promising alternative for the eradication of epidemic pseudorabies mutant strains. This study optimized the lyophilization of a heat-resistant PRV vaccine to enhance the quality of a live vaccine against the recombinant PRV rHN1201TK-/gE-/gI-/11k-/28k-. The A4 freeze-dried protective formulation against PRV was developed by comparing the reduction in virus titer after lyophilization and after seven days of storage at 37 °C. The formulation contains 1% gelatin, 5% trehalose, 0.5% poly-vinylpyrimidine (PVP), 0.5% thiourea, and 1% sorbitol. The A4 freeze-dried vaccine demonstrated superior protection and thermal stability. It experienced a freeze-dried loss of 0.31 Lg post-freeze-drying and a heat loss of 0.42 Lg after being stored at a temperature of 37 °C for 7 consecutive days. The A4 freeze-dried vaccine was characterized through XRD, FTIR, and SEM analyses, which showed that it possessed an amorphous structure with a consistent porous interior. The trehalose component of the vaccine formed stable hydrogen bonds with the virus. Long-term and accelerated stability studies were also conducted. The A4 vaccine maintained viral titer losses of less than 1.0 Lg when exposed to 25 °C for 90 days, 37 °C for 28 days, and 45 °C for 7 days. The A4 vaccine had a titer loss of 0.3 Lg after storage at 2-8 °C for 24 months, and a predicted shelf life of 6.61 years at 2-8 °C using the Arrhenius equation. The A4 freeze-dried vaccine elicited no side effects when used to immunize piglets and produced specific antibodies. This study provides theoretical references and technical support to improve the thermal stability of recombinant PRV rHN1201TK-/gE-/gI-/11k-/28k- vaccines.

Effects of Amino Acid Additives on Protein Stability during Electrothermal Supercharging in ESI-MS

The surprising formation of highly charged protein ions from aqueous ammonium bicarbonate solution is a fascinating phenomenon referred to as electrothermal supercharging (ETS). Although the precise mechanism involved is not clearly understood, previous studies predominantly suggest that ETS is due to native protein destabilization in the presence of bicarbonate anion inside the electrospray ionization droplets under high temperatures and spray voltages. To evaluate existing hypotheses surrounding the underlying mechanism of ETS, the effects of several additives on protein charging under ETS conditions were investigated. The changes in the protein charge state distributions were compared by measuring the ratios between the intensities of highest intensity charge states of native and unfolded protein envelopes and shifts in the lowest and highest observed charge states. This study demonstrated that source temperature plays a more important role in ETS compared to spray voltage, especially when using a nebulized microelectrospray ionization source. Moreover, the effect of amino acids on ETS were generally in good agreement with the extensive literature available on the stabilization or destabilization of proteins by these additives in bulk solution. Among the natural amino acids, protein supercharging was significantly reduced by proline and glycine; however, imidazole provided the highest degree of noncovalent complex stabilization against ETS, outperforming the amino acids. Overall, our study shows that the simple addition of stabilizing reagents such as proline and imidazole can reduce the extent of apparent protein unfolding and supercharging in ammonium bicarbonate solution and provide evidence against the roles of charge depletion and thermal unfolding during ETS.

Influence of water and trehalose on α- and β-relaxation of freeze-dried lysozyme formulations

Molecular mobility in form of alpha and beta relaxations is considered crucial for characterization of amorphous lyophilizates and reflected in the transition temperatures Tgα and Tgβ. Based on an overview of applied methods to study beta relaxations, Dynamic Mechanical analysis was used to measure Tgα and Tgβ in amorphous freeze-dried samples. Lysozyme and trehalose as well as their mixtures in varying ratios were investigated. Three different residual moisture levels, ranging from roughly 0.5-7 % (w/w), were prepared via equilibration of the freeze-dried samples. Known plasticising effects of water on Tgα were confirmed, also via differential scanning calorimetry. In addition and contrary to expectations, an influence of water on the Tgβ also was observed. On the other hand, an increasing amount of trehalose lowered Tgα but increased Tgβ showing that Tgα and Tgβ are not paired. The findings were interpreted with regard to their underlying molecular mechanisms and a correlation with the known influences of water and trehalose on stability. The results provide encouraging hints for future stability studies of freeze-dried protein formulations, which are urgently needed, not least for reasons of sustainability.

Stabilization effects of saccharides in protein formulations: A review of sucrose, trehalose, cyclodextrins and dextrans

Saccharides are a popular group of stabilizers in liquid, frozen and freeze dried protein formulations. The current work reviewed the stabilization mechanisms of three groups of saccharides: (i) Disaccharides, specifically sucrose and trehalose; (ii) cyclodextrins (CDs), a class of cyclic oligosaccharides; and (iii) dextrans, a class of polysaccharides. Compared to sucrose, trehalose exhibits a more pronounced preferential exclusion effect in liquid protein formulations, due to its stronger interaction with water molecules. However, trehalose obtains higher phase separation and crystallization propensity in frozen solutions, resulting in the loss of its stabilization function. In lyophilized formulations, sucrose has a higher crystallization propensity. Besides, its glass matrix is less homogeneous than that of trehalose, thus undermining its lyoprotectant function. Nevertheless, the hygroscopic nature of trehalose may result in high water absorption upon storage. Among all the CDs, the β form is believed to have stronger interactions with proteins than the α- and γ-CDs. However, the stabilization effect, brought about by CD-protein interactions, is case-by-case - in some examples, such interactions can promote protein destabilization. The stabilization effect of hydroxypropyl-β-cyclodextrin (HPβCD) has been extensively studied. Due to its amphiphilic nature, it can act as a surface-active agent in preventing interfacial stresses. Besides, it is a dual functional excipient in freeze dried formulations, acting as an amorphous bulking agent and lyoprotectant. Finally, dextrans, when combined with sucrose or trehalose, can be used to produce stable freeze dried protein formulations. A strong stabilization effect can be realized by low molecular weight dextrans. However, the terminal glucose in dextrans yields protein glycation, which warrants extra caution during formulation development.

Stabilization challenges and aggregation in protein-based therapeutics in the pharmaceutical industry

Protein-based therapeutics have revolutionized the pharmaceutical industry and become vital components in the development of future therapeutics. They offer several advantages over traditional small molecule drugs, including high affinity, potency and specificity, while demonstrating low toxicity and minimal adverse effects. However, the development and manufacturing processes of protein-based therapeutics presents challenges related to protein folding, purification, stability and immunogenicity that should be addressed. These proteins, like other biological molecules, are prone to chemical and physical instabilities. The stability of protein-based drugs throughout the entire manufacturing, storage and delivery process is essential. The occurrence of structural instability resulting from misfolding, unfolding, and modifications, as well as aggregation, poses a significant risk to the efficacy of these drugs, overshadowing their promising attributes. Gaining insight into structural alterations caused by aggregation and their impact on immunogenicity is vital for the advancement and refinement of protein therapeutics. Hence, in this review, we have discussed some features of protein aggregation during production, formulation and storage as well as stabilization strategies in protein engineering and computational methods to prevent aggregation.

Solid-State NMR Spectroscopy to Probe State and Phase Transitions in Frozen Solutions

Freezing is commonly encountered during the processing and storage of biomacromolecule products. Therefore, understanding the phase and state transitions in pharmaceutical frozen solutions is crucial for the rational development of biopharmaceuticals. Solid-state nuclear magnetic resonance spectroscopy (ssNMR) was used to analyze solutions containing sodium phosphate buffer, histidine, and trehalose. Upon freezing, crystallization of disodium phosphate hydrogen dodecahydrate (Na2HPO4·12H2O, DPDH) and histidine was identified using 31P and 13C ssNMR, respectively, and confirmed by synchrotron X-ray diffractometry (SXRD). Using histidine as a molecular probe and based on the chemical shifts of atoms of interest, the pH of the freeze concentrate was measured. The unfrozen water content in freeze concentrates was quantified by 1H single pulse experiments. 13C-insensitive nuclei enhancement by polarization transfer (INEPT) and cross-polarization (CP) experiments were used as orthogonal tools to characterize the solutes in a "mobile" and a more "solid-like" state in the freeze-concentrated solutions, respectively. The above analyses were applied to a commercial monoclonal antibody (mAb) formulation of dupilumab. This work further establishes ssNMR spectroscopy as a highly capable biophysical tool to investigate the attributes of biopharmaceuticals and thereby provide insights into process optimization and formulation development.

Vaporized Hydrogen Peroxide Sterilization in the Production of Protein Therapeutics: Uptake and Effects on Product Quality

The aseptic filling of drug products is carried out in pharmaceutical isolators that have been sterilized. A commonly used method for achieving a high level of sterility assurance is vaporized hydrogen peroxide (VHP) sterilization, which is favorable to other methods, such as ethylene oxide sterilization, due to its low cycle times and nontoxic residuals. While VHP cycles are often employed to create a sterile environment within an isolator, they can leave residual levels of hydrogen peroxide behind that can enter the product during fill-finish operations. Due to the oxidizing potential of hydrogen peroxide and the multiple possible sources of uptake along filling lines, the extent of the potential impact on product quality needs to be understood during pharmaceutical development. Herein, different factors affecting hydrogen peroxide uptake, points of entry along the filling line, and possible impacts on product quality are reviewed.

Application of Formulation Principles to Stability Issues Encountered During Processing, Manufacturing, and Storage of Drug Substance and Drug Product Protein Therapeutics

The field of formulation and stabilization of protein therapeutics has become rather extensive. However, most of the focus has been on stabilization of the final drug product. Yet, proteins experience stress and degradation through the manufacturing process, starting with fermentaition. This review describes how formulation principles can be applied to stabilize biopharmaceutical proteins during bioprocessing and manufacturing, considering each unit operation involved in prepration of the drug substance. In addition, the impact of the container on stabilty is discussed as well.

Solidification and oral delivery of biologics to the colon- A review

The oral delivery of biologics such as therapeutic proteins, peptides and oligonucleotides for the treatment of colon related diseases has been the focus of increasing attention over the last years. However, the major disadvantage of these macromolecules is their degradation propensity in liquid state which can lead to the undesirable and complete loss of function. Therefore, to increase the stability of the biologic and reduce their degradation propensity, formulation techniques such as solidification can be performed to obtain a stable solid dosage form for oral administration. Due to their fragility, stress exerted on the biologic during solidification has to be reduced with the incorporation of stabilizing excipients into the formulation. This review focuses on the state-of-the-art solidification techniques required to obtain a solid dosage form for the oral delivery of biologics to the colon and the use of suitable excipients for adequate stabilization upon solidification. The solidifying processes discussed within this review are spray drying, freeze drying, bead coating and also other techniques such as spray freeze drying, electro spraying, vacuum- and supercritical fluid drying. Further, the colon as site of absorption in both healthy and diseased state is critically reviewed and possible oral delivery systems for biologics are discussed.

Role of Poloxamer 188 in Preventing Ice-Surface-Induced Protein Destabilization during Freeze-Thawing

The phase behavior of poloxamer 188 (P188) in aqueous solutions, characterized by differential scanning calorimetry (DSC) and synchrotron X-ray diffractometry, revealed solute crystallization during both freezing and thawing. Sucrose and trehalose inhibited P188 crystallization during freeze-thawing (FT). While trehalose inhibited P188 crystallization only during cooling, sucrose completely suppressed P188 crystallization during both cooling and heating. Lactate dehydrogenase (LDH) served as a model protein to evaluate the stabilizing effect of P188. The ability of P188, over a concentration range of 0.003-0.800% w/v, to prevent LDH (10 μg/mL) destabilization was evaluated. After five FT cycles, the aggregation behavior (by dynamic light scattering) and activity recovery were evaluated. While LDH alone was sensitive to interfacial stress, P188 at concentrations of ≥0.100% w/v stabilized the protein. However, as the surfactant concentration decreased, protein aggregation after FT increased. The addition of sugar (1.0% w/v; sucrose or trehalose) improved the stabilizing function of P188 at lower concentrations (≤0.010% w/v), possibly due to the inhibition of surfactant crystallization. Based on a comparison with the stabilization effect of polysorbate (both 20 and 80), it was evident that P188 could be a promising alternative surfactant in frozen protein formulations. However, when the surfactant concentration is low, the potential for P188 crystallization and the consequent compromise in its functionality warrant careful consideration.

Investigating freezing-induced acidity changes in citrate buffers

Citrate buffers are commonly utilized in the field of biomolecule stabilization. We investigate their applicability in the frozen state within a range of initial pHs (2.5 to 8.0) and concentrations (0.02 to 0.60 M). Citrate buffer solutions subjected to various cooling and heating temperatures are examined in terms of the freezing-induced acidity changes, revealing that citrate buffers acidify upon cooling. The acidity is assessed with sulfonephthalein molecular probes frozen in the samples. Optical cryomicroscopy combined with differential scanning calorimetry was employed to investigate the causes of the observed acidity changes. The buffers partly crystallize and partly vitrify in the ice matrix; these processes influence the resulting pH and allow designing the optimal storage temperatures in the frozen state. The freezing-induced acidification apparently depends on the buffer concentration; at each pH, we suggest pertinent concentration, at which freezing causes minimal acidification.

Spectroscopic analysis of recombinant human growth hormone in the presence of sucrose and trehalose

Recombinant human growth hormone (rhGH) is a therapeutic protein, associated with various human diseases, such as growth hormone deficiency. One of the interesting issues in the formulation of therapeutic proteins is excipients like disaccharides. In the current study, we try to compare the effect of sucrose and trehalose on the structure of rhGH in the liquid state at 25°C and 55°C. We use spectroscopic techniques including intrinsic and extrinsic fluorescence, Fourier-transform infrared (FTIR), circular dichroism (CD), dynamic light scattering (DLS), and time-resolved fluorescence. FTIR shows a slight change in the secondary structure of rhGH in presence of the sugars as sucrose is more effective than trehalose. Fluorescence investigations also confirm the enhancements of folding of rhGH and fluorescein isothiocyanate (FITC)-rhGH in presence of sucrose (1.5-fold more than trehalose). Also, we studied sucrose's effect on the rete of aggregation of rhGH using spectroscopy of Congo red, and fluorescence imaging of thioflavin T (ThT)-treated samples. It can be suggested that sucrose facilitates the amyloid formation of rhGH during 20 days of incubation at 37°C. This study will help to understand the growth hormone structural behavior in the liquid state in the presence of sucrose and trehalose in vitro.

Study of Oncolytic Virus Preservation and Formulation

In recent years, oncolytic viruses (OVs) have emerged as an effective means of treating cancer. OVs have multiple oncotherapeutic functions including specifically infecting and lysing tumor cells, initiating immune cell death, attacking and destroying tumor angiogenesis and triggering a broad bystander effect. Oncolytic viruses have been used in clinical trials and clinical treatment as drugs for cancer therapy, and as a result, oncolytic viruses are required to have long-term storage stability for clinical use. In the clinical application of oncolytic viruses, formulation design plays a decisive role in the stability of the virus. Therefore, this paper reviews the degradation factors and their degradation mechanisms (pH, thermal stress, freeze-thaw damage, surface adsorption, oxidation, etc.) faced by oncolytic viruses during storage, and it discusses how to rationally add excipients for the degradation mechanisms to achieve the purpose of maintaining the long-term stability of oncolytic viral activity. Finally, the formulation strategies for the long-term formulation stability of oncolytic viruses are discussed in terms of buffers, permeation agents, cryoprotectants, surfactants, free radical scavengers, and bulking agent based on virus degradation mechanisms.

Enabling Efficient Design of Biological Formulations Through Advanced Characterization

The present review summarizes the use of differential scanning calorimetry (DSC) and scattering techniques in the context of protein formulation design and characterization. The scattering techniques include wide angle X-ray diffractometry (XRD), small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). While DSC is valuable for understanding thermal behavior of the excipients, XRD provides critical information about physical state of solutes during freezing, annealing and in the final lyophile. However, as these techniques lack the sensitivity to detect biomolecule-related transitions, complementary characterization techniques such as small-angle scattering can provide valuable insights.

Accelerating therapeutic protein design with computational approaches toward the clinical stage

Therapeutic protein, represented by antibodies, is of increasing interest in human medicine. However, clinical translation of therapeutic protein is still largely hindered by different aspects of developability, including affinity and selectivity, stability and aggregation prevention, solubility and viscosity reduction, and deimmunization. Conventional optimization of the developability with widely used methods, like display technologies and library screening approaches, is a time and cost-intensive endeavor, and the efficiency in finding suitable solutions is still not enough to meet clinical needs. In recent years, the accelerated advancement of computational methodologies has ushered in a transformative era in the field of therapeutic protein design. Owing to their remarkable capabilities in feature extraction and modeling, the integration of cutting-edge computational strategies with conventional techniques presents a promising avenue to accelerate the progression of therapeutic protein design and optimization toward clinical implementation. Here, we compared the differences between therapeutic protein and small molecules in developability and provided an overview of the computational approaches applicable to the design or optimization of therapeutic protein in several developability issues.

Thermal stability of exenatide encapsulated in stratified dissolving microneedles during storage

As low-temperature storage and transportation of peptides require high costs, improving the dosage form of peptides can reduce costs. We developed a thermostable and fast-releasing stratified dissolving microneedle (SDMN) system for delivering exenatide (EXT) to patients with type 2 diabetes. Among the tested polymers, dextran and polyvinyl alcohol (PVA) were the best at stabilizing EXT under high-temperature storage for 9 weeks. The two polymers possess a relatively high glass transition temperature (T_g) and weak hydrogen bonding between PVA and EXT. Additionally, zinc sulfate (ZnSO₄) had a stabilizing effect on EXT among the selected stabilizers, suggesting that EXT formed a dimer after coordination with zinc ions (Zn²⁺). In addition, the denaturation temperature (T_m) of EXT was increased by adding ZnSO₄, thus stabilizing EXT. Accordingly, SDMNs consisting of a tip layer (dextran encapsulating the Zn²⁺-EXT complex) and a base layer (PVA) were fabricated. Within 2 min of implantation, the EXT loaded on the patch was quickly released into the skin. Transdermal pharmacokinetics studies showed that manufactured SDMNs generated comparable efficacy to subcutaneous injection. Significantly, the remaining EXT amount was not significantly different under storage at 40 °C and -20 °C for 3 months, supporting that the SDMN system had excellent delivery efficiency and stability, thus reducing the dependence on the cold chain.

Potential of Good's buffers to inhibit denaturation of myofibrillar protein upon freezing

The current systematic study sought to examine the potential use of three Good's buffers (MES, MOPS and HEPES) in inhibiting myofibrillar protein (MFP) denaturation induced by acidity changes. The highest degree of acidity variation was found in the center and bottom of large bottles due to the freeze-concentration effect. Good's buffer tended to basify during freezing, and it could prevent the crystallization of sodium phosphate (Na-P) buffer. Acidification upon freezing Na-P disrupted the natural conformation of MFP and induced the formation of large proteins aggregates with tight packing. The 15 mM MES, 20 mM MOPS, and 30 mM HEPES were respectively added to neutralize the strong acidity drop induced by freezing 20 mM Na-P, and all of them significantly improved the stability of the MFP conformation (P < 0.05). This work is not only critical to meet the growing demand for protein, but also groundbreaking for broadening the applicability of Good's buffers in the food industry.

Development of the phage lysin-loaded liposomes as preservatives for live clams

Exogenous applications of phage lysins against Vibrio parahaemolyticus (V. parahaemolyticus) are a challenge due to the gram-negative bacteria outer membrane barrier. This study aimed to improve the antibacterial effect of V. parahaemolyticus phage lysin Lysqdvp001 (Lys), the best-characterized lysin with lytic activity against multiple species of Vibrios, by using liposome delivery. Various kinds of Lys-loaded liposome (Lys-lip) systems were designed and tested. The antibacterial activities of cationic guar gum (CGG) containing liposomes were much higher than the other liposomes, causing >5 log₁₀CFU/mL of reductions of V. parahaemolyticus in buffer and severely damaging the bacterial cell structure. Moreover, some CGG liposome formulations retained high antibacterial effect after both 60-80 °C heat treatments and freeze-drying. Besides, the most stable liposome formulation killed 99 % of V. parahaemolyticus in the seawater with live clams, and its depuration rate against the bacterial contaminated clams also reached 99 %.

Mannitol as an Excipient for Lyophilized Injectable Formulations

The review summarizes the current state of knowledge of mannitol as an excipient in lyophilized injectable small and large molecule formulations. When compared with glycine, the physicochemical properties of mannitol make it a desirable and preferred bulking agent. Though mannitol is a popular bulking agent in freeze-dried formulations, its use may pose certain challenges such as vial breakage or its existence as a metastable crystalline hemihydrate in the final cake, necessitating appropriate mitigation strategies. The understanding of the phase behavior of mannitol in aqueous systems, during the various stages of freeze-drying, can be critical for the optimization of freeze-drying cycle parameters in multi-component formulations. Finally, using a decision tree as a guiding tool, we demonstrate the use of orthogonal techniques for attaining a stable and cost-effective lyophilized drug product containing mannitol.

Professor Raj Suryanarayanan: Scientist, Educator, Mentor, Family Man and Giant in Pharmaceutical Research

This special edition of the Journal of Pharmaceutical Sciences is dedicated to Professor Raj Suryanarayanan (Professor and William & Mildred Peters Endowed Chair, University of Minnesota, School of Pharmacy) and honors his extensive and distinguished career as a scientist, educator and mentor. The goal of this commentary is to provide an overview of Professor Suryanarayanan's noteworthy career path and summarize his key research contributions. The commentary concludes with the personal summaries by guest editors.

Dodecenylsuccinic anhydride-modified oxalate decarboxylase loaded with magnetic nano-Fe3O4@SiO2 for demulsification of oil-in-water emulsions

The inability to demulsify oil-in-water emulsions via green and efficient processes is a challenging problem in many industrial processes. As a novel biodemulsifier, protein demulsifiers display excellent dispersibility and stability, but their demulsification mechanisms are not clear, which severely restricts their large-scale production and application. In this study, the demulsification mechanism of the high-efficiency protein biodemulsifier oxalate decarboxylase (Bacm OxdC), which is secreted by the Bacillus mojavensis XH1 strain, for an oil-in-water emulsion was analyzed. The results showed that Bacm OxdC was spontaneously adsorbed at the oil-water interface and turned its hydrophobic amino acids outward to increase its hydrophobicity and break the emulsified system. Furthermore, it effectively reduced the oil-water interfacial tension and interfacial film strength, thereby reducing the oil-water interfacial energy and finally enabling demulsification. To further improve the demulsification efficiency and reusability, Fe₃O₄@SiO₂@OxdC-DDSA was prepared. This method provided a magnetic response for Bacm OxdC and enabled efficient demulsification. The demulsification rate of Fe₃O₄@SiO₂@OxdC-DDSA reached 98.1% at 24 h, which was 30.7% higher than that of the original Bacm OxdC. After three cycles, the demulsification rate still reached 89.3%, proving it has excellent recyclability. This work is the first study on the demulsification mechanism of protein biodemulsifiers and provides useful insights into the demulsification mechanism of biodemulsifiers for oil-in-water emulsions. In addition, a promising high-efficiency modification technique for protein biodemulsifiers was proposed, which provided information for the development of biodemulsifiers for oil-water separation.

Freeze-drying for the preservation of immunoengineering products

Immunoengineering technologies harness the power of immune system modulators such as monoclonal antibodies, cytokines, and vaccines to treat myriad diseases. Immunoengineering innovations have showed great promise in various practices including oncology, infectious disease, autoimmune diseases, and transplantation. Despite the countless successes, the majority of immunoengineering products contain active moieties that are prone to instability. The current review aims to feature freeze-drying as a robust and scalable solution to the inherent stability challenges in immunoengineering products by preventing the active moiety from degradation. Furthermore, this review describes the stability issues related to immunoengineering products and the utility of the lyophilization process to preserve the integrity and efficacy of immunoengineering tools ranging from biologics to nanoparticle-based vaccines. The concept of the freeze-drying process is described highlighting the quality by design (QbD) for robust process optimization. Case studies of lyophilized immunoengineering technologies and relevant clinical studies using immunoengineering products are discussed.