Everything below concerns Sublimation. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2025-09-10. Where a claim depends on a specific study, the study is described rather than over-claimed.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
The process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Industries use lyophilization for pharmaceuticals, biological products, and food preservation. In the pharmaceutical sector, it extends the shelf life of injectable drugs, vaccines, and proteins that are unstable in aqueous solution. Food manufacturers apply freeze-drying to coffee, fruits, and ready meals to retain flavor and texture. The process is energy-intensive and requires specialized equipment, which limits its use to high-value products. Ongoing research examines how formulation and process parameters affect the quality of the final dried product.
Lyophilization, also known as freeze-drying, is a process that removes water from a material by freezing it and then reducing pressure to allow ice to sublimate directly into vapor. The method begins with a freezing step that solidifies the water content. Next, primary drying lowers the pressure below the triple point of water, enabling sublimation without passing through a liquid phase. A final secondary drying step removes bound water through desorption. This sequence produces a dry, porous cake that can be reconstituted later.
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
The low pressure used during drying allows water vapor to move from the ice surface to a cold condenser. Energy supplied as heat drives sublimation but must stay below the collapse temperature of the frozen matrix. If the product becomes too warm, the frozen structure may soften or melt, reducing pore formation and slowing drying. Formulations often include bulking agents, stabilizers, or buffers to support a rigid cake. The final moisture content depends on formulation, freezing rate, and the length of secondary drying.
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
Vaccine therapies are a type of specific active immunotherapy. Vaccine therapies deliver various agents that will lead to a specific immune response e.g. antibody development or CTL response. Tumor antigens have been a main target in specific active immunotherapy by way of vaccination. Tumor antigens are antigens produced by tumor cells and can be common among patients with the same cancer-type, or unique to a particular patient. Their specificity to malignant tumor cells makes tumor antigens ideal candidates for vaccination. Cancer vaccine C-Met#Active immunotherapy, Mantle cell lymphoma Immunotherapy,
Many RNAs are involved in modifying other RNAs. Introns are spliced out of pre-mRNA by spliceosomes, which contain several small nuclear RNAs (snRNA), or the introns can be ribozymes that are spliced by themselves. RNA can also be altered by having its nucleotides modified to nucleotides other than A, C, G and U. In eukaryotes, modifications of RNA nucleotides are in general directed by small nucleolar RNAs (snoRNA; 60–300 nt), found in the nucleolus and cajal bodies. snoRNAs associate with enzymes and guide them to a spot on an RNA by basepairing to that RNA. These enzymes then perform the nucleotide modification. rRNAs and tRNAs are extensively modified, but snRNAs and mRNAs can also be the target of base modification. RNA can also be methylated.
An antibody–drug conjugate consists of three components: Antibody - targets the cancer cell surface and may also elicit a therapeutic response. Payload - elicits the desired therapeutic response. Linker - attaches the payload to the antibody and should be stable in circulation only releasing the payload at the desired target. Multiple approaches to conjugation have been developed for attachment to the antibody and reviewed. DAR is the drug to antibody ratio and indicates the level of loading of the payload on the ADC.
Databases are essential for bioinformatics research and applications. Databases exist for many different information types, including DNA and protein sequences, molecular structures, phenotypes and biodiversity. Databases can contain both empirical data (obtained directly from experiments) and predicted data (obtained from analysis of existing data). They may be specific to a particular organism, pathway or molecule of interest. Alternatively, they can incorporate data compiled from multiple other databases. Databases can have different formats, access mechanisms, and be public or private. Some of the most commonly used databases are listed below: Used in biological sequence analysis: Genbank, UniProt Used in structure analysis: Protein Data Bank (PDB) Used in finding Protein Families and Motif Finding: InterPro, Pfam Used for Next Generation Sequencing: Sequence Read Archive Used in Network Analysis: Metabolic Pathway Databases (KEGG, BioCyc), Interaction Analysis Databases, Functional Networks Used in design of synthetic genetic circuits: GenoCAD
Sources: en.wikipedia.org
TMEM261 shows ubiquitous expression in humans and is detected in almost all tissue types. It shows tissue-enriched gene (TEG) expression when compared to housekeeping gene (HKG) expression. Its highest expression is seen in the heart (overall relative expression 94%) particularly in heart fibroblast cells, thymus (overall relative expression 90%), and thyroid (overall relative expression 93%) particularly in thyroid glandular cells. Staining intensity of cancer cells showed intermediate to high expression in breast, colorectal, ovarian, skin, urothelial, head and neck cells. Currently the function for TMEM261 is unknown. However, gene amplification and rearrangements of its locus have been associated with various cancers including colorectal cancer, breast cancer and lymphomas.
Many affected infants also have distinctive abnormalities of the head and facial (craniofacial) area. Many of the physical features associated with the disorder are congenital. In most cases, premature closure of fibrous joints (sagittal sutures) between certain bones (parietal bones) of the skull may restrict lateral growth of the skull, causing it to appear abnormally long and narrow that is disproportionate to the body size. In addition, the forehead may be abnormally prominent and the face may be triangular shaped with a hypo plastic mid face, pointed chin. Infants with this disorder may also have abnormally flat cheeks and cheekbones, large ears, prominent mouth with widely spread lips, and or underdeveloped upper jaw bones (maxillary hypoplasia). In addition, in some cases, the teeth may be abnormally crowded together, particularly toward the front of the mouth (anterior crowding) and as a result, the upper result, the upper jaw and lower teeth may not meet properly, they might be abnormally crowded together.
The operating principle of CCC equipment requires a column consisting of a tube coiled around a bobbin. The bobbin is rotated in a double-axis gyratory motion (a cardioid), which causes a variable g-force to act on the column during each rotation. This motion causes the column to see one partitioning step per revolution and components of the sample separate in the column due to their partitioning coefficient between the two immiscible liquid phases. "High-performance" countercurrent chromatography (HPCCC) works in much the same way as HSCCC. A seven-year research and development process produced HPCCC instruments that generated 240 g's, compared to the 80 g's of the HSCCC machines. This increase in g-force and larger bore of the column has enabled a ten-fold increase in throughput, due to improved mobile phase flow rates and a higher stationary phase retention. Countercurrent chromatography is a preparative liquid chromatography technique, however with the advent of the higher-g HPCCC instruments it is now possible to operate instruments with sample loadings as low as a few milligrams, whereas in the past hundreds of milligrams had been necessary. Major application areas for this technique include natural product purification and drug development.
Altria, like other tobacco companies, has invested in science and medical companies which develop and produce medical products for conditions caused or aggravated by smoking. As of 2024, Altria's three medical subsidiaries included the following: Cronos group (maker of recreational cannabis), Lexaria Bioscience (Developer of proprietary drug delivery technology, DehydraTECH, to improve active pharmaceutical ingredients entrance into the bloodstream) and Micreos (biotech company focused on discovering and developing recombinant proteins for chronic dermatology and oncology conditions). It has also designed and marketed electronic cigarettes. Altria launched the MarkTen and Green Smoke brands. Both of these were discontinued in December 2018. The company returned to this market through the acquisition of NJOY.
Topoisomerases are enzymes with both nuclease and ligase activity. These proteins change the amount of supercoiling in DNA. Some of these enzymes work by cutting the DNA helix and allowing one section to rotate, thereby reducing its level of supercoiling; the enzyme then seals the DNA break. Other types of these enzymes are capable of cutting one DNA helix and then passing a second strand of DNA through this break, before rejoining the helix. Topoisomerases are required for many processes involving DNA, such as DNA replication and transcription. Helicases are proteins that are a type of molecular motor. They use the chemical energy in nucleoside triphosphates, predominantly adenosine triphosphate (ATP), to break hydrogen bonds between bases and unwind the DNA double helix into single strands. These enzymes are essential for most processes where enzymes need to access the DNA bases.
Sources: en.wikipedia.org
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.