For the better part of five decades, stainless steel was the only credible architecture for commercial biopharmaceutical manufacturing. Fixed vessels, welded piping, clean-in-place and steam-in-place infrastructure, and facility timelines measured in years were simply the cost of entry into GMP production. The capital requirements were prohibitive for all but the most well-capitalized manufacturers, and the facilities that existed were built to run a single product at high volume for the lifetime of a commercial approval.
The economics have shifted fundamentally. For facilities targeting clinical and early commercial scale, manufacturing multiple products across a shared infrastructure, or responding to the compressed timelines of modern drug development, single-use architecture has become the default design choice. The question for most new biopharmaceutical facility projects is no longer whether to use single-use technology, but how to design a facility that maximizes what single-use makes possible.
The transition to single-use carries real and measurable operational advantages: lower capital commitment, faster commissioning, superior multi-product flexibility, and the elimination of cleaning validation as an ongoing operational burden. It also creates design requirements, supply chain obligations, and regulatory considerations specific to the disposable format. This guide covers the architecture, qualification approach, and operational design of a well-executed single-use biomanufacturing facility. For a broader view of bioprocessing scale-up and the manufacturing technologies shaping the industry, see the ultimate guide to bioprocessing scale-up and Pharma 4.0.
The facility design decision
The choice between single-use and stainless steel architecture is a financial and operational decision as much as a technical one. The table below maps the key decision factors across both platforms, using the dimensions most relevant to facility design, commissioning, and long-term operations.
Factor | Single-use | Stainless steel |
Facility capital cost | Lower; eliminates CIP/SIP systems, stainless vessel fabrication, and GMP piping runs | Higher upfront investment; appropriate where sustained high-volume production justifies the fixed asset |
Commissioning timeline | 12 to 18 months faster than equivalent stainless facility; no CIP/SIP installation or cleaning validation required | Longer timeline; CIP/SIP system installation, verification, and cleaning validation are significant commissioning activities |
Cleaning validation | Eliminated; disposable format removes inter-product carryover concern for product-contact surfaces | Required for each product-contact surface; must be repeated and revalidated for new products or cleaning agent changes |
Multi-product flexibility | High; changeover between product campaigns requires staging new single-use assemblies rather than cleaning and revalidating fixed equipment | Lower; cleaning validation is product-specific and limits the speed and economics of campaign changeover |
Per-run consumables cost | High; bags, tubing sets, filters, and sterile connectors are replaced with each production run | Low per run; hardware is reused with cleaning and sterilization between campaigns |
Supply chain risk | Higher; production continuity depends on qualified single-use component supply from a limited supplier base | Lower; relies on in-house utilities and reusable hardware with manageable spare parts exposure |
Best fit | Clinical-scale and early commercial production; multi-product facilities; programs requiring fast facility deployment | High-volume commercial manufacture of single products; facilities where annual consumables spend would exceed the stainless capital advantage |
Facility layout and design principles
Single-use biomanufacturing requires a different approach to facility layout than stainless steel design. The absence of CIP/SIP utility connections eliminates major constraints on room placement and piping routing, giving facility designers more flexibility in configuring production spaces. But single-use introduces its own spatial requirements, particularly around component staging and storage, that are frequently underestimated in facility planning.
Cleanroom classification and environmental control
The classified area requirements for a single-use biomanufacturing suite depend on whether the process uses open or closed systems at each step. Fully closed single-use assemblies, where all fluid paths are sealed and connections are made through sterile connectors rather than open-air manipulations, can be operated in ISO Class 8 (Grade D) environments for most operations. Steps involving open product contact, such as open-system sampling or aseptic connections not conducted inside an isolator or laminar flow hood, require ISO Class 7 (Grade C) conditions or better.
Designing for closed-system operation throughout the production suite maximizes the facility area that can be classified at Grade D rather than Grade C or B, reducing both the capital cost and the operational overhead of maintaining higher-classification environments. Facility designers should map each process step against its containment status before defining cleanroom classification requirements for each room.
Component staging and storage
Single-use facilities require substantially more staging and storage space adjacent to production areas than stainless steel facilities of equivalent production capacity. Bioreactor bags, tubing sets, filter capsules, sterile connectors, and other components must be stored under controlled conditions, transported to the point of use, inspected for integrity before use, and staged for installation. A 1,000-liter single-use production campaign may consume hundreds of individual single-use components. Allocating adequate staging space within or immediately adjacent to the production suite is a facility design decision with direct operational consequences.
Utility requirements
Single-use facilities still require utilities, but at a substantially different scale and configuration than stainless steel facilities. Purified water and water for injection remain necessary for buffer and media preparation, formulation, and cleaning of reusable equipment. Compressed gas delivery (nitrogen, air, carbon dioxide, oxygen) is required for bioreactor sparging and process control. Clean steam, if present at all, serves a more limited role than in stainless steel facilities. The elimination of CIP/SIP systems removes the large hot water, caustic, and steam utility loads that dominate stainless steel utility design.
From seed train to production bioreactor
The upstream design of a single-use facility defines the path from cell bank vial to production bioreactor, through a series of expansion steps that progressively increase culture volume while maintaining cell health and viability. Single-use bioreactors are available across the full range of volumes used in clinical and commercial manufacturing, from two-liter development systems to 2,000-liter production bioreactors, making fully single-use seed train design achievable for most applications.
Seed train design
A single-use seed train progresses the culture through increasing vessel volumes, with each stage timed to deliver cells at the target density and viability for inoculation of the next vessel. The table below illustrates a representative single-use seed train configuration for a 1,000-liter fed-batch production run.
Stage | Typical volume | Single-use system type | Duration |
Vial thaw and shake flask expansion | 50 mL to 3L | Shake flasks or small-scale wave bioreactor | 7 to 14 days from thaw to target density for inoculation |
N-4 / N-3 expansion | 3 to 15L | Single-use rocking bioreactor or small stirred-tank | 3 to 5 days per stage |
N-2 seed bioreactor | 50 to 100L | Single-use stirred-tank bioreactor | 3 to 5 days |
N-1 seed bioreactor | 100 to 250L | Single-use stirred-tank bioreactor; perfusion capable if N-1 perfusion strategy is used | 3 to 7 days (longer in perfusion mode) |
Production bioreactor | 500 to 2,000L | Single-use stirred-tank bioreactor | 10 to 14 days (fed-batch) or 30 to 90 days (perfusion) |
N-1 perfusion, running the final seed train stage in perfusion mode to achieve higher viable cell density at inoculation of the production bioreactor, is an increasingly common design choice for single-use facilities targeting process intensification. By increasing the inoculum VCD from 10 to 20 million cells per milliliter in standard fed-batch seed trains to 50 million cells per milliliter or higher in perfusion seed trains, N-1 perfusion can reduce production bioreactor run time or increase production bioreactor inoculation density without requiring the production bioreactor itself to operate in perfusion mode.
Production bioreactor selection
Production bioreactor selection for a single-use facility requires matching the vessel volume, geometric design, and control system capabilities to the process requirements. Key selection criteria include the oxygen transfer coefficient (kLa) achievable at the target agitation speed and gassing rate, the mixing time at maximum working volume, the range of temperature, pH, and dissolved oxygen control, and the control system architecture and its compatibility with process analytical technology (PAT) sensors.
Single-use bioreactors are available from all major bioprocessing equipment suppliers in standard volume configurations. Most commercial single-use production bioreactors at 200 liters and above use cylindrical stirred-tank designs with bottom-mounted or top-mounted impellers and submerged spargers, closely paralleling the geometry of stainless steel stirred-tank bioreactors. This geometric consistency supports scale-up translation using the same dimensionless criteria applied to stainless steel scale-up.
Downstream integration in a single-use facility
Downstream processing in a single-use biomanufacturing facility connects the harvest from the production bioreactor to the purified drug substance through a sequence of unit operations, most of which can now be implemented with single-use flow paths, filter assemblies, and holding vessels.
Harvest and primary clarification typically use depth filtration with single-use filter capsule assemblies, followed by sterile filtration into a single-use holding bag. Ultrafiltration and diafiltration (UF/DF) for concentration and buffer exchange use single-use tangential flow filtration cassette systems mounted in single-use flow path holders. Buffer and media preparation uses single-use mixing bags at volumes from 50 to 3,000 liters, eliminating the CIP requirements of stainless steel mixing tanks.
The downstream component that has been slowest to transition to fully single-use formats is large-scale chromatography. Protein A affinity capture, the standard first purification step for monoclonal antibodies, can be performed in single-use column formats at clinical scale, but large-scale single-use chromatography systems remain technically and economically limited compared to stainless steel column formats at commercial production volumes. For facilities planning for the long-term evolution of downstream processing technology, the related coverage of purification breakthroughs promising faster biologic development provides context on emerging approaches that may change this calculus.
Drug substance storage between downstream unit operations and at the end of the purification process uses single-use bags in 2-dimensional or 3-dimensional formats, held at 2 to 8 degrees Celsius for short-term hold or frozen in controlled-rate freezers for long-term storage at -80 degrees Celsius. Single-use bag integrity at freeze-thaw cycles is a qualification consideration that must be addressed during facility commissioning.
Commissioning and qualification timelines
The commissioning timeline advantage of single-use facilities is one of the most frequently cited arguments for the platform, and the advantage is real. Eliminating CIP/SIP systems removes the installation, qualification, and cleaning validation work that represents weeks to months of commissioning time in stainless steel facilities. A well-planned single-use facility can move from equipment delivery to first GMP production run in 12 to 18 months less than an equivalent stainless steel facility.
Qualification of single-use equipment follows the same IQ/OQ/PQ framework that applies to all GMP production equipment. The hardware platform, including the bioreactor controller, drive system, sensors, and process piping connections, requires full IQ/OQ/PQ qualification. Bag integrity testing for each individual production bag, confirming the absence of leaks before inoculation, is a per-run pre-use check rather than a qualification activity, but the procedure for conducting it must be established during qualification.
Leachables and extractables (L&E) testing is a commissioning requirement specific to single-use systems. All product-contact single-use components must be characterized for chemical entities that can leach from the plastic into the drug substance under process conditions. Major bioprocessing equipment suppliers publish extractables characterization packages for their single-use component portfolios, but sponsors are responsible for demonstrating that the extractables profile of each component is compatible with their specific drug substance under their specific process conditions. The regulatory expectations of FDA biologics guidances and EMA guidelines for biologics manufacturing both require that single-use system L&E data be included in regulatory submissions for biologic drug products.
The regulatory consequences of inadequate CMC documentation for biomanufacturing facilities, including single-use facilities, are well-established. Analysis of FDA complete response letters shows that manufacturing and quality deficiencies, including facility readiness gaps, are among the most common reasons for application rejection. For a detailed review of current regulatory expectations, see the related coverage of why gene and cell therapy programs are stalling at the FDA.
Supply chain design for single-use operations
The COVID-19 pandemic demonstrated at scale what single-use manufacturing experts had long understood: a facility whose production continuity depends on a single qualified supplier for critical single-use components is carrying supply chain risk that does not appear on its balance sheet until a shortage makes it visible. Bag availability constraints and sterile connector shortages disrupted biopharmaceutical manufacturing timelines across the industry in 2021 and 2022, affecting programs ranging from COVID-19 vaccine manufacturing to standard clinical-phase biologics production.
Designing supply chain resilience into a single-use facility requires decisions made before production begins. Component standardization, reducing the number of unique single-use assembly configurations to the minimum required for the production operations, simplifies inventory management and expands the range of suppliers capable of meeting specifications. Dual-source qualification, maintaining two qualified suppliers for each critical single-use component, provides an alternative supply path when primary supplier availability is constrained. Safety stock, maintaining a defined weeks-of-supply inventory for critical components at site, provides a buffer against short-term supply disruptions.
The BioPhorum industry consortium has published specific guidance on single-use supply chain risk management, including qualification frameworks for supplier assessment, component standardization strategies, and supply continuity planning approaches. Facilities designing their single-use supply chain should engage with current industry guidance rather than developing resilience strategies independently.
Supplier qualification for single-use components in GMP manufacturing requires assessing not only component performance but the supplier's quality management system, change notification practices, and manufacturing site audit history. A supplier that implements a change to film formulation, component design, or manufacturing process without adequate notification can create an uncontrolled change in the drug manufacturer's validated system, triggering requalification obligations and potential regulatory reporting requirements.
This article was produced under Drug Discovery News' AI Editorial Guidelines
