Sustainability is increasingly recognized as an essential characteristic of the modern systems, yet its definition often lacks precision and actionability. To address this gap, we conducted a systematic literature review on the definition and key domains of sustainability with a specific focus on the integration of biological elements within Cyber-Physical Systems & Spaces. Our research identified seven key domains where the interplay between sustainability on biological and cyber-physical perspective is crucial. Our findings led to the establishment of a conceptual model and the specification of a clear definition for biologically sustainable cyber-physical spaces. Through this conceptual model different environments were identified where cyber-physical systems interact harmoniously with biological components towards ensuring long-term sustainability. Future work will refine this model through mixed-methods research, by combining qualitative and quantitative approaches to deepen our understanding and applications of biological sustainability in these integrated systems.